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METTLER TOLEDO TItrators

Karl Fischer ApplicationsFood, Beverages, Cosmetics

METTLER TOLEDO Karl Fischer Titration Applications 3

Contents 1. Introduction

2. Sugar and sugar productsSamples: saccharose, cane sugar, honey, jelly, jam, chocolate, Ovomaltine®.Application example: direct titration of honey

3. Fats, oils and dairy productsSamples: edible oil, butter, margarine, milk powders, yoghurt, ice cream, ca-sein, cheese.Application example: coulometric titration of edible oil.

4. Grains, starchy foodsSamples: flour, dough, Zwieback®, biscuit, cereals, noodles, potato flakes.Application example: KF titration of Zwieback® using the drying oven.

5. Spices and dehydrated productsSamples: pepper, curry, salt, mixed spice, spiced sauce, mustard, ketchup,dehydrated chives, instant coffee.Application example: external extraction of ground curry.

6. Various foodtuffsSamples: hazelnuts, cocoa powder, tea, coffee beans, tobacco, liver sausage,broth, instant pudding powder, chocolate flavour.

7. Beverages and concentratesSamples: cognac, beer, wine, liquor, orange juice, tomato juice, black currantsyrup, instant ice tea, isotonic drink powder.

8. CosmeticsSamples: shampoo, after-shave, day cream, sun lotion, lipstick, massage oil,toothpaste.

9. Reagent index

10. Supplier index

11. Hazards and waste disposal tips

Karl Fischer Water Content Determinationin Food, Beverages and Cosmetics

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® Manual, Fifth 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 TOLEDO Karl Fischer Titration Applications4

1. Introduction

The quality and often the usability of many foodstuffs and cosmetics frequentlydepend crucially on the water content. Control and optimization of the product qualitythus require that the water content should be determined regularly.

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, has manysystematic errors, is inefficient and slow.

The method developed by Karl Fischer, in which water is titrated in the presence ofsulfur dioxide and an organic base [1], was improved significantly by E. 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 react to form methyl sulfite[RNH]SO3CH3 , as it has been recently shown.

The pyridine used initially by Karl Fischer has been replaced by more suitable amines.Several companies supply pyridine-free Karl Fischer reagents with a constant titre.

Microprocessor controlled METTLER DL18 and DL35 Karl Fischer titrators as well asMETTLER DL37 KF Coulometer allow water contents to be determined rapidly, easilyand reproducibly. The volumetric DL35 and DL18 KF titrators are recommended forwater contents ranging from ppm to 100%, whereas the coulometric DL37 KF titratoris useful for trace moisture content determinations.

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

Gases and liquids are generally easily dissolved in methanol, the usual solvent forKarl Fischer titration. Solids, however, may contain water as water of crystallization,occluded water or as adherent moisture. For this reason, sample preparation is ofgreat importance for the analysis. A total water content determination requires thatthe sample is completely dissolved. Should this not be possible in methanol, it maybe necessary to add decanol, chloroform, formamide or other solvents. In certaininstances titration at elevated temperatures, at the boiling point, or after externalextraction may be helpful.

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

The differential availability of the water may be used to selectively quantify only theadherent moisture (e.g. for carbohydrates). It is, however, necessary to prevent therediffusion 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. Sugar and Sugar Products

References: Zürcher, K. and Hadorn, H., "Störungen bei der Wasserbestimmung nachKarl Fischer", Mitt. Gebiete Lebensm. Hyg. 72, 177-182 (1981).

Scholz, E., "Wasserbestimmung in Lebensmitteln", Deut. LebensmittelRundschau 79, 302-306 (1983).

Schneider, F., Emmerich, A., and Ticmanis, U., "Die Bestimmung der Ober-flächenfeuchte von Zucker", Zucker 28, 349-536 (1975).

Sugar Analysis, ICUMSA, 1979.

Kreiser, W.R., and Martin, R.A., "Comparison of Accuracy, Precision, andSpeed of Three Methods for Determining Moisture in Milk Chocolate",J. Assoc. Off. Anal. Chem. 60, 303-306 (1977).

In general Included water is released very slowly from undissolved sugar products. Thus,for a total water content determination, the sample needs to be dissolvedcompletely. This may be achieved by adding formamide to the KF solvents andby titrating at higher temperature.

Caution: Certain carbohydrates decomposes slowly in a process that generateswater at temperatures higher than 50°C. The use of more than 50% formamideis not recommended, as the stoichiometryof the Karl Fischer reaction will bealtered.

The adherent moisture of saccharose is generally more interesting than the totalwater content, as the adherent moisture influences the sugar flow. The samplemust not be dissolved and the included water should not diffuse out for thedetermination of the adherent moisture. This may be achieved using a mixtureof chloroform/methanol as the solvent, and by performing teh titration rapidly.

Products containing chocolate require the addition of chloroform to dissolvefats. Candy, caramels or toffees, marzipan and wine gum may necessitate theaddition of formamide and/or titration at elevated temperatures


Applications: Sugar and Sugar Products

A) Volumetric determination using DL35

Sample Weight Result RSD Titrant Methodg n % % Solvent

Cane sugar 4.0 6 0.0503 5.0 Composite 1 Sample input: weighing boatadherent moisture 10 mL methanol Start titration immediately

40 mL chloroform Switch-off delay: 7 s

Cane sugar 2.0 6 0.155 5.8 Titrant 5 Sample input: weighing boattotal water 20 mL solvent Stir time: 900 s

20 mL formamide Titrate at 50°CFrench honey 0.1 6 16.2 0.43 Titrant 5 Sample input: syringe without needle

30 mL solvent Stir time: 240 s

Raspberry jelly 0.03 7 35.4 0.28 Titrant 5 Sample input: syringe without needle30 mL solvent Stir time: 300 s

Four-fruit jam 0.07 8 35.5 0.25 Titrant 5 Sample input: syringe without needle30 mL solvent Stir time: 240 s20 mL formamide

Milk chocolate 0.3 6 1.44 3.4 Titrant 5 Grate sample finely20 mL solvent Sample input: weighing paper10 mL chloroform Stir time: 600 s

Ovomaltine® 0.3 8 5.8 0.74 Titrant 5 Sample input: weighing paper20 mL solvent Stir time: 400 s20 mL formamide

Reagents:Titrant 5: two component reagent HYDRANAL® Titrant 5, Riedel No. 34801 (titrant)Solvent: two component reagent HYDRANAL® Solvent, Riedel No. 34800 (solvent)Composite 1: one component reagent HYDRANAL® Composite 1, Riedel No. 34827 (titrant)

B) Coulometric determination using DL37

Sample Weight Result RSD Reagents Methodg n ppm %

Saccharose 0.2 6 71.5 4.2 100 mL Coulomat A External extraction: 10 g in 55 gadherent moisture 5 mL Coulomat C chloroform; 15 min at 25°C

Sample input: 3 mL aliquot, syringewith nedleStir/Titration time: 0/40 s

Saccharose 0.1 7 533.7 4.7 100 mL Coulomat A External dissolution: 6 g in 60 gtotal water 5 mL Coulomat C formamide; 15 min at 50°C

Sample input: 1 mL aliquot, syringewith needleStir/Titration time: 0/65 s

Titration parameters:Adjustment: control gain = 5, End level = 0.1 µg/s (0.1 µg H2O/s over drift)Automatic drift determination; Automatic titration start

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


Comments on the Applications

Ovomaltine®

Saccharose

Cane sugar(adherent moisture)

Honey

Cane sugar(total water)

Raspberry jelly

Four-fruit jam

Even with 80% chloroform in the solvent, the partial solubility of the sugar andthe diffusion of water cannot be prevented completely (subsequent consump-tion). Thus, the titration must be performed rapidly. The switch-off delay isreduced to 7 seconds.

To ensure that the sugar dissolves completely, the solvent must contain 50%formamide and the titration must be performed at 50°C.Replace the solvent after 3 samples as the dissolving capacity of the solventwill be so low that the 15 minute stir time will not be enough for solubilizationof the sugar sample. Increasing the quantity of formamide in the solvent toenhance the solubility is not recommended as the stoichiometry of the KarlFischer reaction will be altered.

Honey dissolves in the HYDRANAL® solvent, thus formamide needs to be addedto the solvent. Using the indicated solvent amount, 6 determinationscould beperformed successively.

The jelly dissolves in the HYDRANAL® solvent provided that the stir time issufficient. Using the indicated amount of solvent, 7 determinations could beperformed successively.

The jam could be dissolved to completion only ba adding formamide and bystirring longer. The time required for one titration was 6-8 minutes.

The chocolate could be dissolved only by adding chloroform. The directtitration has a sluggish endpoint and a high subsequent consumption.Titration time: 10-15 minutes.

Ovomaltine® can be dissolved in the presence of formamide. After 3 samplesrenew the solvent as its dissolving capacity will be exhausted.Direct titration of Ovomaltine® shows a sluggish endpoint and a highsubsequent consumption.Titration time: 10-15 minutes.

For the coulometric KF titration, the water content of solids must be determinedusing external extraction, external dissolution or with the drying oven. Sincesaccharose is not thermally stable the drying oven cannot be used.By a short external extraction with chloroform, practically only the surfaceadherent moisture will be affected. Water diffusion can be neglected. At 50°Csaccharose can be dissolved completely in formamide. Using this method, thetotal water content can be determined.

Milk chocolate


Karl Fischer TitrationWater Content Determination of Honey

A. Aichert, Application Laboratory, Nov. 1990

Method:

Sample: 0.15 g Swiss Honey

Preparation:Heat sample in a closed vessel (35°C)and homogenize well. Fill in sample inthe syringe from the back side.

Sample Input:Syringe without needle(eg. ME-71492)

Titrant:KF titrant 5 mg H2O/mL(Fluka AG, No. 60626)

Solvent:30 mL KF solvent(Fluka AG, No. 60625)

Remarks:METTLER Method KF46Stir: 300 seconds

Application:Quality control food industry

Instruments:METTLER DL35 Karl Fischer TitratorElectrode DM142Dot matrix printer Epson LX-800

Result und Statistics:


3. Fats, Oils and Dairy Products

References International Standard FIL/IDF 23: 1964, "Wasserbestimmungen in Butterölmit der Karl Fischer Methode", Milchwirtschaft 21, 137-139 (1966)

Zürcher, K. and Hadorn, H., "Wasserbestimmung nach Karl Fischer an ver-schiedenen Lebensmitteln", Deut. Leb. Rundschau 77, 343-355 (1981)

Scholz, E. , "Wasserbestimmung in Lebensmitteln", Deut. LebensmittelRundschau 79, 302-306 (1983)

Strange, T.E., "Collaborative Study of Moisture in Cheese by Gas Chromato-graphy and by Karl Fischer Titration"J. Assoc. Off.Anal. Chem. 55, 507-510 (1972)J. Assoc. Off.Anal. Chem. 53, 865-868 (1970)

Rüegg, M. et al., "Die Bestimmung des Wassergehalts in Milch und Milch-produkten mit der Karl-Fischer-Methode"Mitt. Gebiete Lebensm. Hyg. 77, 131-138 and 139-146 (1986)Mitt. Gebiete Lebensm. Hyg. 77, 446-451 and 535-543 (1986)Mitt. Gebiete Lebensm. Hyg. 78, 309-316 (1987)

In general Water content determinations of fats and oils are unproblematic once theappropriate solvent has been found. Chloroform as a cosolvent has proven tobe useful. MERCK recommends the use of a special solvent mixture (MERCKNo. 9230) for fats and oils for environmental reasons.Milk and milk powders can be titrated directly in methanol. Milk powderrequires a longer stir time (5-10 minutes), and for high-fat milk powder theaddition of chloroform is recommended. Fats (such as butter and margarine)and milk products (i.e. yoghurt, curd) generally do not have homogeneouswater distributions. To ensure precise measurements, mechanical homogeni-zation of the samples is a must. Larger sample sizes also improves thereproducibility, however, necessitate an external dissolution so that the amountof water to be titrated can be aliquoted to reasonable sample sizes.When titrating certain vegetable oils, a slightly increased subsequent con-sumption that may be caused by a side rection has been observed. Should thisbe the case, a reduction of the switch-off delay to 5-10 seconds is recommen-ded.The titration of cheese is difficult as the water is distributed unevenly, the sampleis barely soluble and it is difficult to extract the water. E. Scholz recommendstitration of the finely grated sample at 50°C in a solvent mixture (methanol/formamide). External extraction of the sample with propanol in the mixer isanother possibility.


Applications: Fats, Oils and Dairy Products



Sunflower oil 3.0 7 0.0767 1.2 Titrant 9243 Input: syringe without needle40 mL LM 9230 Stir time: 60 s

Butter 0.2 6 15.3 0.47 Titrant U 9233 Input: syringe without needle25 mL LM 9241 Stir time: 300 s20 mL 1-decanol

Margarine 0.03 6 58.2 0.25 Titrant 9243 External extraction: 1.5 g in"Minarine" 30 mL LM 924 50 mL 1-decanol/methanol 4:1;

20 min. at 25°CInput: 1 mL aliquot with syringeStir time: 20 s

Milk powder 0.05 6 5.09 0.67 Titrant 9243 External extraction: 2 g in 50 mL30 mL LM 9241 formamide; 30 min at 25°C

Input: 1 mL aliquot with syringeStir time: none

Yoghurt, plain 0.03 6 86.3 0.22 Titrant 9243 Homogenize for 3 min with mixer30 mL LM 9241 Input: syringe with needle

Stir time: 60 s

Ice cream 0.02 6 66.5 0.28 Titrant 9243 Homogenize well30 mL LM 9230 Input: syringe without needle

Stir time: 60 s

Casein 0.1 6 10.3 0.46 Titrant U 9233 Input: weighing boat30 mL LM 9241 Titrate at 40-45°C30 mL formamide Stir time: 300 s

Cheese 0.025 6 27.6 0.42 Titrant 9243 External extraction: 1.5 g in 50 mLgrated 20 mL LM 9241 1-decanol/formamide/methanol

8:2:1 ; 2 hours at 25°CInput: 1.5 mL aliquot with syringeStir time: 60 s

Reagents:Titrant 9243: two-component reagent (titrant) 5 mg H2O/mL MERCK No. 9243Titrant U 9233: two-component reagent (titrant U) 5 mg H2O/mL MERCK No. 9233LM 9241: two-component reagent (solvent) MERCK No. 9241LM 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



Rape oil 1.0 4 424 0.88 75 mL Coulomat A Input: syringe with needle25 mL chloroform Stir/Titration time: 60/130 s5 mL Coulomat C

Titration parameters:Adjustment: control gain = 5, End level = 0.1 µg/s (0.1 µg H2O/s over drift)Automatic drift determination; Automatic titration start



Edible oil


Solvent F (MERCK) or 1-decanol can be used in place of chloroform; the latter,however, dissolves the oil in a better way. When using solvents other thanchloroform, the solvent mixture should be replaced after few samples. Thecoulometric method is also well suited for edible oils. In spite of the smallersample weight, the reproducibility is better than that obtained by the volumetricprocedure.

Water is distributed very unevenly in butter. For this reason the sample ishomogenized thoroughly at 25-30°C and is kept in a tightly sealed vessel.Before each determination, the top layer is skimmed off and the sample isremoved from the lower product (The moisture on the butter surface willdecrease slowly, as some of it is released into the ambient). The sample isremoved with a spatula and transferred into a titration cell. Do not use syringesor similar devices, as the mechanical shear may drive water drops from thesample. The external extraction with methanol/1-decanol gives better repro-ducibility (for 6 samples, RSD = 0.29) but requires much greater effort.

Direct titration in 1-decanol/methanol 1:1 is possible, but the reproducibilityis poor. Due to the high water content, using small samples is sensible althoughefen small inhomogeneities will cause greta variation in th eresults. Theexternal extraction method is easily performed and gives reproducible results.

The two-component reagent can be used for a direct titration by adding TritonX-100 (surfactant), RSD = 1.8%.Using the drying oven (20 min at 120°C) the values obtained are somewhathigher, and the repeatability expresses as RSD is 2.6%. The external extractionworks well and gives the most reproducible results.

Water is distributed unevenly in yoghurt. Homogenize the sample well with ahand mixer.

Water is distributed unevenly in yoghurt. Homogenize the sample thoroughlyat room temperature in a closed vessel with a hand mixer.

This can be titrated directly at 40-50°C by adding formamide (max. 50%).After stirring for 5 min, the sample is dissolved completely. Replace the solventmixture after 3 samples, as the dissolving capacity will be exhausted.

Grated cheese cannot be dissolved in the KF solvents. It is possible to titrate afinely grated sample by adding formamide and titrating at 50°C. The cheesecan be dissolved completely in the solvent mixture 1-decanol/formamide/methanol 8:2:1 (decanol for the fats, formamide for the proteins and methanolas the solvating agent).This solvent mixture was used to dissolve the sample. This solution consists oftwo distinct liquid phases and thus it must be stirred vigorously while takingsample aliquots.

Butter

Margarine("Minarine")

Milk powder

Yoghurt

Ice cream

Casein

Grated cheese


Dr. R. von Rotz, Application Laboratory, Oct. 1990

Karl Fischer TitratrionWater Content Determination of Edible Oil

Sample: 1 g Rape oil

Method:Preparation:Keep sample in septum flask

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

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

Anolyte:75 mL Anolyte(HYDRANAL® Coulomat A, No. 34807)

Solution:25 mL Chloroform

Remarks:Stir time: 60 sWhen taking the sample the pressurecompensation has to be made by driedair only.Titration time: 70 s


Instruments:METTLER DL37 KF Coulometer

Result and Statistics:


References Zürcher, K. and Hadorn, H.,"Wasserbestimmung in Lebensmitteln nach der Karl Fischer Methode",1. Teil, Deut. Lebensmittel Rundschau 74, 249-259 (1978)2. Teil, Deut. Lebensmittel Rundschau 74, 287-296 (1978)

Zürcher, K. and Hadorn, H.,"Wasserbestimmung nach Karl Fischer an verschiedenen Lebensmitteln",Deut. Lebensmittel Rundschau 77, 343-355 (1981)

Hadorn, H.,"Ringversuche zur Wasserbestimmung in Lebensmitteln nach Karl Fischer",Mitt. Gebiete Lebesm. Hyg. 71, 220-235 (1980)

Scholz, E.,"Wasserbestimmung in Lebensmitteln",Deut. Lebensmittel Rundschau 79, 302-306 (1983)

Starch Hydrolysis Products - Determination of Water Content(Modified Karl Fischer Method), ISO / DIS 5381

4. Grains, Starchy Foods

In general All these foodstuffs are insoluble in the usual solvents and release water onlyvery slowly.Fine milling of coarse grains allows the water to be released more completely.Most of these products may be titrated directly at an elevated temperature (upto 50°C) in the presence of formamide. Also recommended is externalextraction with methanol or formamide (in some cases at elevated tempera-tures).

Caution:Baked goods containing carbohydrates may undergo thermal decompositionat elevated temperatures (greater than 50°C)in a process that generates water.Using more than 50% formamide is not recommended, as the stoichiometryof the Karl Fischer reaction will be altered.


Applications: Grains, Starch Foods



All-purpose flour 0.3 5 12.1 0.36 Titrant 9243 Input: glass weighing boat20 mL 9241 and Stir time: 300 s20 mL formamide Titration temperature: 50°C

Dough 0.2 6 20.9 2.8 Titrant 9258 Heat with drying oven DO302,40 mL methanol 190°C, 200 mL N2/min

Stir time: 900 s

Zwieback 0.5 6 1.89 0.59 Titrant 9258 Crush sample with mixer40 mL methanol Heat with drying oven DO302,

120°C, 200 mL N2/minStir time: 900 s

Biscuit 0.4 6 5.79 0.87 Titrant 9243 Crush sample with mixer20 mL LM 9241 Input: glass weighing boat20 mL formamide Stir time: 900 s

Titration temperature: 45°C

Corn flakes 0.5 6 6.14 0.69 Titrant 9258 Crush sample with mixer40 mL methanol Heat with drying oven DO302,


Noodles 0.4 6 10.1 1.3 Titrant 9258 Crush sample with mixer40 mL methanol Heat with drying oven DO302,


Instant 0.15 6 8.58 0.3 Titrant U 9233 Crush sample with mixerpotato flakes 40 mL LM 9241 External extraction: 2 g in

70 g formamide; 1 h at 25°CInput: 5 mL aliquot with syringe

Potato chips 0.3 6 4.83 0.72 Titrant 9243 Crush sample with mixer20 mL LM 9241 Input: weighing boat20 mL formamide Stir time: 900 s

Titration temperature: 50°C

Reagents:Titrant 9243 two-component reagent (titrant) 5 mg H2O/mL MERCK No. 9243Titrant 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

B) Coulometric determination using DL37These products are not well suited for the coulometric method (water content too high, solubility toopoor).



The direct titration at 50°C using formamide gives reproducible results. A furtherpossibility is an external extraction with methanol at room temperature.

The water content determination using drying oven DO302 at 190°C gaveconsistently reproducible results. At even higher temperatures (220°C) a slowdecomposition of the dough was observed (product turned dark brown toblack). The "water content" increased, and the post-consumption was high.

Using drying oven DO302 at 120°C for the water content determionation of tehfinely crushed sample gave consistently reproducible results. At higher tempe-ratures (140°C) the Zwieback™ begins to decompose slowly, resulting in adark brown coloration of teh product and in considerably falsified results. Afterfinely crushing the sample, it can also be titrated directly at 50°C in thepresence of formamide or as external extarction with 100 mL methanol at 50°Cfor 60 minutes in the sonicator.

Directly titrating this product in the presence of formamide at 45°C givesreproducible results. External extarction with methanol is a further possibility.As this product contains sugars which decompose at elevated temperatures,drying oven DO302 can not be used for this determination.

In spite of the fine milling of the sample, the presence of formamide, elevatedtemperatures and the longer stir time, water is not released compeltely from thisproduct.Using a direct titration in methanol/formamide 1:1 at 50°C with a titration timeof 1 hour, the water content was found to be only 5.9% .The water content determination using drying oven DO302 at 140°C gaveconsistently reproducible results.

The sample is crushed finely in the mixer. The determination using drying ovenDO302 at 140°C generates reproducible results. A direct titration at 50°C inthe presence of formamide can also be used.

In spite of crushing the sample, adding formamide and raising the temperature,the titration took ver 40 minutesmination in the drying oven with a maximumtemperature of 130°C is possible; the titration takes approx. 10 minutes, themean value of 3 samples was 8.2% (RSD= 10.6%). At higher temperaturesthe product begins to decompose. Highly reproducible results can be obtainedwith an external extraction with formamide for 1 hour at ambient temperature.Do not heat, as this will cause the flakes to swell and teh extraction liquid willthicken drastically.

The finely ground sample can be titrated directly at 50°C after addingformamide. For the external extarction method, chloroform must be present inthe solvent mixture due to the fat conetnt of the chips.

All-purpose flour

Biscuit

Corn flakes

Noodles

Instant potato flakes

Potato chips

Doug

Zwieback™


Karl Fischer TitrationWater Content Determination of Zwieback™

A. Aichert, Application Laboratory, Nov. 1990

Sample: 0.5 g Zwieback™

Preparation:Crush sample in a mixer. Heat samplein the crucible in the flue of the dryxingoven DO302, evaporate the moistureand transfer the vapor into the titrationcell by dry pruge gas.Oven temperature: 120°CPurge gas: 200 mL nitrogen/min

Sample Input:Fill sample from weighing boat throu-gh NS14 neek into the crucible.

Titrant:KF Titrant 5 mg H2O/mL(MERCK No. 9258)

Solvent:40 mL Methanol

Remarks:Stir time: 900 sThe time required for the evaporationof the water is preferably entered as stirtime.At higher temperature (from 140°C)starts a slow decomposition (the colorof sample changes to dark brown orblack)

Application:Quality control pastry producer

Instruments:METTLER DL35 KF Karl Fischer TitratorElectrode DM142Drying oven DO302Dot matrix printer Epson LX-800

Method:

Results und Statistics:


5. Spices and Dehydrated Products

Most spices release water very slowly.

Therefore, formamide must be added to these products and the temperatureelevated for a direct titration. External extarction using methanol or formamidehas been shown to give good results. Extra care must be taken to grind andtherefore these products have to be homogenized thoroughly.

Water is enclosed in cellular structures in vegetable based dehydrated foods.The water is released slowly and incompletely. For thsi reason it is necessaryto chop these foods finely and use the external extarction with methanol orformamide at temperatures up to 50°C.

Caution: Foods containing carbohydrates may thermally decompose in aprocess that generates water at elevated temperatures.

In general

References Radar, B.R.,"Determination of Moisture in Dried Vegetables",J. Assoc. Off. Anal. Chem. 50, 701-703 (1967).

Thung, S.B.,"Comparative Moisture Determaintion in Dried Vegetables by Drying afterLyophilisation or the Karl Fischer Method"J. Sci. Food Agric. 15, 236-244 (1964).

Scholz, E.,"Wasserbestimmung in Lebensmitteln",Deut. Lebensmittel Rundschau 79, 302-306 (1983)


Applications: Spices and Dehydrated Foods



Ground pepper 0.03 6 10.7 0.92 Composite 5 External extraction: 0.5 g in30 mL methanol 55 mL formamide; 1 h at 25°C

Input: 3 mL aliquot with syringe

Ground curry 0.07 6 7.59 0.21 Titrant 5 External extraction: 2 g in30 mL Solvent 50 mL formamide; 1h at 25°C


Sea salt 1.5 7 0.0332 6.7 Composite 2 Grind sample in mortaradherent water 10 mL methanol Input: weighing boat

20 mL chloroform Stir time: 250 s

Mixed spice 0.2 5 1.83 0.49 Composite 2 External extraction: 5 g in40 mL methanol 45 g methanol; 45 min at 25°C


Spiced sauce 0.03 6 59.2 0.49 Composite 5 Input: syringe with needle40 mL solvent Stir time: 10 s

Soy sauce 0.5 6 63.4 0.41 Composite 5 Input: syringe with needle40 mL methanol Stir time: none

Mustard 0.02 6 72.4 0.59 Titrant 5 External extraction: 1.2 g in30 mL solvent 60 mL formamide/decanol 1:1


Ketchup 0.06 6 63.7 0.29 Titrant 5 Homogenize with mixer30 mL Solvent Input: syringe without needle

Stir time: 300 s

Chives 0.1 7 8.6 4.8 Titrant 5 External extraction: 3.2 g indehydrated 30 mL Solvent 60 g formamide; Crush 20 s with

high-speed mixer; 30 min at 60°CInput: 2 mL aliquot with syringe

Instant coffee 0.015 7 6.2 0.62 Titrant 5 External extraction: 0.5 g in30 mL Solvent 50 mL formamide; 10 min at 25°C

Input: 1 mL aliquot with syringeReagents:Titrant 5: One-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. 34805 (titrant)Composite 5: One-component reagent HYDRANAL® Composite 2 Riedel No. 34806 (titrant)



Table salt 1.0 5 359.6 4.2 100 mL Coulomat A Heat with drying oven DO337, 300°C5 mL Coulomat C 200 mL air/min, Titration time: 600 s

Titration parameters:Adjustment: control gain = 5, Titration duration time: 600 s; Automatic drift determination; Manual titration start



Remarks on the Applications

Ground pepperand groud curry

These sample release water slowly. They can be titrated directly by addingformamide and raising the temperature.The most reproducible results, however, can be obtained by external extractionwith formamide.

No problems are encountered when these samples are titrted directly.A coulometric determination can be performed using the drying oven.

Mixed spices are slightly hygroscopic.When titrating directly, a sluggish endpoint is observed(approx. titration time: 20 min, water content: 3-4%).The drying oven cannot be used for the determination, as the sample starts todecompose at 130°C.Only the external extraction with methanol gives reproducible results.

A simple direct titration.Renew the solvent after 3 samples.

Homogenize sample well.The sample does not dissolve completely even after the addition of chloroform.Titrating the sample directly is thus not an effective method (sluggish endpoint,subsequent consumption). The titration time is approximately 15-20 min withRSD = 1.1% for 7 samples.External extraction of the mustard using formamide /1-decanol 1:1 mixturegives consistently reproducible results.

The thoroughly homogenized sample can be titrated directly without encoun-tering problems.

This product is crushed for 20 s in a high-speed hand mixer in formamide priorextraction during 30 min at 60°C.The thick suspension is filled into the back side of a 10 mL plastic syringe.Widening the syringe outlet to 3 mm allows the suspension to be measuredmore easily. To prevent moisture uptake from the ambient, the opening issealed with a stopper after input.A further set of measurements (3 samples) resulted in a mean value of 8.7%(RSD = 2.2%).

Due to a sluggish endpoint, a direct titration of the coffe is not a suitable method.The finely pulverized sample is completely dissolved in pure formamide afterstirring for 5-10 minutes at 25°C.

Sea saltand table salt

Mixed spices

Spiced sauceand soy sauce

Mustard

Ketchup

Dehydrated chives

Instant coffee


Karl Fischer TitrationWater Content Determination of Spices

Sample: 0.07 g Ground Curry

Preparation:Extract 2 g finest ground curry during 1hour at room temperature in 50 mLformamide.Let undissolved solids settle. Pipet 2mL of the supernatant solution andtitrate.Determine the blank value of the ex-traction solvent and enter as BLANK in[µg water].

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

Titrant:KF titrant, 5 mg H2O/mL(HYDRANAL® Titrant 5 No. 34801)

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

Remarks:METTLER Method KF49.The sample weight is only asked afterthe titration (method parameter D: 1).Back weighing is easily performed.


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

Dr. R. von Rotz, Application Laboratory, Dec. 1990

Results und Statistics:


6. Various Foodstuffs

References Zürcher, K. and Hadorn, H.,"Wasserbestimmung nach Karl Fischer an verschiedenen Lebensmitteln",Deut. Lebensmittel Rundschau 77, 343-355 (1981).

Scholz, E."Wasserbestimmung in Lebensmitteln"Deut. Lebensmittel Rundschau 79, 302-306 (1983).

In general Water content determinations of vegetable-based products are often difficult,as the water is frequently contained in cellular structures from which it isreleased slowly and incompletely.

The method of choice, therefore, is titration at elevated temperatures up to50°C, adding formamide to the sample if necessary. External extarction of thesamples using methanol at 50-60°C is also recommended. A method that hasproven useful in a number of cases is the direct titration in boiling methanol.

Crushing the samples thoroughly is a must in all cases.

Meat products can be titrated at room temperature in methanol after they havebeen shredded well. For fatty samples the addition of chloroform is recommen-ded.

Shredded meat products can also be dissolved in the solvent mixture 1-decanol/formamide/methanol 8:2:1 . This mixture can be used effectively foran external extraction.


Applications: Other Foodstuffs



Ground 0.4 6 4.84 1.2 Titrant No. 9243 Crush with mixerhazelnuts 20 mL LM 9241 Input: weighing boat

20 mL formamide Stir time: 900 sTitration temperature: 50°C

Cocoa powder 0.2 6 5.68 0.74 Titrant No. 9243 External extraction: 3 g in30 mL LM 9241 50 mL formamide; 30 min at 25°C


Black tea 0.2 6 7.42 0.26 Titrant No. 9258 External extraction: 6 g in30 mL methanol 60 mL formamide; 45 min at 50°C


Ground 0.2 6 2.65 0.28 Titrant No. 9243 External extraction: 5 g incoffee beans 30 mL LM 9241 50 mL methanol; 30 min at 50°C


Tobacco 0.15 6 8.65 0.20 Composite 5 External extraction: 3 g in30 mL methanol 100 mL methanol; 60 min at 25°C


Liver sausage 0.03 6 61.6 0.29 Titrant 5 External extraction: 3 g in 60 mL30 mL Solvent 1-decanol/formamide/methanol 8:2:1

1 hour at 25°CInput: 1 mL aliquot with syringeStir time: 60 s

Chicken broth 0.3 5 4.89 0.16 Titrant 5 External extraction: 3 g in 60 mL30 mL Solvent 1-decanol/formamide/methanol 8:2:1

1 h at 25°CInput: 6 mL aliquot with syringeStir time: 60 s

Instant pudding 1.5 6 2.24 0.94 Titrant No. 9243 Input: weighing boat30 mL LM 9241 Stir time: 60 s

Titrtaion temperature: 50°C

Chocolate 0.15 5 3.22 1.0 Titrant U 9233 Input: weighing boatflavour 20 mL LM 9241 Stir time: 300 s

20 mL formamide Titration temperature: 30-35°C

Reagents:Titrant 5: Two-component reagent HYDRANAL® Titrant 5 Riedel No. 34801 (titrant)Solvent: Two-component reagent HYDRANAL® Solvent Riedel No. 34800 (solvent)Composite 5: One-component reagent HYDRANAL® Composite 5 Riedel No. 34806 (titrant)Titrant 9243: Two-component reagent (titrant) 5 mg H2O/mL MERCK No. 9243Titrant 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

B) Coulometric determination using DL37The coulometric method is not applicable for these products (high water content, poor solubility).


Remarks on the Applications

Hazelnuts The results obtained by titrating directly in the presence of formamide with a15 minutes stir time are easily reproducible. After 2 samples the solvent mustbe replaced as the extraction becomes les efficient (lower values, increasedsubsequent consumption).

In spite of the addiction of formamide and the higher temperature, the directtitration takes over 40 minutes. The sample can be dissolved completely atroom temperature in pure formamide.

External extraction with formamide gives highly reproducible results. Adetermination using the drying oven should be undertaken at temperatures notexceeding 130°C. More than 15 minutes drying time are required. At highertemperatures, the product decomposes slowly.

The ground coffee release water slowly. For this reason the external extractionwith methanol at 50-60°C is used, a method which generates reproducibleresults. Direct titration in boiling methanol may also be used.

Direct titration shows a sluggish endpoint, even after stirring for 10 minutes.The repeatability RSD is 0.7% (n=3) compared to 0.2% (n=6) fo the externalextraction with methanol.

Titration in the presence of formamide results in a sluggish endpoint in spite of10 minutes stir time (incomplete water release). This gives results which arebadly reproducible and water content values which are too low (x=60.6%,n=4, RSD=1.5%).The solvent mixture 1-decanol/formamide/methanol 8:2:1 dissolves thesample to completion (decanol for fats, formamide for proteins and methanolas the solvating agent).This solvent mixture is used for to solve the sample. The solution is biphasicand must be stirred vigorously when removing the sample aliquots.

External extraction using the solvent mixture 1-decanol/fromamide/methanol8:2:1 leads to easily reproducible and reliable results.

Direct titration at 50°C using the normal KF solvent gives good, reproducibleresults with a stir time of 10 minutes, even though the sample is not dissolvedcompletely (n=6, RSD=0.94%). The total titration time is approx. 12-15 min.Upon the addition of formamide, the sample dissolves completely, the watercontent values obtained, however, are not different. Direct titration of thepowder at ambient temperature, on the other hand, clearly results in lessreproducible values (n=6, RSD=6.2%). The titration time is 16-20 minutes.

The sample is completely dissolved after adding formamide and stirring at 30-35°C for 5 minutes. A slow side reaction takes place, as can be seen by theincreased drift value (the drift increases by 10-15 µg H2O/min after eachsample). To minimize this error, use the smallest possible sample size, renewthe solvent after two samples, and maintain the temperature less than 35°C.At higher temperatures, the side reaction increases rapidly.

Cocoa powder

Black tea

Coffee beans

Tobacco

Liver sausage

Instant pudding

Chicken broth

Chocolate flavour


7. Beverages and Drink Concentrates

In general Fruit juices and alcoholic beverages allow their water contents to be determinedwithout problems.Lemonades may also contain carbonates or bicarbonates which react with KFreagents, thereby generating water. This leads to artificially elevated watercontents. Determinations using the drying oven may be performed providedthat the sample is thermally stable. Thesamples however, frequently containsugars which decompose in reactions that release water at temperatures aboveabout 50°C.

Zürcher, K., and Hadorn, H."Wasserbestimmung nach Karl Fischer an verschiedenen Lebensmitteln"Deut. Lebensmittel Rundschau 77, 343-355 (1981).

Scholz., E."Wasserbestimmung in Lebensmitteln"Deut. Lebensmittel Rundschau 79, 302-306 (1983).

These can be titrated directly without encountering any problems.Caution: The dissolving capacity of the solvent will be exhausted after fewsamples.

The reproducibility of the direct titration can be improved significantly bydegasing the sample in the sonicator for approx. 15 minutes.

The fibres in the juice may stop th esyringe. Thesample input will then no longerbe representative (filter effect).

These powders are hygroscopic. The water content cannot be determined withthe drying oven as the powders contain sugars and thus are not thermallystable. Adding formamide to the solvent increases the reproducibility of thedirect titration (for example: from RSD=2.5% to 0.4% for n=6 samples).

References

Comments on the applications

Cognac, egg liquor,orange juice,

black currant syrup

Beer

Tomato juice

Powders forisotonic drinks and

instant ice tea


Applications: Beverages and Drink Concentrates



Cognac 0.03 6 60.7 0.19 Titrant U 9233 Input: syringe with needle30 mL LM 9241 Stir time: none

Beer 0.02 6 91.1 0.45 Titrant U 9233 Sonicate sample30 mL LM K 9221 Input: syringe with needle

Stir time: none

Wine 0.03 7 87.0 0.18 Titrant 60626 Input: syringe with needle30 mL LM 60625 Stir time: none

Egg liquor 0.04 7 54.7 0.29 Titrant 60626 Input: syringe with needle30 mL LM 60625 Stir time: none

Orange juice 0.03 6 88.7 0.27 Titrant U 9233 Input: syringe with needle30 mL LM 9241 Stir time: none

Tomato juice 0.02 6 91.7 0.22 Titrant U 9233 Sonicate to homogenize30 mL methanol Input: syringe with needle

Stir time: none

Black currant 0.05 6 30.8 0.24 Titrant 60626 Input: syringe with needleSyrup 30 mL LM 60625 Stir time: none

Instant 1.0 5 0.581 2.3 Titrant 60626 Input: weighing boatice tea 20 mL LM 60625 Stir time: 300 s

20 mL formamide

Isotonic drink 0.3 6 1.24 0.49 Titrant U 9233 Input: weighing boatpowder 20 mL LM 9241 Stir time: 300 s

20 mL formamide

Reagents:Titrant U 9233: Two-component reagent (Titrant U) 5 mg H2O/mL MERCK No. 9233LM 9241: Two-component reagent (Solvent) MERCK No. 9241Titrant 60626: Two-component reagent (Titrant) Fluka No. 60626LM 60625 Two-component reagent (Solvent) Fluka No. 60625

B) Coulometric determination using DL37The coulometric method is generally not applicable for these products (water content too high).


8. Cosmetics

In general Water or alcohol based cosmetics such as shampoo, liquid soaps, sun lotions,toothpaste, after-shave, perfume, or nail polish can be titrated easily using thestandard KF solvents.Products containing fats (hand lotion, day cream, lipstick) and etheral oils aretitrated by adding chloroform or 1-decanol. In certain cases elevated tempe-ratures (50°C) are required.

Exchange the solvent after three samples, as the dissolving capacity will beexhausted. Air bubbles in the syringe can influence the results.

Renew the solvent after five samples, as th edissolving capacity will beexhausted. 1-decanol or other special solvents (MERCK) that dissolve fats andoils can be used instead of chloroform.

Since this product does not dissolve completely even in th epresence ofchloroform, direct titration is not a suitable method (slow and incomplete waterrelease, long titration times).The sample can be dissolved in 1-decanol at 50°C in the sonicator.

1-decanol is used in place of chloroform. The solvent must be replaced aftersix samples, as its dissolving capacity will be exhausted.The water content of this sample can also be determined coulometrically. Thereproducibilty is clearly better.

The sample must be homogenized thoroughly. Direct titration is not as wellsuited for this sample , as it does not dissolve completely.

Comments on the applications

Shampoo

Creams

Lipstick

Massage oil

Toothpaste


Applications: Cosmetics



Shampoo 0.03 7 80.3 0.29 Composite 5 Input: syringe with needle30 mL methanol Stir time: 60 s

After-shave 0.3 6 32.7 0.39 Composite 5 Input: syringe with needle30 mL methanol Stir time: 30 s

Day cream 0.015 6 80.5 0.46 Composite 5 Input: syringe with needle15 mL methanol Stir time: 60 s15 mL chloroform

Sun lotion 0.02 7 71.5 0.54 Composite 5 Input: syringe with needle20 mL methanol Stir time: 60 s10 mL chloroform

Lipstick 0.1 6 2.13 0.85 Titrant U 9233 External dissolution: 1.8 g in30 mL LM 9241 50 mL 1-decanol;

30 min at 50°C in sonicatorInput: 2 mL aliquot with syringeStir time: none

Massage oil A 2.0 6 0.0461 0.31 Titrant U 9233 Input: syringe with needle20 mL LM 9241 Stir time: none20 mL 1-decanol

Toothpaste 0.02 6 40.5 0.24 Composite 5 External extraction: 2 g in30 mL methanol 50 mL methanol;

30 min at 25°CInput: 0.5 mL aliquot with syringeStir time: 60 s

Reagents:Titrant U 9233: Two-component reagent (Titrant U) 5 mg H2O/mL MERCK No. 9233LM 9241: Two-component reagent (Solvent) MERCK No. 9241Composite 5: One-component reagent HYDRANAL® Composite 5 5 mg H2O/mL Riedel-de Haën No. 34805



Massage oil B 0.3 6 0.1059 0.21 100 mL Coulomat A Input : syringe with needle5 mL Coulomat C Stir/titration time: 60 s

Titration parameters:Adjustment: control gain = 5, End level: 0.1 µg H2O/s (0.1 µg H2O/s over drift)Automatic drift determination; automatic titration start

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


9. 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 • 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


10. 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


11. 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.

This application bulletin represents selected, possible application examples. These have been tested with all possible carein our lab with the analytical instrument mentioned in the bulletin. The experiments were conducted and the resulting dataevaluated based on our current state of knowledge.

However, the application bulletin does not absolve you from personally testing its suitability for your intended methods,instruments and purposes. As the use and transfer of an application example are beyond our control, we cannot acceptresponsibility therefore.When chemicals and solvents are used, the general safety rules and the directions of the producer must be observed.

Mettler-Toledo GmbHAnalyticalCH-8603 Schwerzenbach, SchweizTelefon (01) 806 77 11, Fax (01) 806 73 50Internet: http://www.mt.com

Subject to technical changes© 09/04 Mettler-Toledo GmbH, ME-00724478Printed in Switzerland on 100% chlorine-free paper,for the sake of our environment.

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