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METTLER TOLEDO TItrators

Karl Fischer ApplicationsChemicals, Solvents, Petroleum Products, Plastics

Toluene

OIL

Glue

METTLER, Karl Fischer Applications 3

Contents 1. Introduction 4

2. Inorganic raw materials 5

3. Organic raw materials 9

4. Solvents 15

5. Petroleum products 21

6. Plastics and adhesives 27

7. Medicines (pharmaceuticals) 31

8. Dyes and agrochemicals 35

9. Detergents and surfactants 38

10. Silk, wool, cellulose, paper and wood 40

11. Building materials and minerals 42

12. Index of reagents and suppliers 44

13. KF reagent hazards and waste disposal tips 46

14. Sample Index 47

Karl Fischer Water Content Determinationin Chemicals, Solvents, Petroleum Products and Plastics

Fischer, K., Angew. Chem. 48, 394 (1935)

Mitchell Jr., J. and Smith, D.M., „Aquametry“ Part III, Second edition,John Wiley and Sons, Inc., New York, 1980

Riedel-de Haën, HYDRANAL® ManualFifth edition, 1988

Scholz, E., Karl Fischer Titration,Springer Verlag, Berlin, 1984

Wieland, G., Wasserbestimmung durch Karl-Fischer-Titration,GIT Verlag GmbH, Darmstadt, 1985

References

METTLER, Karl Fischer Applications4

1. Introduction

The quality and often the usability of many raw materials, intermediates and sub-stances necessary for the manufacturing of high-grade products frequently de-pend decisively on the water content. Securing and optimizing the product qualitythus necessitates regular control of the water content.

Karl Fischer titration, being efficient, rapid and accurate, is the most importantmethod for determining water contents. Thanks to its selectivity, the method fulfillstodays requirements. The traditional drying oven technique, in contrast, hasmany systematic errors, is inefficient and slow.

The method developed by Karl Fischer, in which water is titrated in the presenceof sulfur dioxide and an organic base [1], was improved significantly byE. Eberius, J.C. Verhoef and E. Scholz [2].

2 H20 + S02 + I2 —> H2S04 + 2 Hl [1]

H20 + I2 + S02 + CH30H + 3 RN —> [RNH]S04CH3 + 2 [RNH]I [2]

In an initial reaction, sulfur dioxide, methanol and the base have recently beenshown to react to form methyl sulfite [RNH]SO3CH3.

The pyridine used initially by Karl Fischer has been replaced by more suitableamines. Several companies supply pyridine-free Karl Fischer reagents with aconstant titer.

Microprocessor controlled METTLER DL18 and DL35 Karl Fischer titrators as wellas METTLER DL37 KF Coulometer allow water contents to be determined rapidly,easily and reproducibly. The DL35 and DL18 are recommended for water con-tents ranging from ppm to 100%, whereas the DL37 is useful for trace moisturecontent determinations.

Karl Fischer titration allows the quantification of freely available water which hasbeen brought into solution prior to the titration using an appropriate method.

Gases and liquids are generally easily dissolved in methanol, the usual solventfor Karl Fischer titration.

Solids, however, may contain water as water of crystallization, occluded water oras adherent moisture. For this reason, sample preparation is most important forthe analysis. A total water content determination requires that the sample be com-pletely dissolved. Should this not be possible in methanol, it may be necessary toadd decanol, chloroform, formamide or other solvents. In certain instances titra-tion at elevated temperatures, at the boiling point, or after external extraction maybe helpful.

For thermally stable products, such as polymers, evaporation of the moisture in adrying oven (METTLER DO302 or DO337) and transferring the vapor into thetitration cell by a dry purge gas is recommended.

The differential availability of the water may be used to selectively quantify onlythe adherent moisture (for plastics, for instance). It is, however, necessary to pre-vent the rediffusion of more water.

Undesirable side reactions of the KF reagents, such as esterification or bisulfiteaddition, may be prevented by the proper selection of reactant composition andmeasurement conditions.


2. Inorganic raw materials

References: ISO 3699-1976 Anhydrous Hydrogen Fluoride for Industrial Use – Determi-nation of Water Content – Karl Fischer Method

ISO/DIS 7105 Liquified Anhydrous Ammonia for Industrial Use – Determina-tion of Water Content – Karl Fischer Method

Bryant, W.M.D. and Mitchell, J., Analytical Procedures Employing KarlFischer Reagent (Determination of Water of Hydration in Salts in InorganicOxides and Related Components), J. Am. Chem. Soc. 63, 2924-2930(1941)

General comments SaltsSalts can contain water in the following ways: water of crystallization, in-cluded water and adherent moisture.In order to quantify water of crystallization and included water, the samplemust be dissolved completely. Methanol is usually a suitable solvent.Some substances may require the addition of formamide, or titration at ele-vated temperatures. For substances that dissolve slowly, finely crushing thesample may be helpful.When determining only the adherent moisture, dissolution of the substanceand diffusion of other water into the titration must be prevented. For thisreason, a high proportion of chloroform is used in the solvent.

Acids and basesThese must be neutralized prior to the titration. Imidazole or pyridine areused for acids, benzoic acid or salicylic acid for bases.Strong acids also tend to undergo esterification, whereby water is formed(for example highly concentrated acids such as gaseous HCl or H2SO496%).

The following inorganic compounds react with Karl Fischer reagents in aside reaction which leads to an incorrect water content:peroxides, oxides, hydroxides, carbonates, hydrogen carbonates, disulfites,nitrites, sulfites, thiosulfates, hydrazine and derivatives, iron(III) salts,copper(I) salts, tin(II) salts, silanols, arsenites, arsenates, selenites, tellu-rites and boron compounds.For these compounds a direct KF titration is not suitable. The moisture fromthermally stable compounds should be evaporated in a drying oven andthe moisture transferred into the titration cell with a dry purge gas. Externalextraction may also be used; however, the sample must be insoluble in theextraction solvent.


Applications: Inorganic raw materials

A) Volumetric determination using DL35

Sample Weight Result RSD Titrant Methodg n % % Solvent

CaCl2 • 2H2O 0.1 6 26.4 0.46 Composite 5 Sample input: weighing boat30 mL methanol Stir time: 50 s

Phosphoric acid 0.15 6 13.7 0.5 Titrant 5 Sample input: syringe with needle30 mL solvent Stir time: none20 mL buffer

Sulfuric acid 0.1 6 4.63 1.4 Titrant 5 Sample input: syringe with needleapprox. 96% 30 mL solvent Stir time: none

20 mL buffer

Sodium 1.7 6 0.443 3.2 Composite 2 Evaporate moisture with drying ovencarbonate 40 mL methanol DO302: 250 °C, 200 mL N2/min

Stir time: 700 s

Calcium oxide 1.5 5 0.227 10.9 Composite 2 Evaporate moisture with drying oven40 mL methanol DO302: 250 °C, 200 mL N2/min

Stir time: 600 s

Aluminum oxide 1.3 6 0.148 2.2 Titrant 2NH Sample input: weighing boat30 mL solvent Stir time: 300 s

Reagents:Titrant 2NH: two component reagent HYDRANAL® Titrant 2NH, Riedel No. 34811 (titrant)Titrant 5: two component reagent HYDRANAL® Titrant 5, Riedel No. 34801 (titrant)Solvent: two component reagent HYDRANAL® Solvent, Riedel No. 34800 (solvent)Composite 2: one component reagent HYDRANAL® Composite 2, Riedel No. 34806 (titrant)Composite 5: one component reagent HYDRANAL® Composite 5, Riedel No. 34805 (titrant)Buffer: buffer 5mmol acid/mL HYDRANAL® Buffer, Riedel No. 34804

B) Coulometric determination using DL37

Sample Weight Result RSD Reagents Methodg n % %

Magnesium 0.07 5 4.6 2.4 100 mL Coulomat A Evaporate moisture with drying ovenoxide 5 mL Coulomat C DO337: 250 °C, 200 mL air/min

Titration time: 400 s

Sodium chloride 1.0 5 0.0360 4.2 100 mL Coulomat A Evaporate moisture with drying oven5 mL Coulomat C DO337: 300 °C, 200 mL air/min


Lithium chloride 1.0 5 0.7088 3.4 100 mL Coulomat A Evaporate moisture with drying oven5 mL Coulomat C DO337: 250 °C, 200 mL air/min


Aluminum 3.0 6 0.0212 3.4 100 mL Coulomat A Evaporate moisture with drying ovenpowder 5 mL Coulomat C DO337: 280 °C, 200 mL air/min


Titration parameters for titrations with drying oven DO337:Adjustment: control gain: 5; switch-off criterium: fixed titration timeautomatic drift determination, manual titration start

Reagents:Coulomat A: anode reagent HYDRANAL® Coulomat A, Riedel No. 34807Coulomat C: cathode reagent HYDRANAL® Coulomat C, Riedel No. 34808


Comments concerning applications using DL35


Magnesium oxide

Sodium chloride,lithium chloride,

aluminum powder

Calcium chloride

Phosphoric acid

Sodium carbonate

Sulfuric acidapprox. 96%

Calcium oxide

Aluminum oxide

The sample is slightly hygroscopic. All 6 samples could be titrated in theindicated amount of solvent.

The direct titration is unproblematic. The sample must be neutralized with abase (such as imidazole), otherwise the endpoint will be sluggish.

The sample is hygroscopic. The plastic syringe must be discarded after3 samples, as the acid will attack it.Neutralization of the sample with a base (i.e., imidazole) is necessary.

Carbonate reduces iodine to give iodide, which results in an erroneouslyhigh water content.Na2CO3 + I2 + SO2 + CH3OH –> 2NaI + CO2 + HSO4CH3For this reason the drying oven is used.An external extraction with methanol results in values that are too high,since sodium carbonate is slightly soluble in methanol.

The KF solutions are always weakly acidic, thus they may react with oxidesin a reaction that produces water. CaO + 2 HI –> CaI2 + H2OThis is why use of the drying oven is recommended.An external extraction with methanol results in elevated values, as traces ofcalcium oxide will dissolve in methanol.

Aluminum oxide is not basic enough to react with the KF solution. Directtitration is possible. The sample is highly hygroscopic, thus contact with theambient is to be held at a minimum.The sample releases water slowly, therefore it is necessary to stir for5 minutes.

Many inorganic salts have low water contents and are thermally stable.For this reason a coulometric determination using a drying oven is an idealmethod.

The high water content necessitates a small sample. This in turn requiresthat the sample be homogeneous in order to get reproducible results.

The coulometric determination using the drying oven is unproblematic.


Karl Fischer TitrationWater Content Determination of Inorganic Solids

A. Aichert, Application Laboratory, Nov. 1990

Method:

Sample: 3 g Aluminum powder

Preparation:Heat sample in a crucible, evaporatethe moisture and transfer the vapor intothe titration cell by a dry purge gas.Oven temperature: 280 °CPurge gas: 200 mL air/minute

Sample Input:Fill sample from weighing boat throughconnection piece into the crucible.

Cathode Solution:5 mL Catholyte(HYDRANAL® Coulomat C No. 34808)

Anode Solution:100 mL Anolyte(HYDRANAL® Coulomat A No. 34807)

Comments:Titration time: 15 minutesThe time required for evaporation of thewater is preferably entered as a fixedtitration time (parameter L.Time).See the operating instructions of thedrying oven for instructions regardingits use.

Application:Chemical industry

Instruments:METTLER DL37 KF CoulometerDrying oven METTLER DO337

Result und Statistics:


3. Organic Raw Materials

General comments Hydrocarbons, halogenated hydrocarbons, alcohols, esters and etherThe water content determination of these substances is unproblematic.Adding propanol or chloroform increases the solubility of long chainedcompounds. Double bonds rarely cause problems.These compounds generally contain little water, thus coulometry is particu-larly recommended. Halogenated hydrocarbons may contain activechlorine from the production process. The active chlorine oxidizes iodide toiodine (resulting in an erroneously low water content).

PhenolsFor most phenols the water content determination is unproblematic. Insome cases salicylic acid may need to be added as a buffer. Some phenolshave been shown to have a high post-consumption (for example, amino-phenol).

Aldehydes and ketonesThese compounds react with methanol to produce acetals and ketals re-spectively. Water is produced in the reactions. These side reactions may besuppressed by using methanol-free titrants and solvents. Special reagentsfor the water content determination of aldehydes and ketones are available.Bisulfite addition is a further side reaction which aldehydes will undergo.This reaction consumes water and starts as soon as the sample is added tothe solvent containing sulfur dioxide. The titration must thus be started im-mediately to circumvent the bisufite addition.

Organic acidsStrongly acidic organic acids should be neutralized to keep the pH value inthe proper range for a KF titration.

Nitrogen compoundsStrongly basic amines are neutralized with benzoic acid. The solubility ofhigher amines needs to be improved by adding chloroform.A few amines titrated with methanol as the solvent show an unstable end-point (such as aniline, toluidine, aminophenol), probably due to a sidereaction. This can be eliminated by using a methanol-free solvent.The water content determination of hydroxylamine, hydrazine and hydra-zine salts is difficult. Their oxidation by iodine results in erroneously highwater contents.

Sulfur compoundsThe determination of these compounds is unproblematic. Exceptions aremercaptans and thiols. These are oxidized by iodine, resulting in errone-ously high water contents.

References Scholz, E., Wasserbestimmung in Carbonsäuren,Fresenius Z. Anal. Chem. 312, 423-426 (1982)

Scholz, E., Titration of Aldehydes and KetonesAnal. Chem. 57, 2965-2971 (1985)

Scholz, E., Wasserbestimmung in PhenolenFresenius Z. Anal. Chem. 330, 8, 694-697 (1988)


Applications: Organic raw materials



4-Chlorotoluene 2.5 8 0.0089 2.3 Composite 2 Input: syringe with needle30 mL methanol Stir time: none

Benzyl alcohol 2.5 7 0.137 0.57 Composite 2 Input: syringe with needle30 mL methanol Stir time: none

2-Nitrophenol 2.0 6 0.0549 1.9 Titrant 2NH Crush sample in mortar30 mL solvent Input: weighing boat10 mL buffer Stir time: 30 s

Acetophenone 2.0 8 0.524 0.41 Composite 5K Input: syringe with needle30 mL Stir time: noneWorking medium K

Benzaldehyde 1.0 8 0.168 0.32 Composite 5K Input: syringe with needle30 mL Stir time: noneWorking medium K Start titration immediately

Salicylic acid 1.0 6 0.0140 0.8 Composite 2 External dissolution in methanol:30 mL methanol dissolve 30 g in 60 mL MeOH,

Input: 3 ml aliquot with syringe

Oxalic acid 0.06 6 27.9 0.43 Titrant 5 Input: weighing boat20 mL solvent Stir time: 300 s20 mL buffer

Methyl benzoate 3.0 6 0.0083 2.8 Composite 1 Input: syringe with needle30 mL methanol Stir time: none

Urea 2.0 6 0.123 4.4 Composite 2 Input: weighing boat30 mL methanol Stir time: none

n-Butylamine 0.5 7 1.12 0.4 Titrant 2NH Input: syringe with needle30 mL solvent Stir time: none4 g benzoic acid

Aniline 2.5 6 0.0819 2.7 Composite 5K Input: syringe with needle30 mL Stir time: noneWorking medium K5 g salicylic acid

Reagents:Titrant 2NH: two component reagent HYDRANAL® Titrant 2NH, Riedel No. 34811 (titrant)Solvent: two component reagent HYDRANAL® Solvent, Riedel No. 34800 (solvent)Composite 1: one component reagent HYDRANAL® Composite 1, Riedel No. 34827 (titrant)Composite 2: one component reagent HYDRANAL® Composite 2, Riedel No. 34806 (titrant)Composite 5: one component reagent HYDRANAL® Composite 5, Riedel No. 34805 (titrant)Composite 5K: one component reagent HYDRANAL® Composite 5K, Riedel No. 34816

(Titrant for aldehydes and ketones)Working medium K: one component reagent HYDRANAL® Working Medium K, Riedel No. 34817

(Solvent for aldehydes and ketones)Buffer: buffer 5mmol acid/mL HYDRANAL® Buffer, Riedel No. 34804


4-Chlorotoluene,benzyl alcohol

Comments concerning applications with DL35

2-Nitrophenol

Acetophenone

The direct titration is unproblematic. A titrant with a low concentration(2 mg H2O/mL) is used due to the low water content.

The sample crushed in the mortar dissolves easily in the solvent. Without abuffer an elevated post-consumption is observed.

Ketones react with methanol to give ketals and water. To prevent this, amethanol-free titrant and solvent are used.The solvent should be changed after 4 samples.

Aldehydes react with methanol to form an acetal and water. To prevent this,a methanol-free titrant and solvent should be used. A further side reaction isbisulfite addition, which consumes water. For this reason the titration isstarted immediately after injecting the sample. The weight is entered on thetitrator after the titration.The solvent must be replaced after each sample. When performing severaltitrations in the same solvent a decrease in the determined water content isobserved.

Finely pulverized salicylic acid may become electrostatically charged,causing problems during transfer of the sample into the titration cell. Thetitration cell remains open for different lengths of time. This may lead toconsiderable scatter of the results when titrating small quantities of water.For this reason, external dissolution in methanol is used. This solution mustbe analyzed immediately, as an increasing amount of water (i.e., 250 ppmafter 24 h) is determined after the solution has been standing for some time(over 3 hours). The cause is a slow esterification of the acid.

The solvent is to be replaced after 2 samples as its buffering capacity willbe exhausted.

The direct titration is straightforward. Due to the low water content, a titrantwith the concentration of 1 mg H2O/ml was used.

As urea is slightly soluble in methanol, the solvent must be replaced aftereach sample.

The endpoint is sluggish in spite of the neutralization with benzoic acid.The results are too high and poorly reproducible. Decreasing the switch-offdelay to 7 seconds allows reliable and reproducible results to be obtained.

No stable endpoint could be achieved using methanol as the solvent. Usinga methanol-free solvent eliminates this problem. Neutralizing the anilinewith salicylic acid is necessary, otherwise the endpoint will be sluggish.

Benzaldehyde

Salicylic acid

Oxalic acid

Methyl benzoate

Urea

n-Butylamine

Aniline


Applications: Organic raw materials


Sample Weight Result RSD Reagents Methodg n ppm %

Naphtaline 0.1 6 35.0 10.2 100 mL Coulomat A external dissolution in MeOH:5 mL Coulomat C dissolve 0.4 g in 25 mL MeOH

Input: 5 mL aliquot with syringeStir/Titration time: 0/40 s

4-Chlorotoluene 0.8 6 30.7 1.7 100 mL Coulomat A Input: syringe with needledried (1) 5 mL Coulomat C Stir/Titration time: 0/40 s

Benzylalcohol 0.4 6 1273 0.16 100 mL Coulomat A Input: syringe with needledried (1) 5 mL Coulomat C Stir/Titration time: 0/80 s

Phenol 1.0 6 173.7 1.8 100 mL Coulomat A external dissolution in MeOH:5 mL Coulomat C dissolve 17 g in 60 mL MeOH


Acetophenone 0.3 6 2830 0.46 100 mL Coulomat AK Input: syringe with needledried (1) 5 mL Coulomat CK Stir/Titration time: 0/120 s

Benzaldehyde 0.4 6 242.6 0.9 100 mL Coulomat AK Input: syringe with needledried (1) 5 mL Coulomat CK Stir/Titration time: 0/90 s

Salicylic acid 0.4 6 115.8 2.9 100 mL Coulomat A external dissolution in MeOH:5 mL Coulomat C dissolve 30 g in 60 mL MeOH

(titrate immediately)Input: 3 mL aliquot with syringeStir/Titration time: 0/50 s

Methyl- 0.9 6 49.1 2.0 100 mL Coulomat A Input: syringe with needlebenzoate 5 mL Coulomat C Stir/Titration time: 0/120 sdried (1)

Benzamide 0.3 6 117.5 3.6 100 mL Coulomat A External dissolution in MeOH:5 mL Coulomat C dissolve 16 g in 50 mL MeOH


n-Butylamine 0.2 6 1.14% 0.8 100 mL Coulomat A Input: syringe with needle20 g benzoic acid Stir/Titration time: 0/200 s5 mL Coulomat C

Aniline 0.1 1 No result 100 mL Coulomat AK Input: syringe with needle20 g benzoic acid5 mL Coulomat CK

Standard titration parameters for all titrations:Adjustment: control gain: 5 switch-off criterium: End level 0.1 µg/s (0.1 µg H2O/s above drift value)automatic drift determination, automatic titration start

(1) Dried over molecular sieve 3Å

Reagents:Coulomat A: anode reagent HYDRANAL® Coulomat A, Riedel No. 34807Coulomat C: cathode reagent HYDRANAL® Coulomat C, Riedel No. 34808Coulomat AK: anode reagent HYDRANAL® Coulomat AK, Riedel No.34820Coulomat CK: cathode reagent HYDRANAL® Coulomat CK, Riedel No.34821


Comments concerning the applications with DL37

Naphtaline A small weigh-in is needed, as napthaline is poorly soluble in methanol.The coulometric determination with external dissolution is unproblematic.

The coulometric determination is straightforward.

Phenol is first dissolved externally in methanol.

Ketones react with methanol to form a ketal and water. To prevent this, amethanol-free anolyte and catholyte are used.With these reagents the titration of acetophenone is straightforward andgives reproducible results.

Aldehydes react with methanol to give an acetal and water. To circumventthis, methanol-free anolyte and catholyte solutions are used. A further sidereaction is bisulfite addition, a process in which water is consumed.The titration is started using AUTOSTART immediately after sample addition.The sample weight is entered on the DL37 during or after the titration.

Salicylic acid and benzamide are dissolved in methanol and the externalsolution is then titrated. The salicylic acid solution must be analyzed imme-diately, since the water content increases upon standing for over 3 hours(for example, 250 ppm after 24 hours). The slow esterification of the acidis the cause.

This is titrated coulometrically by adding benzoic acid. The determinedvalues tend to increase within the series, resulting in a decreasing repro-ducibility.

Aniline will not give a stable endpoint using methanol as the solvent. Evenafter using methanol-free reagents and after neutralizing the aniline withsalicylic acid, a coulometric titration proved to be impossible (no endpoint).

Phenol

Acetophenone

Benzaldehyde

Salicylic acid andbenzamide

n-Butylamine

Aniline

4-Chlorotoluene,benzyl alcohol,

methyl benzoate



Karl Fischer TitratrionWater Content Determination of Organic Solids

Sample: 0.3 g Phenol

Method:Preparation:17 g phenol are dissolved in 47 gmethanol in a bottle sealed with a sep-tum. 1 mL aliquots of the solution aretaken with a syringe for the titration.Determine the water content of the me-thanol and enter this as Parameter A.

Sample Input:Syringe with needle(such as ME-71482)

Catholyte:5 mL Catholyte(HYDRANAL® Coulomat C, No. 34808)

Anolyte:100 mL Anolyte(HYDRANAL® Coulomat A, No. 34807)

Comments:Titration time: 70 secondsFor the coulometric water content de-termination of solids, an external ex-traction or external dissolution must beused. Adding solids directly into thetitration cell by opening the stopperresults in erroneously high water con-tents (variance greater than 50%).The DL37 has special calculation for-mulas for external extraction and exter-nal dissolution. The parameters are:A water content of the solvent

(ppm)B total solvent amount (g)WtO amount of sample dissolved in B

solventNet Aliquot amount (g)

Application:Chemistry, plastics, pharmaceuticals

Instruments:METTLER DL37 KF Coulometer

Result and Statistics:


References Scholz, E., Titration of Aldehydes and KetonesAnal. Chem. 57, 2965-2971 (1985)

ISSN 0192-2971, ASTM Standard, D-1364-87, 1987Test method for water in volatile solvents (Karl Fischer Titration)

4. Solvents

Toluene

General comments Hydrocarbons, halogenated hydrocarbons, alcohols, esters and etherThe water content determination of these substances is unproblematic.Adding propanol or chloroform increases the solubility of long chainedcompounds. Double bonds rarely cause problems.These compounds generally contain little water, thus coulometry is particu-larly recommended. Halogenated hydrocarbons may contain activechlorine from the production process. The active chlorine oxidizes iodide toiodine (resulting in an erroneously low water content).

PhenolsFor most phenols the water content determination is unproblematic. Insome cases salicylic acid may need to be added as a buffer. Some phenolshave been shown to have a high post-consumption (for example, amino-phenol).

Aldehydes and ketonesThese compounds react with methanol and produce acetals and ketals,respectively. Water is produced in the reactions. These side reactions maybe suppressed by using methanol-free titrants and solvents. Special rea-gents for the water content determination of aldehydes and ketones areavailable.Bisulfite addition is a further side reaction which aldehydes will undergo.This reaction consumes water and starts as soon as the sample is added tothe solvent containing sulfur dioxide. The titration must thus be started im-mediately to prevent the bisulfite addition.

Organic acidsStrongly acidic organic acids should be neutralized to keep the pH value inthe proper range for a KF titration.

Nitrogen compoundsNitrogen-containing solvents such as amides (i.e., dimethylformamide),nitro compounds (such as nitrobenzene), and nitriles (acetonitrile) are un-problematic.


Applications: Solvents



Toluene 3.0 6 0.0144 0.37 Composite 2 Input: syringe with needle30 mL methanol Stir time: none

Cyclohexene 2.5 7 0.0080 1.5 Composite 1 Input: syringe with needle30 mL methanol Stir time: none

iso-Amyl alcohol 2.0 6 0.141 0.25 Composite 2 Input: syringe with needle30 mL methanol Stir time: none

Ethylen glycol 2.0 6 0.651 0.24 Composite 2 Input: syringe with needle30 mL methanol Stir time: none

Methylene 3.0 6 0.0115 1.2 Composite 2 Input: syringe with needlechloride 30 mLmethanol Stir time: 60 s

Diethylether 1.5 6 0.0553 0.40 Composite 2 Input: syringe with needle30 mL methanol Stir time: none

Acetone 3.0 7 0.0128 0.48 Composite 5K Input: syringe with needle30 mL Stir time: noneWorking medium K

Isobutylmethyl- 1.5 6 0.145 0.39 Composite 5K Input: syringe with needleketone (IBMK) 30 mL Stir time: none

Working medium K

Formaldehyde 0.04 6 52.0 0.58 Titrant 5 Input: syringe with needle30 mL solvent Stir time: none20 mL buffer

Acetaldehyde 1.3 6 0.0337 4.2 Composite 5K Cool sample to 0 °C30 mL Input: syringe with needleWorking medium K Titrate immediately

Acetic acid 1.0 6 0.263 0.24 Titrant 2NH Input: syringe with needle30 mL solvent Stir time: none20 mL buffer

Dimethylforma- 1.5 7 0.0867 0.36 Titrant 2NH Input: syringe with needlemide (DMF) 20 mL solvent Stir time: none

20 mL buffer

Acetonitrile 3.0 7 0.0128 2.3 Composite 2 Input: syringe with needle30 mL methanol Stir time: none

Reagents:Titrant 2NH: two component reagent HYDRANAL® Titrant 2NH, Riedel No. 34811 (titrant)Solvent: two component reagent HYDRANAL® Solvent, Riedel No. 34800 (solvent)Composite 1: one component reagent HYDRANAL® Composite 1, Riedel No. 34827 (titrant)Composite 2: one component reagent HYDRANAL® Composite 2, Riedel No. 34806 (titrant)Composite 5: one component reagent HYDRANAL® Composite 5, Riedel No. 34805 (titrant)Composite 5K: one component reagent HYDRANAL® Composite 5K, Riedel No. 34816

(Titrant for aldehydes and ketones)Working medium K: one component reagent HYDRANAL® Working Medium K, Riedel No. 34817

(Solvent for aldehydes and ketones)Buffer: buffer 5 mmol acid/mL HYDRANAL® Buffer, Riedel No. 34804



The direct titration is straightforward. Since the water content of these com-pounds is low, a titrant with 2 mg H2O/mL is used.

A diluted titrant with a concentration of 1 mg H2O/mL is used to determinethe low water content of 80 ppm.To achieve a good reproducibility of 1.5% RSD, the following points areimportant:– Condition syringe well with the sample– Replace the solvent after each 3 samples(The result using titrant 2 mg H2O/mL: RSD = 2.7% for 6 samples, sampleweight 2 g)

Ketones react with methanol generating a ketal and water. Methanol-freesolvents and titrants must be used to prevent this.

Formaldehyde will not react with methanol to form an acetal, thus metha-nol-containing reagents may be used.The total water content cannot be determined by titrating at room tempera-ture, as a part of the water is bound as paraformaldehyde.Even at 50 °C, not all the water will be released (theoretical water content= 55.8%).

Acetaldehyde boils at 15 °C. To simplify sample input with a syringe, coolthe sample to approx. 0 °C.Acetal formation can be detected by the high post-comsumption, eventhough methanol-free reagents were used. Reducing the switch-off delay to7 seconds reduces the titration time and increases the reproducibility.Additionally, the sample size was selected to be as small as possible andwas kept constant. The solvent was also renewed after each sample. Bisul-fite addition occurs as a further side reaction. Water is consumed in thisreaction. To circumvent this problem, the titration is started immediatelyafter sample addition. The sample weight is entered on the titrator after thetitration.

Acetic acid has a slight tendency to esterify. Thus it is necessary to add abuffer.

The Karl Fischer titration of DMF is straightforward. This is expected to betrue for amides of other carboxylic acids as well.

The water content determination of acetonitrile is unproblematic.

Toluene, isoamyl-alcohol, ethyleneglycol,

methylene chloride,diethylether

Formaldehyde

Acetaldehyde

Acetic acid

Dimethylformamide

Acetonitrile

Cyclohexene

Acetone,Isobutylmethylketone


Applications: Solvents



Toluene 3.0 6 4.8 9.8 100 mL Coulomat A Input: syringe with needledried (1) 5 mL Coulomat C Stir/Titration time: 0/60 s

n-Hexane 1.0 6 10.5 7.2 100 mL Coulomat A Input: syringe with needleSample 1 dried (1) 5 mL Coulomat C Stir/Titration time: 0/36 s

n-Hexane 2.0 8 4.6 9.1 100 mL Anolyte Input: syringe with needleSample 2 dried (1) 5 mL Catholyte Stir/Titration time: 0/50 s

Cyclohexene 0.8 6 78.8 1.2 100 mL Coulomat A Input: syringe with needle5 mL Coulomat C Stir/Titration time: 0/70 s

Isopropyl 0.2 6 787.6 0.31 100 mL Coulomat A Input: syringe with needlealcohol 5 mL Coulomat C Stir/Titration time: 0/40 s

Ethylene 0.4 6 6541 0.56 100 mL Coulomat A Input: syringe with needleglycol 5 mL Coulomat C Stir/Titration time: 0/440 s

Ethylene chloride 0.6 6 38.2 3.2 100 mL Coulomat A Input: syringe with needledried (1) 5 mL Coulomat C Stir/Titration time: 0/80 s

Diethylether 0.5 6 40.0 4.0 100 mL Coulomat A Input: syringe with needledried (1) 5 mL Coulomat C Stir/Titration time: 0/50 s

Acetaldehyde 0.5 1 no result 100 mL Coulomat AK Cool sample to 0 °C5 mL Coulomat CK Input: syringe with needle

Acetone 0.7 6 118.0 0.68 100 mL Coulomat AK Input: syringe with needledried (1) 5 mL Coulomat CK Stir/Titration time: 0/100 s

Isobutyl- 0.4 6 717.0 0.18 100 mL Coulomat AK Input: syringe with needlemethylketone 5 mL Coulomat CK Stir/Titration time: 0/100 sdried (1)

Ethyl acetate 0.5 6 34.9 1.2 100 mL Coulomat A Input: syringe with needledried (1) 5 mL Coulomat C Stir/Titration time: 0/48 s

Dimethyl- 0.4 6 347.3 1.0 100 mL Coulomat A Input: syringe with needleformamide 5 mL Coulomat C Stir/Titration time: 0/60 sdried (1)

Standard titration parameters for all titrations:Adjustment: control gain: 5; switch-off criterium: End level 0.1: µg/s (0.1 µg H2O/s above drift value)automatic drift determination, automatic titration startFor toluene and n-hexane sample II:control gain: 3; switch-off criterium: End level 0.05: µg/s (0.05 µg H2O/s above drift value)

(1) Dried over molecular sieve 3 Å

Reagents:Coulomat A: anode reagent HYDRANAL® Coulomat A, Riedel No. 34807Coulomat C: cathode reagent HYDRANAL® Coulomat C, Riedel No. 34808Coulomat AK: anode reagent HYDRANAL® Coulomat AK, Riedel No. 34820Coulomat CK: cathode reagent HYDRANAL® Coulomat CK, Riedel No. 34821

Anolyte: anode reagent KF reagent for coulometric water content determination, MERCK No. 9255Catholyte: cathode reagent KF reagent for coulometric water content determination, MERCK No. 9255



Dryed solvents contain little water, sometimes only traces, thus KF coulo-metry is particularly recommended.

Toluene and n-hexane sample II were dried for 24 hours over 3 Å molecu-lar sieve.n-Hexane sample I was dried for 1 hour over 3 Å molecular sieve.These examples show that the METTLER DL37 KF coulometer allows repro-ducible results to be obtained even for trace amounts of water(i.e., 4.6 ppm ± 0.4 ppm).

The coulometric titration of these samples is straightforward.

Ketones react with methanol, generating ketals and water. To prevent this,a methanol-free anolyte and catholyte are used.

The boiling point of acetaldehyde is 15 °C. To simplify sample input with asyringe, the sample should be cooled to approximately 0 °C.In spite of the use of methanol-free reagents, acetal formation proceeds at arate that makes the coulometric water content determination impossible.

This compound is easily analyzed by KF coulometry. This is to be expectedfor other acid amides as well.

These examples show that the METTLER DL37 KF Coulometer providesreliable and exact values even in the trace water range, such as4.6 ppm ± 0.4 ppm.

Toluene and n-hexane

Cyclohexene, isopropa-nol, ethylene glycol,

ethylene chloride,diethylether,ethyl acetate

Acetone,isobutylmethylketone

Acetaldehyde

Dimethylformamide


Karl Fischer TitrationWater Content Determination of Solvents


Sample: 2 g n-hexane dried over molecular sieve 3Å

Preparation:Keep sample in a septum flask.

Sample Input:Syringe with needle (i.e., ME-71482)

Catholyte:5 mL Catholyte(KF reagent for coulometric waterdetermination, MERCK No. 9255)

Anolyte:100 mL Anolyte(KF reagent for coulometric waterdetermination, MERCK No. 9255)

Comments:Titration time: 50 secondsSamples with low moisture contents inthe ppm range should be stored inseptum flasks. These samples are ge-nerally hygroscopic, thus the originalwater content is considerably alteredand falsified by any contact with theambient (open flask, sample transfer,etc.).When removing the sample, the pres-sure loss should be compensated withdried air only.

Application:Chemistry, petroleum products,polymers, pharmaceuticals

Instruments:METTLER DL37 KF Coulometer

Method:

Results und Statistics:


5. Petroleum Products

References ISO/DIS 5381, Flüssige Petroleum Produkte – Wasserbestimmung nachKarl Fischer

DIN 51777 Teil I, Test von Mineralöl, Kohlenwasserstoffen und Lösungs-mittlen, Wasserbestimmung nach Karl Fischer. Direkte Methode.

ASTM-Standard, D-4377-88, 1988Test method for water in crude oils (Karl Fischer Titration)

OIL

Mineral oilsMineral oils can be completely dissolved only in the presence of chloro-form. The chloroform may be replaced by 1-decanol or the special solventfor oils and fats when analyzing light mineral oil products (i.e, benzene,kerosine, diesel oil or heating oil). Crude oils, some of which contain tarrycomponents, are best dissolved in a methanol/chloroform/toluene mixture.Motor oils contain additives that may interfere with the KF titration (such asketones, keto acids, zinc-dialkyl-dithiophosphates, calcium or magnesiumsulfonates). In this case the drying oven can be used. The temperatureshould be adjusted to 120–140 °C, as the additives may decompose.Mineral oils have low moisture contents (frequently less than 100 ppm).For these samples, KF coulometry is particularly suitable. Crude oils con-tain insoluble impurities that may clog the diaphragm. The drying oven isbest used for these samples.

Silicon oilsThe solubility of silicon oils must be improved by the addition of chloroformor 1-decanol.

FatsSome fats are not rendered soluble even after adding chloroform. In thesecases, external extraction in pure chloroform or use of the drying oven(temperature 120–140 °C) have proven useful.

Parafins and waxesWaxes and parafins may be titrated directly at 50 °C in a mixture ofmethanol/chloroform. The determination using the drying oven is a furtherpossibility.

Tar and coalTarry products can be dissolved by adding toluene or xylene. The dryingoven can also be used for tar and coal.

General Comments


Applications: Petroleum products



Gasoline 2.5 6 0.0710 0.26 Titrant U 9233 Input: syringe with needleunleaded 50 mL LM F 9230 Stir time: 30 s

Diesel oil 5.0 6 0.0069 2.1 Titrant 2NH Input: syringe with needle20 mL solvent Stir time: 30 s20 mL 1-decanol

Petroleum 4.5 6 0.0077 0.72 Titrant 2NH Input: syringe with needle20 mL solvent Stir time: 30 s20 mL 1-decanol

Motor oil 2.5 6 0.0721 13.4 Composite 2 Evaporate moisture with drying oven40 mL methanol DO302: 140 °C, 200 mL N2/min

Stir time: 600 s

Motor oil 0.3 6 0.2261 0.94 Titrant 2NH Input: syringe with needle20 mL solvent Stir time: 60 s30 mL chloroform

Motor oil 2.5 6 0.0842 9.9 Composite 2 Evaporate moisture with drying ovenused 40 mL methanol DO302: 140 °C, 200 mL N2/min

Stir time: 600 s

Silicon oil 4.0 9 0.0097 0.56 Titrant 2NH Input: syringe with needle20 mL solvent Stir time: 60 s20 mL 1-decanol

Crude oil 2.0 5 0.0206 2.9 Titrant 2NH Input: syringe with needle20 mL solvent Stir time: 60 s30 mL chloroform

multi- 0.2 5 0.338 0.88 Titrant 2NH External solution:purpose 40 mL solvent 3 g in 80 g chloroform,grease 20 min at RT

Input: 5 mL aliquot with syringe

Ski wax 1.5 7 0.0417 1.3 Composite 2 Melt sample at 50 °C25 mL methanol Input: syringe with needle (warm)25 mL toluene Stir time: none

Shoe polish 2.0 5 0.0219 4.9 Composite 2 Melt sample at 50 °C25 mL methanol Input: syringe with needle (warm)25 mL toluene Stir time: none

Reagents:Titrant 2NH: two component reagent HYDRANAL® Titrant 2NH, Riedel No. 34811 (titrant)Solvent: two component reagent HYDRANAL® Solvent, Riedel No. 34800 (solvent)Composite 2: one component reagent HYDRANAL® Composite 2, Riedel No. 34806 (titrant)

Titrant U 9233: two component reagent Titrant U 5 mg H2O/mL, MERCK No. 9233LM F 9230: two component reagent Solvent F (fats and oils), MERCK No. 9230


Comments concerning the applications using DL35

Gasoline, diesel oil,petroleum

The solubility was improved by using 1-decanol or the special solvent foroils and fats instead of chloroform.

Motor oil contains additives to improve its usability. These are zinc-dialkyl-dithiophosphate, calcium sulfonate and magnesium sulfonate. New motoroils contain 5–7% of these additives.Motor oil may be titrated by adding chloroform; however, the resultantvalues are too high due to side reactions with the additives.Reliable values can be obtained by evaporating the moisture in a dryingoven at 140 °C and transferring the vapor into the titration cell with a drypurge gas. At higher temperatures the additives will decompose, which willalso cause errors. The sample is injected through a septum directly into thecrucible using a syringe. The weight is determined by back-weighing.

1-Decanol must be added to the solvent to completely dissolve the sample.After 3 samples the solvent should be replaced, as its dissolving capacitywill be exhausted.

The sample can be dissolved completely only by adding chloroform to thesolvent. 1-Decanol no longer suffices. Replace solvent after each sample,as its dissolving capacity is quickly exhausted.

This fat is incompletely soluble even after adding chloroform. For this rea-son an external extraction with chloroform was used.A determination using the drying oven at 180 °C is a further possibility.At higher temperatures, however, the sample will polymerize.

The sample is melted in a sealed flask at approximately 50 °C. A pre-warmed syringe is used for sample input. The syringe may be warmedusing a hair dryer for instance. This procedure is necessary as the samplewill solidify immediately in a cold syringe.The addition of toluene and heating the titration solution to approx. 30 °Cresults in a suspension which can easily be titrated. The solvent must bereplaced after 3 samples, otherwise the sample will begin to precipitate.This will cover the electrode.The titration solution was kept at 30–35 °C using a thermostatable titrationbeaker (ME-23976) with a circulating water bath.

Motor oil

Silicon oil

Crude oil

Multi-purpose grease

Ski wax, shoe polish


Applications: Petroleum products



Gasoline 0.6 13 769.3 0.5 100 mL Coulomat A Input: syringe with needlesuper 5 mL Coulomat C Stir/Titration time: 0/50 s

Kerosene 2.5 7 36.1 1.4 100 mL Coulomat A Input: syringe with needle(flight benzene) 5 mL Coulomat C Stir/Titration time: 0/75 s

Petroleum dried 0.5 6 43.4 2.5 100 mL Coulomat A Input: syringe with needlewith molecular sieve 5 mL Coulomat C Stir/Titration time: 0/30 s

Hydraulic oil 0.5 6 579.8 2.0 70 mL Coulomat A Input: syringe with needle30 mL chloroform Stir/Titration time: 0/180 s5 mL Coulomat C

Turbine oil 3.0 3 33.5 1.0 70 mL Coulomat A Input: syringe with needle30 mL chloroform Stir/Titration time: 0/180 s5 mL Coulomat C

Transformer 10.0 5 30.4 1.9 100 mL Coulomat A Input: syringe with needleoil 5 mL Coulomat C Stir/Titration time: 0 / 180 s

Brake fluid 0.3 7 1081.2 0.38 100 mL Anolyte Input: syringe with needle5 mL Catholyte Stir/Titration time: 0/210 s

Silicon oil 0.5 6 103.5 1.7 100 mL Coulomat A Input: syringe with needle5 mL Coulomat C Stir/Titration time: 0/50 s

Paraffin 3.0 6 31.0 15.9 100 mL Coulomat A Evaporate moisture with drying ovengranulate 5 mL Coulomat C DO337: 150 °C, 200 mL air/min

Stir/Titration time: 0/900 s

Crude oil 3.0 5 202.0 6.6 100 mL Coulomat A Evaporate moisture with drying oven5 mL Coulomat C DO337: 130 °C, 200 mL air/min


Soot 0.8 5 3582.7 1.5 100 mL Anolyte Evaporate moisture with drying oven5 mL Catholyte DO337: 200 °C, 200 mL N2/min


Standard titration parameters for all titrations:Adjustment: control gain: 5; switch-off criterium: End level 0.1µg/s (0.1 µg H2O/s above drift value)automatic drift determination, automatic titration start

Titration parameters for titrations using DO337 drying oven:Adjustment: control gain: 5; switch-off criterium: fixed titration time and End level 0.05 µg/sautomatic drift determination, manual titration start

Reagents:Coulomat A: anode reagent HYDRANAL© Coulomat A, Riedel No. 34807Coulomat C: cathode reagent HYDRANAL© Coulomat C Riedel No. 34808

Anolyte: anode reagent KF reagent for coulometric water content determination, MERCK No. 9255Catholyte: cathode reagent KF reagent for coulometric water content determination, MERCK No. 9255



Mineral oil products have low moisture contents, sometimes only traces,thus KF coulometry can be particularly recommended.

Coulomat A contains chloroform, thus these samples can be titrated withoutadding chloroform. After 2–3 samples the dissolving capacity of the solventis exhausted and an emulsion results. Even in this condition, correct andreproducible results can be obtained by coulometric titration.

Adding chloroform to these oils gives an emulsion which can be titrateddirectly. The emulsive quality of these heavy oils is not as good as that ofgasoline or petroleum. The titration time is longer and the reproducibilitypoorer.These oils can also be titrated using the drying oven: the moisture is evapo-rated at 130 °C and the vapor transferred into the titration cell using a drypurge gas.

This oil can be titrated directly as an emulsion. The rather low moisturecontent requires a higher sample weight.

Silicon oil can be titrated directly as an emulsion without adding chloro-form. The emulsive quality is very good. The titration time is short, thereproducibility high.

This can be dissolved only in a chloroform/methanol mixture at approx.50 °C. Coulometric determinations at elevated temperatures, however, arenot possible due to limits imposed by the DL37. For this reason the dryingoven is used.When air is used as the purge gas, the drying temperature may not exceed180 °C. At 200 °C the product begins to oxidize after only 10 minutes.The oxidation process releases water. The poor reproducibility is primarilycaused by the inhomogeneity of the sample granules.

Crude oil contains insoluble contaminants that can clog the diaphragm.Thus the drying oven is the method of choice. The sample input of thecrude oil is best achieved by injecting the oil through a septum directly intothe crucible. Weight determination by back-weighing.A direct titration with chloroform addition gives erroneous results:– the sample is merely emulsified and the water released only partially– moisture content too low

(mean from 6 samples = 128.9 ppm, RSD = 0.7%)– black deposit in the titration cell, cell must be cleaned

The coulometric determination using the drying oven is straightforward.A direct determination using volumetric KF titration (DL35) by adding for-mamide or chloroform gives results that are too low, as the soot dissolvesincompletely and the water is only partially released.

Gasoline, kerosine,petroleum

Transformer oil

Silicon oil

Turbine andhydraulic oil

Paraffin

Crude oil

Soot


Karl Fischer TitrationWater Content Determination of Mineral Oil

Sample: 2 g Crude oil

Preparation:Keep sample in a septum flask

Sample Input:Syringe with needle (e.g., ME-71482)

Titrant:KF titrant, 2 mg H2O/mL(HYDRANAL® Titrant 2NH No. 34811)

Solvent:20 mL KF solvent(HYDRANAL® Solvent, No. 34800)30 mL chloroform

Comments:Stir time: 60 secondsSamples with moisture contents in theppm range should be stored in septumflasks. The samples are generally hy-groscopic. The original moisture con-tent is rapidly and significantly alteredby any contact with the ambient (ope-ning the flask, transferring the sample,etc.).After removing the sample from theflask, the pressure difference should becompensated with dry air only.A three-hole adaptor (ME-23982) isrecommended for the sample inputusing a syringe.Replace the solvent after 2 samples, asthe dissolving capacity is exhausted.Titrations of incompletely dissolvedsamples (such as emulsions) give lo-wer results.

Application:Petrochemical industry

Instruments:METTLER DL35 Karl Fischer TitratorElectrode DM 142Matrix printer Epson LX-800

A. Aichert, Application Laboratory, Dez. 1990



6. Plastics and Adhesives

References Muroi, K., Determination of Water in Plastic Materials by Karl FischerMethod, Bunseki Kagaku 11, 351 (1962)

Praeger, K. and Dinse, H.D., Experiences in the Determination of SmallAmounts of Water in Polyethylene and PolyamideFaserforsch. Textiltechn. 21, 37-38 (1970)

DIN 53715 Wasserbestimmung von pulverförmigen Kunststoffen nach KarlFischer

ASTM Designation: D 789-81 Standard Specification for Nylon InjectionMolding and Extrusion Materials

Sharma, H.D. and Subrramanian, N., Determination of Water in Ion-Exchange Resins by Karl FischerAnal. Chem. 41, 2063-2064 (1969)Anal. Chem. 42, 1278-1290 (1970)

van Acker, P., de Cote, F. and Hoste, J., Determination of Water in StrongBase Anion-Exchange Resins by the Karl Fischer TitrationAnal. Chim. Acta. 73, 198-203 (1974)

Glue

General comments PlasticsWater is usually occluded in plastics. It is released very slowly and incom-pletely by diffusion. Most plastics are not soluble in a KF solvent or solventmixture. Therefore the moisture is usually evaporated in a drying oven,then the vapor is driven into the titration cell using a dry purge gas. Externalextraction in methanol, if necessary at 50°C, is also possible.Plastics have low moisture contents (often less than 100 ppm), so that KFcoulometry is especially recommendable.

Ion exchangerIon exchange resins are insoluble in organic solvents. For this reason, thedrying oven is used to evaporate the moisture. The vapor is driven into theKF cell using a dry purge gas.

AdhesivesThe water content of adhesives can be determined directly. In some caseschloroform may be necessary to completely dissolve the sample.


Applications: Plastics and Adhesives



Polyethylene 3.0 6 0.0068 6.9 ReAquant 3.5 Evaporate moisture with drying ovengranules 40 mL solvent Sprint DO337: 280 °C, 200 mL N2/min

Stir time: 600 s

Polyamide 2.0 6 0.5547 0.67 Composite 5 Evaporate moisture with drying ovengranules 40 mL methanol DO302: 190 °C, 200 mL N2/min

Stir time: 900 s

Epoxy resin 0.05 5 0.258 2.6 Titrant 2NH Input: syringe with needlefluid 20 mL solvent Stir time: 60 s

20 mL chloroform

Glue stick 0.05 6 46.3 0.94 Composite 5 Input: spatula20 mL methanol Stir time: 100 s20 mL chloroform

All-purpose glue 0.2 7 1.28 2.2 Titrant 2NH Input: tube with needleCyanoacryl glue 30 mL solvent Stir time: 60 s

Rubber 0.1 6 0.287 5.3 Titrant 2NH External dissolution:cement 10 mL solvent 4 g in 85 g chloroform; 10 min. RT

30 mL chloroform Input: 1 mL aliquot with syringe

Reagents:Titrant 2NH: two component reagent HYDRANAL® Titrant 2NH, Riedel No. 34811 (titrant)Solvent: two component reagent HYDRANAL® Solvent, Riedel No. 34800 (solvent)Composite 5: one component reagent HYDRANAL® Composite 5, Riedel No. 34805 (titrant)

ReAquant 3.5: two component reagent ReAquant® 3.5 mg H2O/mL, J.T.Baker No. 8842 (titrant)Solvent Sprint: two component reagent ReAquant® Solvent Sprint, J.T.Baker No. 8855 (solvent)


Sample Weight Result RSD Reagents Method g n ppm %

Polyethylene 2.0 6 68.7 8.2 100 mL Coulomat A Evaporate moisture with drying ovengranules 5 mL Coulomat C DO337: 180 °C 200 mL air/min


Polypropylene 2.0 6 148.3 5.4 100 mL Coulomat A Evaporate moisture with drying ovengranules 5 mL Coulomat C DO337: 180 °C 200 mL air/min


Polystyrene 2.0 6 322.2 2.4 100 mL Coulomat A Evaporate moisture with drying ovengranules 5 mL Coulomat C DO337: 160 °C 200 mL air/min


PVC foil 0.1 6 638.1 2.2 100 mL Coulomat A Evaporate moisture with drying oven5 mL Coulomat C DO337: 150 °C 200 mL air/min


Standard titration parameters for titrations with drying oven DO337:Adjustment: control gain: 5; (for PVC foil: control gain: 3)switch-off criterium: fixed titration time and End level 0.05 µg/sautomatic drift determination, manual titration start




Polyethylene The sample melts and, once cooled, sticks to the weighing boat. Line theweighing boat with aluminum foil to facilitate sample removal.Due to the low moisture content, the drift must be determined prior to eachsample to ensure a good reproducibility.

The use of too high temperatures for polyamides may result in a continualcondensation reaction which frees water and artificially elevates the watercontent. For this reason, the sample was first tested at 120°C for 2 hours;result: 0.5445%. The temperature was then elevated to 190°C and thetime drastically reduced; result: 0.5547%.

Chloroform was added to the solvent to competely dissolve the sample.After 4 samples the solvent should be replaced, as its dissolving capacitywill be exhausted.

Chloroform must be added to the solvent to ensure that the sample dis-solves completely. All 6 samples can be titrated in the same solvent.

The end of the tube was fitted with an injection needle with a large innerdiameter (1.2 mm) for the sample input.

As the sample is poorly soluble in the solvent/chloroform mixture, it wasexternally dissolved in chloroform.A solvent/chloroform mixture must be used for titration of the solution. Therubber precipitates in pure solvent and will cover the electrode.The solvent must be replaced and the electrode cleaned (deposit on theelectrode) after each titration.


Polyamide

Epoxy resin (fluid)

Glue stick

All-purpose glue(cyanoacryl glue)

Rubber cement

Polyethylene,polypropylene,

polystyrene

PVC foil

When air is used as the carrier gas, the oven temperature may not exceed180 °C. At 220 °C the polyethylene and polypropylene will oxidize in aprocess that generates water.The cooled sample will stick to the weighing boat. Line boat with alumi-num foil to facilitate sample removal.

The foil is cut into approximately 3 cm2 pieces. These will fit easily into thedrying oven crucible. The sample should not touch the inner wall of thedrying oven, as the PVC will stick to it.


Karl Fischer TitrationWater Content Determination of Plastics

A. Aichert, Application Laboratory, Dez. 1990


Sample: 3 g Polyethylene granulate

Preparation:Place sample in drying oven. Evapo-rate moisture and transfer the vaporinto the titration cell with a dry purgegas.Oven temperature: 280 °CPurge gas stream: 200 mL N2/min

Sample input:Weighing boat

Titrant:KF titrant 3.5 mg H2O/mL(ReAquant® Titrant, J.T. BakerNo. 8842)

Solvent:40 mL KF solvent(ReAquant® Solvent, J.T. BakerNo. 8855)

Comments:Stir time: 600 sMETTLER method No. 50The sample melts and, once cooled,will stick to the weighing boat. Lineweighing boat with aluminum foil tofacilitate sample removal.

Application:Polymer industry

Instruments:METTLER DL35 Karl Fischer TitratorElectrode DM142Drying oven METTLER DO302Matrix printer Epson LX-800


7. Medicines (Pharmaceuticals)

General comments In the pharmaceutical industry, moisture contents of active substances, theraw materials required to synthesize these, and the final products them-selves are determined.

Raw materialsThe raw materials used by the pharmaceutical industry are organic andinorganic raw materials as well as solvents. The moisture content determi-nations of these products are described in Chapters 2–4.

Active substancesThe pharmaceutically active substances are generally organic or inorganiccompounds which are soluble in methanol. These can usually be titratedunproblematically. Aldehydes, ketones and some amides require the use ofmethanol-free reagents, as their esterification reactions lead to incorrectlyhigh water contents.

Lyophilized substratesInjectable substances are sometimes delivered as dried substrates, to pro-long the usability of active substances. Here the residual water content is acrucial factor. This water content will be around 100 µg H2O per ampule.

TabletsTablets may contain substances that will react with KF reagents in sidereactions. This is the case for magnesium and aluminum hydroxides, forexample. Both compounds are used as antacids.

Ointments, oils, suppositoriesThe solubility of oils and ointments may be improved by adding chloroformor 1-decanol. The USP XXI recommends a mixture of carbon tetrachloride :chloroform : methanol 2:2:1 for ointments. Suppositories can be dissolvedby adding chloroform and elevating the temperature.

Cachet, T. and Hoogmartens, J., Determination of water in erythromycin byKarl Fischer titration, J. Pharm. Biomed. Anal. ISSN 0731-7085; 6,5,461-472 (1988)

Müller, M., Determination of water in erythromycin by Karl Fischer titration,Dtsch. Apoth. Ztg. ISSN 0011-9857; 127, 41, 2034-2036 (1987)

Use of a simple Karl Fischer apparatus for water determination in lyophil-ized radiopharmaceutical kits, Appl. Radiot. Isot. ISSN 0883-2889; 38,11, 992-993 (1987)

Lindquist, J., Determination of water in penicillins using Karl Fischerreagents, J. Pharm. Biomed. Anal. ISSN 0731-7085; 2,1,37-44, 1984

References


Applications: Medicines



Aspirin 0.2 6 1.53 1.9 Titrant U 9233 Crush sample30 mL LM 9241 Input: weighing boat

Stir time: 600 s

Antibiotics 0.2 6 4.56 1.0 Titrant U 9233 Input: weighing boatdry 30 mL LM K 9221 Stir time: 300 s

2 drops Triton X100 Stir rapidly

Antibiotics 0.03 6 95.8 0.24 Titrant U 9233 Input: syringe with needlesuspension 30 mL LM 9241 Stir time: none

Disinfectant 1.0 6 0.0620 1.5 Titrant 2NH Input: weighing boatpowder 30 mL solvent Stir time: 120 s

Cough drops 0.1 6 6.25 0.13 Titrant U 9233 Input: syringe with needle30 mL LM 9241 Stir time: none

Valerian 0.1 6 29.3 0.14 Titrant 9258 Input: syringe with needleessence 30 mL methanol Stir time: none

Chamomile 0.03 6 43.2 0.12 Titrant 9258 Input: syringe with needleextract 30 mL methanol Stir time: none

Tonic 0.05 6 57.0 0.26 Titrant U 9233 Input: syringe with needle25 mL LM 9241 Stir time: none15 mL formamide

Gel for 0.7 6 42.3 0.51 Titrant U 9233 Input: syringe with needlesprains and 30 mL LM 9241 Stir time: 30 sinfections

Ointment 0.03 5 71.2 0.74 Titrant U 9233 Input: syringe with needlebase 40 mL LM F 9230 Stir time: 30 s

Ointment 0.03 5 54.7 0.40 Titrant U 9233 Input: syringe with needlefor burns 40 mL LM F 9230 Stir time: 60 s

Suppository 1.0 6 0.0023 13.3 Titrant 2NH Input: with tweezers30 mL solvent Stir time: 60 s15 mL toluene Titrate at 50 °C

Reagents:Titrant 2NH: two component reagent HYDRANAL® Titrant 2NH, Riedel No. 34811 (titrant)Solvent: two component reagent HYDRANAL® Solvent, Riedel No. 34800 (solvent)Titrant 9243: two component reagent Titrant 5 mg H2O/mL, MERCK No. 9243Titrant U 9233: two copmponent reagent Titrant U 5 mg H2O/mL, MERCK No. 9233LM 9241: two component reagent Solvent, MERCK No. 9241LM K 9221: two component reagent Solvent K (for ketones and aldehydes), MERCK No. 9221LM F 9230: two component reagent Solvent F (for fats and oils), MERCK No. 9230Titrant 9258 one component reagent Titrant 5 mg H2O/mL, MERCK No. 9258



Aspirin

Antibiotics (dry)

Antibiotics (suspension)

Disinfectant powder

Gels, ointments

Suppositories

The finely crushed sample does not dissolve completely. To ensure thecomplete release of all water, stir for 10 minutes.

This sample is not dense and is poorly wettable with the solvent. Lumpsform which contain undissolved substances. Lump formation can beavoided by adding a detergent (Triton X100) and by stirring vigorously.The sample will then dissolve completely.An elevated post-consumption can be observed when using regular sol-vents. This effect can be eliminated by using a methanol-free solvent.

The direct titration is straightforward.

This powder is insoluble in the KF solvent. A direct titration as a suspensionis possible. Even with a stir time of only 2 minutes, no post-consumptiontakes place, thus the water has been completely released.

Titrate directly.

When using the normal solvent of the two component reagent as well asmethanol, a gel drop forms which immediately deposits itself on theplatinum point of the electrode. This results in an over-titration. By addingformamide this effect can be avoided.

These samples are filled into the back end of a syringe for the sample input.No needle is used due to the sample consistency.The gel dissolves in the solvent of the two component reagent.The complete dissolution of fat-based ointments requires the addition ofchloroform, 1-decanol or the special solvent for fats and oils.

One complete suppository is used for each titration. (The weight is constant:1.0 g). In the solvent/toluene mixture the suppositories dissolve (melt)completely at 50 °C. The solvent must be replaced after 2–3 samples, asthe samples no longer dissolve completely. This leads to a decrease in thereproducibility.

Chamomile extract,couph drops andvalerian extract

Tonic


Applications: Medicines



Massage oil 0.3 6 1059 0.21 100 mL Coulomat A Input: syringe with needle5 mL Coulomat C Stir/Titration time: 0/60 s

Eucalyptus 0.1 6 1267 0.39 100 mL Coulomat A Input: syringe with needleoil 5 mL Coulomat C Stir/Titration time: 0/100 s

Titration parameters:Adjustment: control gain: 5; switch-off criterium: End level 0.1 µg/s (0.1 µg H2O/s above drift value)automatic drift determination, automatic titration start

Sample Lot No. Flask Result Reagents Methodµg H2O

Lyophilized 2BOA 1 771.3 100 mL Coulomat A Dissolve in septum flask withPlasma 2 699.3 5 mL Coulomat C 5 mL titrated Coulomat A

3 759.2 Input: syringe with needle4 665.7 Stir/Titration time: 0/150 s

RRO5 1 720.72 648.73 729.34 619.1

Titration parameters:Adjustment: control gain: 2; switch-off criterium: End level 0.1 µg/s (0.1 µg H2O/s above drift value)automatic drift determination, manual titration start


Eucalyptus andmassage oils


The direct titration is unproblematic. The addition of chloroform is unneces-sary.

An external dissolution of the lyophilisate is not recommendable due to thelow moisture content. The correction factor for the solvent blank is too highcompared to the water content of the sample. Therefore, the followingprocedure is used: approximately 5 mL anolyte are removed from the ano-lyte space of the titration cell with a plastic syringe. This is filled back intothe titration cell. The syringe is rinsed in this manner until it is dry. Then5 mL anolyte are taken up in the syringe and injected through a septuminto the sample flask. The lyophilisate is suspended by shaking the flask(5 minutes in the sonicator). The entire suspension is then pulled back intothe syringe, injected into the titration cell, and the water content is deter-mined.The pressure compensation for sample removal must be achieved usingdry air.

Lyophilized plasma


8. Dyes and Agrochemicals

DyesA large number of dyes are soluble in methanol; these can be titrated easily.Insoluble dyes, such as pigments, can be titrated directly as a suspension.Using this procedure, only the adherent moisture will be determined.A direct titration of water-based dispersion paints and lacquers can also beundertaken. When titrating lacquers, care must be taken in the choice of asolvent. Ketones or reactive amines require the use of a methanol-free sol-vent to prevent interferences caused by side reactions with the KF reagents.

AgrochemicalsAgrochemicals are supplied in solution (with organic solvents), water-based suspensions or as powders.Unpolar solvents are generally used for the solution; thus, the samples canbe completely dissolved only by adding chloroform or 1-decanol. Themoisture content of these is low so that the coulometric method is feasible.The water-based suspensions are best titrated using a direct volumetrictitration.Powders rarely dissolve in most KF solvents. Suspensions of these powdersallow the determination of the adherent moisture only.

General Comments

ASTM D 4017-81 Standard Test Method for Water in Paints and PaintMaterials by Karl Fischer Method

References


Applications: Dyes and agrochemicals


Sample Weight Result RSD Titrant Method g n % % Solvent

Optical 0.3 6 3.87 0.76 Titrant 9258 Input: weighing boatbrightener 30 mL methanol Stir time: 300 s

Wool dye 0.25 6 10.99 0.14 Titrant 9258 Input: weighing boatOrange R 40 mL methanol Stir time: 30 s

Reactive dye 0.3 6 5.24 0.42 Titrant 9258 Input: weighing boatscarlett F-3G 40 mL methanol Stir time: 60 s

Indicator dye 0.6 6 0.928 1.0 Titrant 9258 Input: weighing boatmethanile yellow 40 mL methanol Stir time: 120 s

Dispersion 0.3 6 6.91 0.22 ReAquant 5 Input: weighing boatdye olive 30 mL solvent Sprint Stir time: 300 s

25 mL formamide

Acrylic paint 0.05 6 54.3 0.47 Titrant U 9233 External solution:water based 25 mL LM 9241 3.6 g in 20 mL formamide

15 mL formamide Input: 1 mL aliquot with syringe

Synthetic 1.5 6 0.0906 3.4 Titrant U 9233 Input: syringe with needleenamel 20 mL LM 9241 Stir time: none

20 mL toluene

Insecticide 2.0 6 0.0977 0.56 Titrant 60626 Input: syringe with needlebiological 30 mL LM 60625 Stir time: none

20 mL 1-decanol

Insecticide 2.0 6 0.1461 0.21 Titrant 60626 Input: syringe with needleDiazinon 30 mL LM 60625 Stir time: none

10 mL 1-decanol

Rose fungicide 0.03 6 58.3 0.25 Titrant 60626 Input: syringe with needlewatery emulsion 30 mL LM 60625 Stir time: none

Herbicide 1.0 6 1.20 0.49 Titrant U 9233 Input: weighing boatpowder 30 mL LM 9241 Stir time: 180 s

Insecticide 1.0 6 0.273 2.6 Titrant 60626 Input: weighing boatant killer 30 mL LM 60625 Stir time: 180 s

Reagents:Titrant U 9233: two component reagent Titrant U 5 mg H2O/mL, MERCK No. 9233LM 9241: two component reagent Solvent, MERCK No. 9241Titrant 9258: one component reagent Titrant 5 mg H2O/mL, MERCK No. 9258Titrant 60625: two component reagent Titrant 5 mg H2O/mL, FLUKA No.60626LM 60625: two component reagent Solvent, FLUKA No. 60625ReAquant 5: two component reagent ReAquant® 5 mg H2O/mL, J.T. Baker No. 8844 (titrant)Solvent Sprint: two component reagent ReAquant® Solvent Sprint, J.T. Baker No. 8855 (solvent)




Rose fungicide 0.5 6 828.6 0.36 100 mL Anolyte Input: syringe with needlesolution 5 mL Catholyte Stir/Titration time: 0/90 s

Titration parameters for the titration:Adjustment: control gain: 3; switch-off criterium: End level: 0.1 µg/sautomatic drift determination, automatic titration start

Reagents:Anolyte: anode reagent KF reagent for coulometric water content determination, MERCK No. 9255Catholyte: cathode reagent KF reagent for coulometric water content determination, MERCK No. 9255

Comments concerning the applications

Dispersion dye

Optical brightener

Wool, reactive andindicator dyes

Acrylic paint

Synthetic enamel

Insecticide and rosefungicide (solutions)

This sample is not soluble in KF solvents; it can, however, be suspended.A direct titration with a 5-minutes stir time in methanol is possible. After2 samples, the solvent should be replaced and the electrode cleaned (formsdeposit).

These samples are easily dissolved in methanol. The dissolving capacity ofthe solvent is limited; replace the solvent after 3–4 samples.

This sample is insoluble in KF solvents. It can be titrated directly as asuspension by adding formamide. In pure methanol the water is releasedslowly and incompletely (result: 6.6% with 30 minutes titration time).

A direct titration in a formamide/solvent mixture results in the sample stick-ing to titration cell and electrode, and is not a feasible alternative. Thesample is dissolved in pure formamide and this solution is added to theformamide/solvent mixture. The resulting emulsion can be titrated straight-forwardly (slightly increased post-consumption). Replace the solvent after2 samples.

The sample is added to a prepared toluene/solvent mixture. The resultingfine emulsion can be titrated unproblematically (slightly increased post-consumption). Replace solvent after 2 titrations.

These samples (active agent plus solvent) are soluble only in the presenceof 1-decanol. If an emulsion is prepared, somewhat lower values will result.Due to the low moisture content, a coulometric determination is a furtherpossibility.

The direct tiration is unproblematic.

These samples are insoluble in KF solvents. A direct titration is possible witha 3-minutes stir time. (No elevated post-consumption). After 3 sampleshave been titrated, the water content values decrease (replace solvent).

Rose fungicide(water-based emulsion)

Insecticide andherbicide


9. Detergents and Surfactants

General comments For these products, which are solids, liquids or pastes, a direct KF titrationcan easily be undertaken.Detergents containing hydroxide or perborate result in elevated watercontent values, as these compounds undergo a side reaction with the KFreagent.

ISO 4317-1977 Surface-Active Agents – Determination of Water – KarlFischer Method

References


Detergent for finewashables

Non-ionic-surfactant

This detergent contains perborate, which reacts with the KF reagent in aside reaction. For this reason the moisture is evaporated in the dryingoven at 150 °C and the vapor is transferred to the titration cell by a drypurge gas.

These detergents contain neither hydroxides nor perborates. They can betitrated directly.

These samples dissolve in the solvent. The direct titration is straightforward.Caution: beware of the water dissolving capacity of the KF solvent (replacesolvent after 3–4 samples).

These emulsions can be titrated directly without encountering problems.

The direct titration is straightforward. The coulometric determination canbe used for samples with a low moisture content.

Laundry detergent

Cleaner, dish detergent,soft soap

Fabric softener,impregnation agent




Non-ionic 0.25 6 718.4 0.58 100 mL Anolyte Input: syringe with needlesurfactant 5 mL Catholyte Stir/Titration time: 0/90 snonyl phenyl-ethylene glycol

Titration parameters for all titrations:Adjustment: control gain: 3; switch-off criterium: End level: 0.1 mg/sautomatic drift determination, automatic titration start


Applications Detergents and Surfactants



Laundry 0.1 6 13.7 2.3 ReAquant 5 Evaporate moisture with drying ovendetergent 30 mL solvent DO302: 150 °C, 200 mL N2/min

Stir time: 1200 s

Detergent for 0.2 6 6.13 1.2 ReAquant 5 Input:weighing boatfine washables 30 mL solvent Stir time: 500 s30–60 °CLiquid 0.03 6 81.7 0.60 ReAquant 5 Input: syringe with needledetergent 30 mL solvent Stir time: none

Cleaner 0.03 5 73.9 0.25 ReAquant 5 Input: syringe with needleliquid 30 mL solvent Stir time: none

Dish detergent 0.03 6 73.0 0.39 ReAquant 5 Input: syringe with needleliquid 30 mL solvent Stir time: none

Soft soap 0.03 6 76.4 1.3 ReAquant 5 Input: syringe with needle30 mL solvent Stir time: none

Fabric softener 0.03 6 84.3 0.37 ReAquant 5 Input: syringe with needlecocentrate 30 mL solvent Stir time: none

Impregnation 0.03 6 61.4 0.32 ReAquant 5 Input: syringe with needleagent 30 mL solvent Stir time: 120 s

non-ionic 2.0 6 0.160 0.84 ReAquant 3.5 Input: syringe with needlesurfactant 30 mL solvent Stir time: nonealkylphenylpoly-ethyleneglycol

Reagents:ReAquant 5: two component reagent ReAquant® 5 mg H2O/mL, J.T. Baker No. 8844 (titrant)ReAquant 3.5: two component reagent ReAquant® 3.5 mg H2O/mL, J.T. Baker No. 8842 (titrant)Solvent: two component reagent ReAquant® Solvent Sprint, J.T. Baker No. 8855 (solvent)


10. Silk, Wool, Cellulose, Paper and Wood

General comments

Comments concerning the applications with DL35

Wood

Wool and celluloseWool and cellulose release water easily. Since these products are insol-uble in KF solvents, an external extraction must be performed. Methanol isthe usual solvent for the extraction. The drying oven can also be used.

PaperA low moisture content is a criterium of the quality, especially for insula-tion paper. The KF determination is usually performed by external extrac-tion in methanol or in a methanol/chloroform mixture. If the drying oven isto be used, the temperature should be adjusted to 105–130 °C.

WoodThe KF moisture determination of wood can be achieved using either anexternal extraction in methanol, or the drying oven in the 105–130 °Ctemperature range.

ASTM D 1348-61 Standard Test Method for Moisture in Cellulose

Fujino, H. and Muroi, K., Determination of Water Content in Electric Insu-lation Papers by Karl Fischer Method, Bunseki Kagaku 30, 624 (1981)

References

Wool and silk

Cellulose powder

Wood releases water slowly. A direct titration is not possible. Thus themoisture is evaporated in the drying oven at 140 °C and the vapor istransferred into the KF titration cell using dry nitrogen as the purge gas.At higher temperatures the wood slowly darkens (decomposes slowly),which leads to an increase in the water content.

An external extraction is the method of choice for samples of this nature.

The finely crushed cellulose powder releases water reluctantly. A directtitration can be performed with a 15-minutes stir time, with the samplesuspended in the KF solvent.


Comments concerning applications with DL37The paper samples are cut into pieces of approx. 4–8 cm2. These are placed in the drying ovensample crucible with tweezers.The paper should be stored in a closed container under constant conditions. Ambient conditions(humidity) influence the samples moisture contents considerably.



Copying paper 0.03 6 4.88 1.0 100 mL Coulomat A Evaporate moisture with drying ovenwhite 5 mL Coulomat C DO337: 140 °C, 200 mL air/min


Copying paper 0.06 6 4.98 0.51 100 mL Coulomat A Evaporate moisture with drying ovenrecycled 5 mL Coulomat C DO337: 140 °C, 200 mL air/min


Newspaper 0.04 6 7.04 0.53 100 mL Coulomat A Evaporate moisture with drying oven5 mL Coulomat C DO337: 140 °C, 200 mL air/min


Insulation 0.05 6 6.41 0.6 100 mL Coulomat A Evaporate moisture with drying ovenpaper 5 mL Coulomat C DO337: 140 °C, 200 mL air/min


Titration parameters for titrations using DO337 drying ovenAdjustment: control gain: 5; switch-off criterium: fixed titration time and End level 0.05 µg/sautomatic drift determination,manual titration start


Applications: Silk, wool, cellulose, paper, wood



Wood (pine) 0.5 6 8.28 0.70 Titrant 9258 Evaporate moisture in drying oven40 mL methanol DO302: 140 °C, 200 mL N2/min

Stir time: 900 s

Virgin wool 0.08 6 9.84 0.24 Titrant U 9233 External extraction.30 mL LM 9241 2.1 g in 52 g methanol, 1 h at RT


Silk 0.07 6 6.83 0.35 Titrant U 9233 External extraction:30 mL LM 9241 1.1 g in 42 g methanol, 1 h at RT


Cellulose 0.2 6 4.23 0.66 Titrant U 9233 Input: weighing boatpowder 30 mL LM 9241 Stir time: 15 minutes

Reagents:Titrant U 9233: two component reagent Titrant U 5 mg H2O/mL, MERCK No. 9233LM 9241: two component reagent Solvent, MERCK No. 9241Titrant 9258: one component reagent Titrant 5 mg H2O/mL, MERCK No. 9258


11. Building Materials and Minerals

General Comments

References Lindner, B. and Rudert, V., Verbesserte Methode zur Bestimmung von ge-bundenem Wasser in Mineralien, Gesteinen und anderen Feststoffen,Fresenius Z. Anal. Chem. 248, 21-24 (1969)

Rechenberg, W., Bestimmung des Wassergehaltes in Zement,Zement-Kalk-Gips 29, 512-516 (1976)

Farzaneh, A. and Troll, G., Quantitative Methode zur Bestimmung vonWasser in Mineralien, Gesteinen und anderen Feststoffen,Fresenius Z. Anal. Chem. 287, 43-45 (1977)

Most minerals and building materials such as cement, plaster of paris andlime cannot be titrated directly, as the water is chemically bound. A furtherhindrance is that oxides or carbonates will undergo a side reaction withthe KF reagents. For these reasons, the water is evaporated in the dryingoven and the vapor then transferred into the KF cell by a dry purge gas.

ZeolitesZeolites are silicates with a three-dimensional structure composed of SiO4and AlO4 molecules with characteristically dimensioned canals and hol-low spaces. These occur naturally; most, however, are synthetic. They areused as molecular sieves (for the partitioning of small molecules such asH2O, NH3, H2S, etc.), ion exchangers (for cations), boiling chips, cata-lysts (for gas-phase reactions) and as detergents. The zeolites tightly bindwater in the spaces. Water is released stepwise at successively highertemperatures. The release is complete at 300–350 °C.


Applications: Building Materials and Minerals



Plaster of 0.5 6 6.04 0.5 Titrant 9258 Evaporate moisture with drying ovenparis 40 mL methanol DO302: 300 °C, 200 mL, N2/min

Stir time: 600 s

Knifing filler 0.5 5 5.49 1.2 Titrant 9258 Evaporate moisture with drying oven40 mL methanol DO302: 300 °C, 200 mL, N2/min

Stir time: 900 s

Zeolite S90 0.3 6 12.4 0.43 Titrant 9258 Evaporate moisture with drying ovenground 40 mL methanol DO302: 300 °C, 200 mL, N2/min

Stir time: 600 s

Reagent:Titrant 9258: one component reagent Titrant 5 mg H2O/mL, MERCK No. 9258

Cement

Zeolite

Plaster of paris

Knifing filler




Cement 0.4 6 0.820 2.2 100 mL Anolyte Evaporate moisture with drying oven5 mL Catholyte DO337: 300 °C, 200 mL, N2/min


Titration parameters for titrations with DO337 drying oven:Adjustment: control gain: 5; switch-off criterium: fixed titration time or End level 0.05 µg/sautomatic drift determination, manual titration start


Plaster releases the water slowly. A direct titration of the suspension insolvent is still possible though. After a stir time of 25 minutes, nearly thesame moisture content (5.8 %) was determined using this method aswas obtained with the drying oven (6.0 %).

The filler binds water tightly. The water is not released completely in a di-rect titration (result of a direct titration with a 75-minutes stir time: 2.4%).Due to the tight binding of the water, the sample must be heated to 300 °Cfor 15 minutes in the drying oven.

Zeolite releases water completely at temperatures higher than 300 °C.Drying temperature: 300 °C, drying time: 10 minutes.

Cement contains CaO which reacts with the KF reagent. Therefore themoisture is evaporated in the drying oven at 300 °C and the vapor istransferred into the titration cell using a dry purge gas. The coulometricmethod is used due to the low moisture content.


12. Index of Reagents

Reagent Riedel-de Haën E. MERCK Fluka AG J.T. Baker Ericsen/GFS(all pyridine-free) HYDRANAL®

Two-component reagentTitrant 5 mg H2O/mL 34801 9243 60626 8844 1604Titrant 3,5 mg H2O/mL — — — 8842 —Titrant 2 mg H2O/mL 34811 — — — 1603Titrant 1 mg H2O/mL — — — — 1602Solvent 34800 9241 60625 8855 1610Solvent for fats and oils 34812 9230 — — —

Two-component reagentfor ketones and aldehydesTitrant 5 mg H2O/mL — 9233 — 8844 1604Titrant 2 mg H2O/mL — — — — 1603Solvent — 9221 — 8840 1609

One-component reagentTitrant 5 mg H2O/mL 34805 9258 60623 — 1600Titrant 2 mg H2O/mL 34806 — — — 1601Titrant 1 mg H2O/mL 34827 — — — 1606Anhydrous methanol 34940 6012 65546 8047 814/1240

One-component reagentfor ketones and aldehydesTitrant 5 mg H2O/mL 34816 — — — 1600Titrant 2 mg H2O/mL — — — — 1601Solvent 34817 — — — 1608

Reagents for coulometricKF titrationAnolyte 34807 9255 — — 1612Katholyte 34808 9255 — — 1613

Reagents for coulometricKF titration (for ketones)Anolyte 34820 — — — 1619Katholyte 34821 — — — —

Titre standardsdisodium tartrate dihydrate • 2 H2O 34803 6664 71994 0317 805Standard 5 mg H2O/mL 34813 9259 — — 1617Standard 1 mg H2O/mL 34828 — — — 1618Methanol 5 mg H2O/mL 34802 — — — —

Standards forpH-adjustmentBuffer 5 mmole acid/mL 34803 — — — 1615Benzoic acid 18102 136 12349 1270 673Salicylic acid 27301 635 84210 0251 799Imidazole 63561 4716 56750 1747 —

Auxiliary solventsChloroform 32286 2445 25690 9257 816/1234Methanol 32213 6009 65546 8047 814/12401-Dodecanol 62411 803463 30610 — —1-Propanol 33538 997 82090 8397 —Toluene 32249 8325 89681 8078 1052/1245Formamide 62608 9684 47670 7042 1093

Bottle adaptore METTLER unnecessary ME-23774 ME-23817 unnecessary unavailable


Index of Suppliers

Headquarters:Wunstorfer Strasse 40PostfachD-3016 SeelzeTel. (0 51 37) 7 07 0Telefax (0 51 37) 9 19 79

Headquarters:Postfach 4119D-6100 Darmstadt 1Frankfurter Strasse 250Tel. (06151) 72 0Telefax (06151) 72 33 68

Headquarters:Fluka Chemie AGPostfach 172CH-9470 BuchsIndustriestrasse 25Tel. 085 6 95 11Telefax 085 6 54 49

Headquarters:J. T. Baker Inc.222 Red School LanePhillipsburgN.J. 08865Tel. 908-8592151Telefax 908-859 2865

Headquarters:GFS ChemicalsP.O. Box 245PowellOH 43065Tel. (US) 800-858-9682Tel. (outside US) 614-881-5501Telefax 614-881-5989

E. MERCK

Fluka AG

Riedel-de Haën AG

J.T. Baker

Ericsen/GFS


13. Hazards and waste disposal tips

One-component reagentContains: sulfur dioxide, iodine, base (imidazole) and solvent (methanol,2-methoxyethanol or diethyleneglycolmonomethylether).Safety precautions: flammable to extremely flammable. Irritant when inhaled. Health hazard wheninhaled, swallowed or allowed to contact skin. Keep container tightly closed. Keep away from openflames or sparks. Do not let reagent contact skin or eyes.Disposal: as an organic solvent.

Two-component reagent:This titrant contains: iodine and solvent (methanol, 2-methoxyethanol, xylene or trichloroethylene).The KF-solvent contains: sulfur dioxide, base (imidazole) and solvent (methanol,2-methoxyethanol or diethyleneglycolmonomethylether).Safety precautions: flammable to extremely flammable. Irritant when inhaled. Health hazard wheninhaled, swallowed or allowed to contact skin. Keep container tightly closed. Keep away from openflames or sparks. Do not let reagent contact skin or eyes.Disposal: as an organic solvent.

Reagents for coulometry:This reagent contains iodide, sulfur dioxide, base (imidazole), and solvent (methanol, chloroform,tetrachloromethane, 2-methoxyethanol).Safety: Highly flammable. Skin irritant. Poisonous when inhaled or swallowed. Keep container tightlyclosed and far removed from open flames or sparks. Do not let reagent contact skin or eyes.Disposal: as an organic solvent.

Safety data for the KF-components and auxiliary solvents:sulfur dioxide: MAK-value: 200 ppm

iodine: MAK-value: 0.1 ppm, oxidantdiethyleneglycol-

monomethylether: Flashpoint: 87 °C2-methoxyethanol: Flashpoint: 46 °C, MAK value: 5 ppm

Flammable. Potential teratogen.Health hazard when inhaled, swallowed or allowed to contact skin.Irritant when inhaled.

methanol: Flashpoint: 11 °C, MAK value: 200 ppmHighly flammable. Poisonous when inhaled or swallowed.

o-xylene: Flashpoint: 28 °C, MAK value: 100 ppmFlammable. Health hazard upon inhalation.

chloroform: Flashpoint: does not burn, MAK value: 200 ppmHealth hazard when inhaled. Irreversible damage possible.

1-decanol: Flashpoint: 95 °C, Irritant for skin and eyes.formamide: Flashpoint: does not burn, MAK value: 20 ppm

Irritant for skin and eyes. Potential teratogen.toluene: Flashpoint: 6 °C, MAK value: 20 ppm

Extremely flammable. Health hazard upon inhalation.


Acetaldehyde 16,18Acetic acid 16Acetone 16,18Acetonitrile 16Acetophenone 10,12Acrylic paint 36Adhesives 27–30Agrochemicals 35–37Aluminum oxide 6Aluminum powder 6,8Aniline 10,12Antibiotics 32Aspirin 32Benzaldehyde 10,12Benzamide 12Benzyl alcohol 10,12Brake fluid 24Calcium chloride 6Calcium oxide 6Cellulose 41Cement 43Chamomile extract 324-Chlorotoluene 10,12Cleaner liquid 39Cough drops 32Crude oil 22,24,26Cyanoacryl glue 28Cyclohexene 16,18Detergents 38–39Diesel oil 22Diethylether 16,18Dimethylformamide 16,18Dish detergent 39Disinfectant 32Dispersion dye 36Dyes 35–37Epoxy resin 28Ethylene glycol 16,18Ethyl acetate 18Ethylen chloride 18Eucalyptus oil 34Fabric softener 39Fats 21–25Fungicide 35,37Gasoline 22,24Gel for sprains 32

Glue stick 28Grease 22Herbicide 36Hydraulic oil 24Impregnation agent 39Indicator dye 36Insecticide 36Insulation paper 41iso-Amyl alcohol 16Isobutylmethylketone 16,18Isopropyl alcohol 18Kerosene 24Knifing filler 43Laundry detergent 39Liquid detergent 39Lithium chloride 6Lyophilized Plasma 34Magnesium oxide 6Massage oil 34Medicines 31–33Methyl benzoate 10,12Methylene chloride 16Mineral oil 21–25Minerals 43Motor oil 22n-Butylamine 10,12n-Hexane 18,20Naphtaline 122-Nitrophenol 10Non-ionic surfactant 39Ointment 32Optical brightener 36Oxalic acid 10Paint 36Paper 41Paraffin 24Petroleum 22,24Petroleum Products 21–25Phenol 12,14Phosphoric acid 6Plaster of paris 43Plastics 27–30Polyamide 28Polyethylene 28,30Polypropylene 28Polystyrene 28

PVC 28Reactive dye 36Rubber cement 28Salicylic acid 10,12Shoe polish 22Silicon oil 22,24Silk 41Skiwax 22Sodium carbonate 6Sodium chloride 6Soft soap 39Soot 24Sulfuric acid 6Suppository 32Surfactants 38–39Synthetic enamel 36Tonic 32Toluene 16,18Transformer oil 24Turbine oil 24Urea 10Valerian essence 32Waxes 21–25Wood 41Wool 41Wool dye 36Zeolite 43

14. Sample Index


Notes


This application bulletin represents selected, possible application examples. These have been tested with allpossible care in our lab with the analytical instrument mentioned in the bulletin. The experiments wereconducted and the resulting data evaluated based on our current state of knowledge.

However, the application bulletin does not absolve you from personally testing its suitability for your intendedmethods, instruments and purposes. As the use and transfer of an application example are beyond our control,we cannot accept responsibility therefore.

When chemicals and solvents are used, the general safety rules and the directions of the producer mustbe observed.

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Subject to technical changes© 09/04 Mettler-Toledo GmbH, ME-00724354Printed in Switzerland on 100% chlorine-freepaper, for the sake of our environment.

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SK Mettler-Toledo, SK-82104 BratislavaTel. +421-7-4342 7496, Fax +421-7-4333 7190

SI Mettler-Toledo, d.o.o., SI-1236 TrzinTel. +386-61-162 18 01, Fax +386-61-162 17 89

TH Mettler-Toledo (Thailand) Ltd., Bangkok 10310Tel. +66-2-719 64 80, Fax +66-2-719 64 79

TW Mettler-Toledo Pac Rim AG, TaipeiTel. +886-2-2579 5955, Fax +886-2-2579 5977

UK Mettler-Toledo Ltd., Leicester, LE4 1AWTel. +44-116-235 70 70, Fax +44-116-236 63 99

US Mettler-Toledo, Inc., Columbus, OH 43240Tel. +1-614-438 4511, Fax +1-614-438 4900

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