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Determination of the composition of pyrolytic oilby liquid chromatographic methods of analysisJerome SandersAtlanta University

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Recommended CitationSanders, Jerome, "Determination of the composition of pyrolytic oil by liquid chromatographic methods of analysis" (1979). ETDCollection for AUC Robert W. Woodruff Library. Paper 2105.

DETERMINATION OF THE COMPOSITION OF PYROLYTIC OIL

BY LIQUID CHROMATOGRAPHIC METHODS OF ANALYSIS

A THESIS

SUBMITTED TO THE FACULTY OF ATLANTA UNIVERSITY

IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR

THE DEGREE OF MASTER OF SCIENCE

BY

JEROME SANDERS

DEPARTMENT OF CHEMISTRY

ATLANTA, GEORGIA

MAY 1979

<V

ABSTRACT

CHEMISTRY

SANDERS, JEROME B.S., TUSKEGEE INSTITUTE, 1976

DETERMINATION OF THE COMPOSITION OF PYROLYTIC OIL

BY LIQUID CHROMATOGRAPHIC METHODS OF ANALYSIS

Advisor: Professor Malcolm B. Polk

Thesis dated May 1979

The various components of the pyrolytic oil were

determined by liquid chromatography using a bonded phase

CH-10 column. Component identification was conducted at

wavelengths of 280 and 240 nm. Chromatographic analyses

of the pyrolytic oil at a wavelength of 200 nir and analyses

using paired-ion reagents were performed without component

identification.

ACKNOWLEDGEMENTS

I would like to express my grateful appreciation to

Dr. Malcolm B. Polk for his planning and guidance of this

research.

I am also indebted to Mr. Metha Phingbodhipakkiya for

his unending assistance on instrumentation.

An overwhelming thanks goes to my mother, Mrs. Susie

S. Hudson, and to my father from whom all my inspiration

comes.

111

TABLE OF CONTENTS

Page

ACKNOWLEDGEMENTS iii

LIST OF TABLES v

LIST OF FIGURES vi

INTRODUCTION 1

EXPERIMENTAL 8

RESULTS AND DISCUSSION 19

CONCLUSION 31

REFERENCES 32

IV

LIST OF TABLES

Table Page

1 Compounds Used in the Analysis of

Pyrolytic Oil at 280 and 240 ran 11

2 Compounds Used in the Analysis of

Pyrolytic Oil at 240 nm . 15

3 Compounds Used in the Analysis of

Pyrolytic Oil at 200 nm . .". 17

4 Liquid Chromatographic Peak

Enhancement Results at 280 nm 20

5 Liquid Chromatographic Peak

Enhancement Results at 240 nm 22

v

LIST OF FIGURES

Figure Page

1 Liquid Chromatogram of

Pyrolytic Oil at 280 nm . 12

2 Liquid Chromatogram of

Pyrolytic Oil at 240 nm 13

3 Liquid Chromatogram of

Pyrolytic Oil at 200 nm 30

VI

INTRODUCTION

Liquid chromatography is a form of chromatography that

separates the components of a substance by the distribution

of the substance between two phases, a mobile phase and a

stationary phase, with the mobile phase being a liquid. A

typical high performance liquid chromatography system con

sists of: high pressure pumps that maintain the mobile

phase supply, a column packed with stationary phase, an

injection system by which the sample or solute can be injected

onto the column, a detector to monitor the column eluates and

a recorder to record the response of the detector.

In high performance liquid chromatography (HPLC) the

mobile phase is pumped through the column under high pressure

at a controlled rate, the solute is injected onto or as close

as possible to the head of the column which is composed of

the stationary phase. Separation of the solute occurs as it

passes through the stationary phase in the mobile phase.

The column eluates are passed through the detector and the

responses of the detector is recorded in the form of a

chromatogram.

HPLC is now being used on a wide scale for the separa

tion of various substances ranging from aromatic amines to

long chain fatty acids. The forms of HPLC used to accomplish

separation of substances vary but the chroir.atograph.ic

1

2

procedure remains the same. Sophisticated HPLC systems can

be equipped to produce separation using any form of liquid

chromatography. The forms mainly used are as follows: gel

permeation, ion exchange, liquid-liquid, liquid-solid and

bonded phase chromatography.

The various forms of liquid chromatography differ mainly

in the composition of the stationary phase in the column and

the mobile phase used in accomplishing separation.

In gel permeation, the column is packed with microporous

particles that achieve separation according to the sizes of

the molecules. Large molecules are excluded from the pores of

the packing while smaller molecules may permeate the pores

partially or totally depending upon their size. Large

molecules are eluted from the column first and smaller mole

cules are eluted last. Gel permeation is not generally

classed as a chromatographic procedure because separation is

achieved by molecular size rather than on the basis of mole

cular interaction but gel permeation can be carried out using

a liquid chromatography system. In ion exchange the

stationary phase consists of ion exchange resin beads or

pellicular particles. Ion exchange chromatography is widely

used in the analysis of amino acids, drugs, metabolites,

pharmaceutical products, inorganic salts, and generally for

compounds containing ionized or ionizable groups. In liquid-

liquid chromatography, the mobile phase is liquid and the

3

stationary phase is a liquid supported on a solid. The

supporting solid may be either a completely porous material

such as a wide pore silica gel or porous glass, or a

superficially porous (pellicular) material. Liquid-liquid

chromatography has been used in the preparation of organic

and inorganic substances and many substances of biological

origin, including fatty acids. Liquid-solid chromatography

has been used for some time, employing adsorbents such as

silica gel and alumina as stationary phases in the separation

of amino acids, polynuclear hydrocarbons, and a wide range of

both high molecular weight substances and substances of high

polarity. The mobile phase can be either a nonpolar or

polar organic solvent. Bonded phase chromatography combines

the properties of a liquid-solid system and a liquid-liquid

system. The development of bonded phase chromatography

stemmed from the difficulties encountered in maintaining a

liquid stationary phase on the solid support in a liquid-

liquid system. These difficulties led to the production of

a column packed with substances chemically bonded to the

surface of suitable solid supports, a bonded phase. The

substances bonded to the solid supports exhibited the proper

ties of a liquid phase making the bonded phase a hybrid

1 between a solid and a liquid.

Vast improvements have been made in the equipment for

liquid chromatography systems. There are two major types of

solvent pumps used in HPLC--the mechanical or syringe pump

4

and the reciprocating pump. The methods of detection mainly

used are refractive index and ultraviolet (uv) absorption.

Refractive index detectors measure the bulk property of the

column eluates and uv absorption detectors detect any samples

which absorb in the uv region of the electromagnetic spectrum.

Some liquid chromatography systems can be equipped with a

solvent programmer that allows gradient elution. Gradient

elution is the controlled change of the composition of the

mobile phase during elution of solute through the column.

With the development of liquid chromatography a large

number of organic compounds that were insufficiently volatile

or too unstable to be separated by gas chromatography could

then be analyzed. Another advantage is the wide choice of

detectors available for use in liquid chromatography systems.

Also, reverse-phase and normal phase chromatography can be

performed using liquid chromatography systems. Reverse-phase

chromatography is the separation of the components of a mix

ture using a nonpolar stationary phase and a polar mobile

phase. Normal phase chromatography is the separation of the

components of a mixture using a polar stationary phase and a

nonpolar mobile phase. Therefore, polar and nonpolar sub

stances can be separated using a liquid chromatography system.

Gas chromatography is limited in its application to polar

substances. When polar substances are distributed between the

gas mobile phase and the solid stationary phase of gas

chromatography, the forces between the solute and stationary

5

phase are high, which results in long retention times.

Sample recovery in liquid chromatography can be accomplished

more easily than in gas chromatography. Thermally unstable

compounds which may not be analyzed using gas chromatography

are suitable subjects for liquid chromatography.

The applicability of HPLC systems can be seen in a re

cent work describing a relatively new form of HPLC in which

3ion-pairing reagents are added to the mobile phase. This

form of HPLC is called paired-ion chromatography. In paired-

ion chromatography, the ion-pairing reagents form a reversible

ion-pair complex with the ionized solute. Reversed-phase,

high pressure liquid chromatography has been successfully

applied to the analysis of peptides and proteins by the

addition of hydrophilic (for example, phosphoric acid) or

hydrophobic (for example, hexanesulfonic acid) ion-pairing

reagents, or both, to the mobile phase. On a reversed-phase

chromatographic support, increased polarity due to the forma

tion of hydrophilic ion-paired complexes results in a

decreased retention time for the material and a sharpening

3

of peaks.

Pyrolytic oils are viscuous, brown liquids obtained

from the pyrolysis of solid waste. Pyrolysis is the heating

of material in limited amounts of oxygen. With the continuing

search for energy alternatives, pyrolysis appears to be a

remarkable process that produces valuable fuels. A number of

companies have developed and marketed processes by which such

fuels may be obtained. A few cities in the United States

have installed or are considering development of pyrolysis

plants using these processes as a method of generating

commercial fuels. One city that has installed a company-

designed pyrolysis plant is Baltimore. The plant was

scaled to pyrolyze 1000 tons per day of raw refuse, with

the resulting gases being burned to produce steam. The

city of Seattle is considering a pyrolysis process designed

to generate an ammonia gas for use in chemical feedstock.

San Diego is the site of a recovery plant for a flash pyro

lysis process that uses recycled hot char to heat organic

materials. The products are then used to heat the reaction

to produce an oil fuel product. The single most important

product of the system is the pyrolytic oil - comparable to

No. 6 fuel oil.

The composition of products that result from pyrolysis

depends on the composition of the solid wastes, and the tem

perature, pressure, and residence time of pyrolysis. The

products obtained from the pyrolysis of municipal solid

wastes are noncondensable gases, a liquid, and a solid resi

due. The liquid is the pyrolytic oil which contains a

mixture of neutral compounds, strong and weak acids, and

water.

Many investigators have determined the products of the

pyrolysis and distillation of wood. Some of the products

identified are: naphthalene; dimethylnaphthalene;

7

2,3-dimethylanthracene; 2-methoxy-4-methylphenol; guaiacol;

2-methoxy-4-ethylphenol; 2-methoxy-4-propylphenol; phenol;

cresols; xylenols; pyrocatechol; 4-methylpyrocatechol;

dimethylpyrogallol; 4-hydroxy-3-inethoxytoluene; 4-hydroxy-

3-methoxystyrene; eugenol; cis-isoeugenol; trans-isoeugenol;

vanillin; acetovanillone; pyrogallol; 1,3-dimethylether;

4-hydroxy-3,5-dimethyltoluene; 4-hydroxy-3-methoxystyrene;

4-hydroxy-3-methoxy-l-vinylbenzene; benzene; sinasaldehyde ;

coniferaldehyde; syringaldehyde; allylsyringol; methyl-

naphthalene; p_-ethylphenol; 2 ,4, 6-trimethylphenol; a_-naphthol;

p_-hydroxybenzaldehyde; p_-hydroxyacetophenone ; acetosyringone ;

butyrolactone; crotonic acid; maltol; 2-hydroxy-3-methyl-

5-2-cyclopentenone; 2,6-dimethoxyphenol; tiglaldehyde;

methyl isopropyl ketone; methyl ethyl ketone; methyl furyl

ketone; acetaldehyde; furan; 2,3-butandione; methylfuran;

l-hydroxy-2-propanone; glyoxal; acetic acid; furfural;

acetone; propionaldehyde; methanol; 3-hydroxy-2-butanone;

ethanol; diacetyl; furfuryl alcohol; formaldehyde; 1-butanol;

isobutyl alcohol; anthracene; and phenanthrene.

The work described in this thesis was conducted on

samples of pyrolytic oil produced from the pyrolysis of

sawmill wastes. The purpose of the work was to identify

the compounds contained in the samples of pyrolytic oil by

liquid chromatographic methods of analysis.

EXPERIMENTAL

Instrumentation.--A Varian Aerograph Model 8500 Liquid

Chromatograph equipped with two high pressure syringe pumps

was used for these experimental studies. Each pump was

individually maintained within a cabinet housing; each

housing containing a solvent reservoir, a flow controller,

and a pressure monitor. Enclosed in one pump housing was

the solvent programmer (pump A), which contains the controls

for gradient elution, and a mixing chamber. The other pump

was labeled pump B. The injector used for this system was

a Varian Aerograph Loop Injector. A double beam, vis/uv

Varichrom Liquid ChromatograDhy Detector with a standard

wavelength range of 200-720nm was used. The maximum

absorbance range was 0.005 A (full scale) with a minimum, of

2.0 A (full scale). The bandwidth setting for these experi

mental studies was 8 nm. A Varian Model A-25 Strip-Chart

Dual Channel Recorder equipped with crossover pens was used

to record data. The span setting was 0.1 mv with a chart

speed of 0.50 in/min.

Preparation of Degassed Water.--Each day the water to

be used as a solvent in the liquid chromatograph (LC) had to

be degassed. In the degassing procedure the water was heated

at 110° for 35 min. It was then stirred under suction for 20

min, followed by filtering to make it ready for use in the LC,

For the experimental studies at 280 nm, HPLC 2-propanol

8

9

and acetonitrile, from Fisher Scientific, were used. The

remaining experimental studies were performed with Burdick

& Jackson Spectragrade 2-propanol and acetonitrile.

Liquid Chromatography of the Pyrolytic Oil at 280 nm.--

The pyrolytic oil was prepared for injection by column

chromatography. Liquid chromatography was conducted on a

pre-prepared sample of the combined column cuts 1-22 unless

otherwise stated.

Reverse-phase gradient elution was started at 1007o

water (Solvent A), and continued to 100% of a 50/50 mixture

of 2-propanol-acetonitrile (Solvent B). A four step series

constituted the gradient elution solvent program, with solvent

B being increased at rates of k°L B/min for 5 min, 5% B/min

for 10 min, 3% B/min for 10 min, and finally decreased at a

rate of 10% B/min for 10 min for regeneration. A 0.25 in

(o.d.) by 25 cm Varian Aerograph MicroPak bonded phase CH-10

column was used. The following instrumental conditions were

set: flow rate=2 ml/min; wavelength for the uv detector=280

nm; and absorbance range=0.1 A. These instrumental condi

tions were unchanged throughout the chromatographic studies

at 280 nm.

A 4-yl sample of the pyrolytic oil was injected onto

the column using a 10-pl Glenco syringe. The chromatogram

obtained is referred to as a reference chromatogram for the

enhancement studies at 280 nm.

A select few of the compounds suspected to be present, in

10

the pyrolytic oil were chromatographed at 280 nm. Chroma-

tograms were obtained after the injection of varying amounts

of a sample of the pyrolytic oil plus one of the suspected

compounds. The components were identified by noting the

enhancement of peaks which correspond to the component in

the reference chromatogram. Table 1 contains the compounds

analyzed (see Fig. 1 for reference chromatogram). The

chromatographic samples were prepared by the addition of

1-yl of suspected compound to 2 ml of pyrolytic oil.

Liquid Chromatography of the Pyrolytic Oil at 240 nm.--

Reverse-phase gradient elution was started at 100% water and

continued to 80% of a 50/50 mixture of 2-propanol-acetonitrile.

A three step series constituted the gradient elution solvent

program, with solvent B being increased at rates of 67o B/min

for 5 min, 57O B/min for 10 min, and finally decreased at a

rate of 10% B/min for 10 min for regeneration. The following

instrumental conditions were set: flow rate=2.3 ml/min;

wavelength=240 nm; and absorbance range=0.1 A.

A number of the compounds suspected to be contained in

the pyrolytic oil were chromatographed at 240 nm using the

same chromatographic sample preparation as at 280 nm. Table

1 also lists the compounds analyzed at 240 nm (see Fig. 2

for reference chromatogram).

For further chromatographic studies at 240 nm , the

sensitivity was decreased to 0.5 A and the flow rate was

decreased to 2 ml/min. The solvent program remained the

11

Table 1. Compounds Used in the Analysis of Pyrolytic Oil

at 280 and 240 ran.

Compounds used at 280 nm Compounds used at 240 nm

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

11.

12.

13.

14.

15.

16.

17.

18.

19.

20.

21.

22.

23.

24.

25.

26.

Hydroquinone

Furfural

2-Methoxy-4-methylphenol

Phenol

4-Allylanisole

p_-Me thoxypheno 1

5-Methylfurfural

Anethole

Guaiacol

1,2-Dimethoxy-4-

propenylbenzene

m-Methoxyphenol

1-Allylnaphthalene

o-Cresol

p_-Cresol

m-Cresol

1-Methylnaphthalene

Veratrole

2-Methylnaphthalene

m-Dimethoxybenzene

Eugenol

Isoeugenol

2,3-Dimethylnaphthalene

2-Methoxy-4-propylphenol

p_-Dime thylnaphthalene

1,5-Dimethylnaphthalene

Naphthalene

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

11.

12.

13.

14.

15.

16.

17.

18.

19.

20.

21.

22.

23.

24.

25.

26.

27.

28.

29.

1-Methylnaphthalene

1,5-Dimethylnaphthalene

Veratrole

Hydroquinone

4-Allylanisole

2,3-Dimethylnaphthalene

Anethole

2-Methylnaphthalene

2-Methoxy-4-propylphenol

m-Methoxyphenol

Furfural

Isoeugenol

Guaiacol

Phenol

Eugenol

2-Methoxy-4-methylphenol

m-Cresol

o-Cresol

p_-Cresol

Acetovanillone

2,4-Dihydroxyacetophenone

p_-Dimethoxybenzene

1-Allylnaphthalene

m-Dimethoxybenzene

2,4-Dimethylacetophenone

Naphthalene

3,4-Dimethoxystyrene

2,5-Dihydroxyacetophenone

p_-Methoxyphenol

ECo00

CM■P

•H

Oo

•H4-1

OP-l

oIU'MO4-J

So43a'

•r-l

13

CN)

BcoCNO

•r-l

ouoBdO4JmEo

o•Hcr

•H

14

same. An 8-yl sample of pyrolytic oil was injected onto

the column. The solvent program was allowed to continue

to completion. The sample size was increased to 9-ul and a

chromatogram of the column eluates was obtained. Table 2

contains the compounds reanalyzed at 240 ran.

Liquid Chromatography of Pyrolytic Oil at 240 nm

Using a NH2-10 Column.--A 0.25 cm (o.d.) by 25 cm Varian

Aerograph bonded phase NI^-IO column was used for these

chromatographic analyses. Reverse-phase gradient elution

was started at 100% water and continued to 100% acetonitrile.

The solvent program used was the same as for the chromato

graphic studies at 240 nm using the CH-10 column.

Liquid Chromatography of Pyrolytic Oil Using a Vydac-

AX Column.--A 0.25 cm (o.d.) by 50.cm Varian Aerograph ion-

exchange anionic Vydac-AX column was used. The following

instrumental conditions were set: flow rate=1.5 ml/min;

wavelength=254 nm; and absorbance range=0.5 A. The reverse-

phase gradient elution program remained the same as it was

for the previous chromatographic studies performed at 240 nm.

Reverse-phase gradient elution was started at 100% 0.015M

ammonium acetate and continued to 807o 6M ammonium acetate .

The 0.015M ammonium acetate solution was prepared by

dissolving 1.15 g of ammonium acetate in 1000 ml of degassed

water. To this solution, 6M acetic acid was added dropwise

until the solution attained a pH of 4.4. The solution was

then filtered. The 6M ammonium acetate solution was prepared

15

Table 2. Compounds Used in the Analysis of Pyrolytic

Oil at 240 nm.*

Compounds reanalyzed at 240 nm

1. Eugenol

2. 2-Methylnaphthalene

3. 1-Allylnaphthalene

4. Guaiacol

5. Acetovannilone

*The flow rate was 2 ml/min and the absorbance rangewas 0.5 A.

16

by dissolving 231.24 g of ammonium acetate in 500 ml of

degassed water. To this solution 6M acetic acid was

added dropwise until the solution attained a pH of 4.4.

The solution was then filtered.

In Procedure 1, the standard solvent program was used.

In Procedure 2, the solvent program consisted of two steps.

In the initial step solvent B (6M ammonium acetate) was

increased at a rate of 2% B/min for 25 min, which resulted

in a total of 50% solvent B. In the following step solvent

B was decreased at a rate of 10% B/min for 5 min. The flow

rate was decreased to 1 ml/min. In Procedure 3, the solvent

program consisted of a three step series, with solvent B

being increased at rates of 2% B/min for 10 min, then at a

rate of 67O B/min for 10 min. These two steps gave a total of

80%,of solvent B. In the final step, solvent B was decreased

at a rate of 10% B/min for 10 min.

Liquid Chromatographv of Pyrolytic Oil at 200 nm.--A

0.25 in (o.d.) by 25 cm Varian Aerograph MicroPak bonded

phase CH-10 column was used. Reverse-phase gradient elution

was started at 100%, water, and continued to 80%, acetonitrile.

A three step solvent program was used. First solvent B was

increased at a rate of 6%, B/min for 5 min and then increased

at a rate of 5% B/min for 10 min. In step three solvent B

was decreased at a rate of 10% B/min for 10 min. The

following instrumental conditions were set: flow rate=0.5 A.

Table 3 contains the compounds analyzed at 200 nm.

17

Table 3. Compounds Used in the Analysis of Pyrolytic Oil

at 200 ran.

Compounds used at 200 ran

1. Eugenol

2. Guaiacol

3. 1-Butanol

4. Butyric Acid

Paired-Ion Chromatography of Pyrolytic Oil at 280 nm.--

A 0.25 in (o.d.) by 2 mm (i.d.) by 4 cm Varian Aerograph Guard

Column designed for the Varian 8500 Liquid Chromatograph was

used in these chromatographic studies. The guard column was

packed with microparticulate packing using the dry-pack-tap-

fill method. The guard column was installed between the high

pressure injector and the 0.25 in (o.d.) by 2 mm (i.d.) by

25 cm Varian Aerograph MicroPak bonded phase MCH-10 column

which is used for paired-ion chromatography.

Sample Preparation.--The pyrolytic oil samples were pre

pared from a stock sample of pyrolytic oil received from the

Georgia Institute of Technology on July 14, 1978. Tetrahydro-

furan was used to dilute 10 ml of the stock sample to 175 ml.

This solution was filtered, then vacuum filtered through a

0.45-micron filter.

Paired-Ion Chromatography (PIC) Reagent B-5 (Waters

18

Associates) was used for the preparation of paired-ion

solvents. Solvent A was prepared by the addition of one

bottle (18.4 ml) of PIC Reagent B-5 to 1000 ml of degassed

water. The solution was stirred for 5 min, then vacuum

filtered through a 0.45-micron filter. Solvent B was

prepared by the addition of one bottle (18.4 ml) of PIC

Reagent B-5 to 1000 ml of a 50/50 mixture of 2-propanol-

acetonitrile. The solution was stirred for 5 min, then

vacuum filtered through a 0.45-micron filter.

Reverse-phase gradient elution was started at 100%

solvent A and continued to 100%, solvent B. A four step

series constituted the gradient elution solvent program,

with solvent B being increased at rates of 4% B/min for 5

min, 6% B/min for 10 min, 3% B/min for 10 min, and finally

decreased at a rate of 10% B/min for 10 min. The following

instrumental conditions were set: flow rate=2 ml/min;

wavelength=280 nm; and absorbance range=0.5 A.

A 3-pl sample of pyrolytic oil was injected onto the

column. The solvent program continued to completion, and a

chromatogram of the column eluates was obtained. A new four

step solvent program was then introduced to the solvent pro

grammer. In this program, solvent B was increased at rates

of 2% B/min for 10 min, 2% B/min for 25 min, 3% B/min for

10 min, and finally decreased at a rate of 10% B/min for 10

min. A 3-pl sample of pyrolytic oil was injected onto the

column. The solvent program continued to completion and a

chromatogram of the column eluates was obtained.

RESULTS AND DISCUSSION

Data obtained from the liquid chromatograph were in the

form of a chromatogram which is an analog curve relating the

concentration of solute in the column eluates with respect

to time. The column eluates of 4-yl of pyrolytic oil pro

duced the chromatogram that is shown in Fig. 1 containing

25 peaks that were numbered for identification by enhancement

of peak absorbance. Peak identification by enhancement of

peak absorbance was achieved by adding varying amounts of a

known compound to the chromatographic sample of pyrolytic

oil. All of the compounds shown in Table 1 were identified

by enhancement of peak absorbance. Although the chromato-

grams produced at 280 nm exhibited low resolution, identifi

cation by this method was effective. The initial chromato-

grams produced by unspiked samples of pyrolytic oil were

used as references in the identification of peaks. The

results of peak identification of the pyrolytic oil at 280 nm

are shown in Table 4.

The position in the chromatogram at which the components

in Table 4 showed absorbance was determined by the percent of

solvent B at which these components were eluted from the

column. The more polar components were eluted from the

column in the mobile phase that contained a low percent of

solvent B and the less polar components were eluted as the

percent of solvent B in the mobile phase increased.

19

20

Table 4. Liquid Chromatographic Peak Enhancement Result

at 280 nm.

Peak Number Component Identified

2 Hydroquinone

3 Furfural

4 Phenol

5 p-Methoxyphenol and

5-Methylfurfural

6 Guaiacol

7 m-Methoxyphenol

9 o_-Cresol

10 p_-Cresol

11 m-Cresol

12 Veratrole

14 m-Dimethoxybenzene and

Eugenol

15 Isoeugenol

16 1,2-Dimethoxy-4-propenylbenzene

and 2-Methoxy-4-propenylphenol

17 4-Allylanisole and Anethole

18 p_-Dimethoxybenzene

19 Naphthalene

20 2-Methylnaphthalene and

1-Allylnaphthalene and

1-Methylnaphthaiene

21 2,3-Dimethylnaphthalene and

1,5-Dimethylnaphthalene

21

The increase in the percent of solvent B was shown on

the chromatogram of YL increment in accordance with the

solvent program set for solvent B during the operation of

reverse-phase gradient elution. The graph of solvent B

started at the top left corner of the chromatogram and

continued on a stepwise slope to the lower right corner,

making it possible to identify peaks in the enhancement

studies by coinciding percents of solvent B.

Chromatographic analyses at 240 nm using the CH-10

column produced chromatograms containing 30 peaks with

better resolution and lower peak absorbance than the

chromatograms at 280 nm. Peak identifications at 240 nm

with the CH-10 column were made by peak enhancement studies

as before. The chromatogram of the pyrolytic oil at 240 nm

is shown in Fig. 2. The results of peak identifications at

240 nm are presented in Table 5.

The components contained in Table 2 were chromatographed

again to confirm their previous peak assignments. The changes

in peak assignments that occurred were acknowledged in Table

5. There were a few minor discrepancies in the peak

identifications at 240 and 280 nm and two major discrepancies.

Of the latter, one was in the identification of p_-dimethoxy-

benzene as peak number 12 at 240 nm and peak number 18 at

280 nm. The other occurred when m-dimethoxybenzene was

determined not to be a component of the pyrolytic oil at

240 nm; it was identified as peak number 14 at 280 nm.

22

Table 5. Liquid Chromatographic Peak Enhancement Results

at 240 nm.

Peak Number Component Identified

2 Hydroquinone

3 Furfural

4 Phenol

5 p_-Methoxyphenol

6 Guaiacol and Acetovanillone

7 2,4-Dihydroxyacetophenone

and m-Methoxyphenol

8 o_-Cresol, p_-Cresol and

m-Cresol

9 2-Methoxy-4-methylphenol

10 Veratrole and

2,5-Dihydroxyacetophenone

12 p_-Dimethoxybenzene

13 Eugenol

14 Isoeugenol and

2,4-Dimethylacetophenone

15 2-Methoxy-4-propylphenol

17 Naphthalene

19 4-Allylanisole and Anethole

20 2-Methylnaphthalene

21 3,4-Dimethoxystyrene and

1-Methylnaphthalene

22 1-Allylnaphthalene

23 2,3-Dimethylnaphthalene

and 1,5-Dimethylnaphthalene

23

With the identification of most of the peaks contained in

the chromatograms of the pyrolytic oil at 280 and 240 ran,

the trend of the column eluates can be seen. The more polar

components were weakly retained on the column and thus were

eluted from the column faster than the less polar components

which were strongly retained on the column. In Scheme 1 the

structures of the components identified at 280 and 240 nm

are presented in the order of elution.

Chromatographic analyses using the NFU-IO and Vydac-AX

columns were unsuccessful. The stationary phases in these

columns were not optimum for separation of the pyrolytic oil.

The chromatograms of the pyrolytic oil at 254 nm using the

anion-exchange Vydac-AX column showed very low resolution.

The paired-ion chromatography of the pyrolytic oil con

ducted at 280 nm using the MCH-10 column produced good

chromatograms with moderate resolution and a marked decrease

in the retention times of component peaks. Unsuccessful

attempts were made to improve the resolution in the chromato

grams by decreasing the rate of introduction of solvent B in

the solvent program, but no -improvements occurred. The

chromatograms produced with paired-ion reagents (pentane

sulfonic acid) were among the better chromatograms obtained

of the pyrolytic oil, but reproducibility of the chromato

grams could not be maintained with the instrumental conditions.

Therefore, enhancement studies were not conducted.

Component

Hydroquinone

24

Scheme 1

Structure

OH

Furfural

Phenol

CHO

OH

p_-Me thoxyphenol

Guaiacol

Acetovanillone

OH

CH3

OH

OCH,

COCH3

OCH,

OH

25

Scheme 1 (Continued)

Component Structure

OH

m-Methoxyphenol

2,4-Dihydroxyacetophenone

o-Cresol

COCH3

.OH

OH

CH3

H

p_-Cresol

CH-

m-Cresol

OH

OH

2-Methoxy-4-methylphenol

'OCH-

CH-

26

Scheme 1 (Continued)

Component

Veratrole

Structure

OCHo

-OCH3

2,5-Dihydroxyacetophenone

HO'

COCH3

Y0H

p_-Dimethoxybenzene

5-Methylfurfural

OCH.

OCH3

m-Dimethoxybenzene

QCH-

Eugenol

CH^CH—CHa

OCH-

OH

27

Scheme 1 (Continued)

Component

Isoeugenol

2,4-Dimethylacetophenone

Structure

CH=CH-CH,

OCH,

OH

COCH.

CH3

H3

2-Methoxy-4-propylphenol

OH

r OCH.

Naphthalene

4-Allylanisole

OCH,

-CH—

OCH

Anethole

H=CH-CH.

28

Scheme 1 (Continued)

Component Structure

2-Methylnaphthalene

CH.

3,4-Dimethoxystyrene

1-Methylnaphthalene

CH=CH-

OCH,

OCR,

:h

1-Allylnaphthalene

o-CH—CHo

2,3-Dimethylnaphthalene

H3C.

CH.

1,5-Dimethylnaphthalene

29

The chromatograms of the pyrolytic oil produced at 200 nm

using the CH-10 column showed better resolution than the pre

vious chromatograms obtained at 280 and 240 nm using this

column. A chromatogram of the pyrolytic oil obtained at

200 nm is shown in Fig. 3. The component peaks of high

absorbance were well resolved but the component peaks of

low absorbance were difficult to distinguish from noise.

Peak identifications of the pyrolytic oil could not be

determined at 200 nm due to the indistinguishability of

component peaks of low absorbance from noise. The enhance

ment studies at 200 nm were discontinued.

Fig. 3. Liquid Chromatogram of Pyrolytic Oil at 200 nm.

CONCLUSION

Analysis of the data o^ained of the pyrolytic oil by

liquid chromatography suggests that for further chromato-

graphic studies the paired-ion reagents should be used at

a wavelength of 200 run, These chromatographic studies

should be conducted on an HPLC system that will not produce

a high level of noise at a wavelength of 200 nm.

31

REFERENCES

1. J. N. Done, "Applications of High-Speed Liquid

Chromatography," J. Wiley and Sons, New York,

N. Y., 1974, pp. 5-6.

2. R. P. W. Scott, "Contemporary Liquid Chromatography,"

Techniques of Chemistry, Vol. XI, J. Wiley and Sons,

New York, N. Y., 1976, pp. 8-9.

3. W. S. Hancock, and M. T. W. Hearn, Science, 200,

1168 (1978). =

4. "Pyrolysis--A True Alternative for Solid Waste

Disposal," Am. City & County, 9_2, 81 (1977).

5. M. B. Polk, "Development of Methods for the

Stabilization of Pyrolytic Oils," Annual Report,

USEPA/Grant R-804444020, pp. 1-2, Atlanta University,

Atlanta, Georgia, October^1978.

32