GEOLOGICAL SURVEY CIRCULAR 848-C 

Organic Substances in Water 

Organic Substances in Water 

Edited by Phillip E. Greeson 

Briefing Papers on Water Quality 

GEOLOGICAL SURVEY CIRCULAR 848-C 

1981 
United States Department of the Interior 

JAMES G. WAIT, Secretary 

Geological Survey 

Doyle G. Frederick, Acting Director 

Library of Congress catalog-card No. 81-607886 

Free on application to Distribution Branch, Text Products Section, 

U. S. Geological Survey, 604 South Pickett Street, Alexandria, VA 22304 
FOREWORD 

In August 1974, the Water Resources Division of the U.S. Geological Survey introduced the first 

of a series of briefing papers that were designed to increase the understanding of its employees of the 

significance of various aspects of water quality. Numerous briefing papers have been prepared by the 

Quality of Water Branch. Others will be prepared as the need arises. Each paper addresses a 

separate topic and is written in a nontechnical, easy-to-understand manner for distribution within the 

organization. 

Because of the favorable reception that the papers have received and their apparent effectiveness in accomplishing the objective stated above, it would appear that their wider distribution 

would serve a useful purpose. It is hoped that a wide range of persons, including those interested in 

the quality of our Nation's water resources, but who have little or no technical training, will find value 

in reading the papers. Furthermore, it is hoped that the papers will be suitable for supplemental 

reading in secondary education programs and in beginning college-level courses. 

The U.S. Geological Survey plans to publish several U.S. Geological Survey Circulars that contain compilations of briefing papers on particular aspects of water quality. This third Circular contains three papers describing selected topics on organic substances in water. 

Philip Cohen 

Chief Hydrologist 

III 

CONTENTS 

Page 

Foreword__________________________________________________________________ III 

Abstract___________________________________________________________________ C1 

Why study organic substances in water?, by Ranard J. Pickering--------------------- 3 

Taste and odor in water, by Robert A. Baker ------------------------------------- 5 

Classification and fractionation of organic solutes in natural waters, 

by Jerry A. Leenheer ----------------------------------------------------- 11 

ILLUSTRATIONS 

Page 

FIGURE 1. Solubility classification of organic compounds--------------------------- C12 

2. Proposed classification scheme for organic solute characterization__________ 14 

3. Fractionation-analysis flow chart for dissolved organic carbon------------- 16 

TABLES 

Page 

TABLE 1. DOC fractionation analysis of Wyoming ground-water samples------------- C18 

2. DOC fractionation analysis and selenium fractionation analysis of 

Colorado ground-water samples ----------------------------------- 18 

v 

BRIEFING PAPERS ON WATER QUALITY 

Organic Substances in Water 

Edited by Phillip E. Greeson 

ABSTRACT 

This is the third of several compilations of briefing papers on 

water quality by the U.S. Geological Survey. Each briefing 

paper is prepared in a simple, nontechnical, easy-to-understand 

Cl 

manner. This U.S.- Geological Survey Circular contains papers 

on selected organic substances in water. Briefing papers are included on "Why study organic substances in water?," "Taste and 

odor in water," and "Classification and fractionation of organic 

solutes in natural waters." 

Why Study Organic Substances in Water? 

By Ranard J. Pickering 

ABSTRACT 

Organic substances are found virtually everywhere in our environment, and their importance in water-quality studies is being realized rapidly. Not only do naturally occurring organic 

compounds present problems in water utilization, but the 

myriad of manmade organic compounds have been shown to 

have many detrimental effects. Because of the tremendous 

number of these compounds, their identification and quantification is complex and expensive. 

INTRODUCTION 

Organic substances are those substances containing compounds of carbon and hydrogen; that 

is, hydrocarbons or compounds derived from them. 

At one time, it was believed that hydrocarbons 

could be formed only by living organisms-thus, 

the term "organic." Now, however, man has 

learned not only to produce many of these natural 

compounds synthetically but has created 

thoasands of new organic compounds in his quest 

for a better life. 

The presence of organic materials in our enviro~­

ment is so extensive that it could be said that we 

live in an organic world. The food we eat, the 

clothes we wear, the homes in which we live all 

contain large amounts of organic substances. 

Everyone is aware of the tremendous increase in 

the use of plastics within the past few years, and 

the more recent trend toward production of 

biodegradable organic consumer products. The 

degradation of such materials, along with the 

disposal of wastes from their manufacture, constitute an ever-increasing source of organic contamination to our environment. On the other hand, 

there are manufactured organic substances that do 

not degrade, and the persistence of some of these 

compounds has caused great concern among environmentalists. 

IMPORTANCE OF ORGANIC SUBSTANCES 

Organic substances are important in waterquality studies for many reasons. The bacterial oxC3 

idation of organic carbon from natural sources and 

from municipal, industrial, and agricultural wastes 

is a major factor leading to depletion of oxygen in 

many streams. Nutrients in organic substances can 

impart color and odor to water, and can act as carriers of trace metals and other elements by combining with them chemically or inducing their sorption 

by suspended sediment. 

Every day we are adding to the list of manmade 

organic compounds that are suspected of having 

detrimental effects on the environment-either 

aesthetic or toxic. A few years ago, industry initiated an expensive change in formulation of 

detergents to reduce the unwanted persistence of 

their foaming properties. An ever-increasing 

number of pesticides have been banned or severely 

limited in application because of their documented 

or suspected adverse effects on valuable living 

things- both plant and animal; these effects vary 

from reduction of the probability of survival of 

newly hatched fish to causing cancer or birth 

defects in humans. There has been a recent suggestion that some of the substances considered most 

dangerous to man may be produced from harmless 

organic compounds by the very processes which we 

use in our water treatment plants to make the 

water safe for human consumption. 

MEASUREMENT OF ORGANIC SUBSTANCES 

Measurement of the unending variety of organic 

substances can be at many different levels of 

detail, ranging from the most gross measure, 

organic carbon, to determination of a specific 

organic compound or organometallic complex. 

These measurements can be either qualitative 

identifications or quantitative determinations. 

They may be for the purpose of establishing 

natural background levels of organic substances, 

or for regulatory detective work, such as identification of the source of polluting crude oil by its 

relative content of simple organic components. 
Instrumentation for identification and quantification of organic substances is becoming more and 

more complex and expensive. Positive identification of a specific compound commonly requires a 

series of satisfactory comparisons with standards, 

using a different identification principle for each 

comparison, followed by a mass spectrogram for 

confirmation based on the way in which the compound breaks apart. 

Questions about the effects on man or other 

forms of life of many of the organic substances 

present in our ground and surface waters will remain unanswered for many years. There is no good 

way to measure the chronic effect on man of longterm exposure to low concentrations of organic 

0 substances, except by waiting for that long term to 

pass. Even then, probably only a statistical inference can be drawn- one which will be un-

. provable to anyone who does not want to believe it. 

CONCLUSION 

The more information that we have on the occurrence and behavior of the wide variety of organic 

substances in water, the better will be the basis for 

the inferences that we must draw. When we conclude that a particular organic compound or group 

represents a hazard (or a benefit), we will have at 

least a limited basis for deciding on an appropriate 

course of action. 

C4 
Taste and Odor in Water 

By Robert A. Baker 

ABSTRACT 

The cause of the taste and odor of water is the organic 

substances content. These substance·s often occur at concentrations of a single microgram per liter or less. The sources of the 

substances are varied; they may be either naturally occurring, 

or from the introduction of manmade materials into waterways. 

INTRODUCTION 

One may ask why briefing papers intended to 

describe organic sustances and their effects on the 

environment should include a discussion of taste 

and odor. Nature has endowed most persons with a 

sensory system much more responsive than many 

advanced instrumental devices. The senses of odor 

and taste are olfactory (smell) and gustatory (taste) 

responses. 

Judgment about water supplies is foremost a 

sensory evaluation. Clarity, sparkle, freedom of 

color, and absence of objectionable taste and odor 

are desired properties. Except for certain 

sulfurous or highly mineralized waters, the cause 

of taste and odor of water is the organic substances 

content. The organic constituents that cause taste, 

odor, color, and toxicity are often at concentrations of micrograms per liter (p. g/L) or less. It is 

this ability to sense very low levels of contaminants 

that has afforded protection to man during evolutionary time. Surveillance is required, if water 

resources are to be protected and consumers are to 

be provided a high quality supply. 

Sensory impairment from water has been chiefly 

a surface-water problem; ground water has been 

less affected. Adsorption processes in soils and 

rock usually remove dissolved and particulate 

organics. Humic components and other naturally 

occurring organics always have been present in 

surface water. Decomposition of vegetative matter 

is the principal source. However, man has complicated the situation. Not only has he released 

quantities of municipal and industrial wastewaters 

with concomitant organic pollution, but many of 

C5 

the organics are not biodegradable. Such 

biodegradably resistant organics are termed 

"refractory." They can originate from landfill 

leachates, agricultural runoff, and manufacturing 

wastes. 

Waste-treatment technology has accelerated and 

not improved on natural processes for organic 

reduction. Even the best of treatment plants 

release refractory organics. As water reuse intensifies, because of population and industrial growth, 

so does the risk of exposure to refractory 

materials. In turn, refractory buildup requires 

more advanced wa.Ste-treatment processes. 

Water-treatment plants generally can cope with 

low levels of organic wastes. They fail when slug 

discharges or organics are involved. Even the best 

of today's ·plants has limited analytical capability 

for providing early warning of slugs of organic constituents. By the time routine procedures identify a 

problem, there are already sources of consumer 

complaints in the distribution system. Seasonal 

and climatic factors also are involved. During low 

flow and decreased dilution, constituents normally 

present in water are more concentrated. Heavy 

rainfall or other runoff results in flushouts. 

Flushout dilution is offset by scour of decaying 

vegetative matter in benthic (bottom) layers. The 

associated organic materials often impose a severe 

taste and odor impact. 

In the vernacular of the water technology, "taste 

and odor" are inseparable. Separation of the effect 

of odor from taste is impossible. There are four 

basic tastes: salty, sweet, sour, and bitter. 

Characterization of taste (flavor) by food 

technologists has been more successful than have 

attempts at characterization of odor. Flavor is the 

sum of taste and odor sensations. Odor 

characterization schemes have been proposed, but 

none has proven suitable for field use. Individuals 

engaged in related research often have problems 

describing odor character and communicating a 

precise description. 
SUBJECTIVE PROPERTIES 

Properties such as taste, odor, and appearance 

are evaluated by humans. These subjective or sensory judgments are made by procedures termed 

organoleptic testing. In order to understand the 

meaning of taste and odor measurement results, it 

is necessary to understand individual differences in 

acuity, to know the test conditions, and to specify 

the analytical conditions. 

Persons differ in their response to selected 

stimuli (odor), not only in level of concentration but 

in characteristics. Thus, selection of a panel for 

taste and odor testing requires individual "calibration." Training often enhances an individual's sensory ability. Age, smoking and eating habits, state 

of health, and other factors can influence sensory 

capability. 

A basic question the tester must ask concerns 

the intended use of sensory results. If the objective 

is to judge the response of the population as a 

whole, then the panel should be representative of 

the general public. However, if the threshold concentration that will minimize complaints is desired, 

then the most sensitive segment of the population 

should be tested. It is not unusual for there to be a 

10,000-fold range in threshold odor concentratio.n 

as measured by individuals. For example, phenohc 

odor thresholds have been measured from 0.016 to 

16.7 mg/L. 

In research, large numbers of panelists can be 

justified. However, many small waterplants and 

field crews must make measurements with only 

limited staff. At least two persons should be involved in any taste and odor measurement: one to 

prepare the sample and one to make the measurement. Their roles can be switched to give a second 

result. The results may differ considerably and still 

be correct because of the ·aforementioned individual variation in response. This interaction between panelist and odor type is the most important 

consideration in determining panel constitution 

and size. A small carefully selected panel can 

predict effectively the response of the populationas-a-whole. The appended references discuss these 

factors. 

OLFACTION 

The physiology and theory of olfaction are subjects of extensive study and debate. Agreement is 

far from complete, but certain facts are established. There must be a molecular diffusion process 

that carries the odorant to the reception site of the 

organ. Volatility and solution in the sensory surC6 

face with transmission of a signal to the brain constitute the dynamic physiological process. All the 

odor stimuli do not affect the same olfactory cells. 

The odorant must "fit." Thus, the probability of impaction on the proper reception s!te is enhanced ~y 

the concentration and length of time the odorant 1s 

present. The olfactory membranes have a high surface to mass ratio and under normal circumstances 

they do a yeoman task. However, the senses can 

suffer fatigue. Fatigue, as defined in this discussion, is of a chemical nature as opposed to physical 

fatigue. It has been shown that presence of 

background odor, odor type, person involved, and 

the interaction of these effects influence the acuity 

of human response to odor. 

There a_re practical considerations involved in 

providing the proper conditions and controls on 

sensory testing. These, too, will be reviewed. Suffice it to say that the number of sensory judgments 

that an individual can make over a given time will 

depend on these complex interrelated factors. Certain chemicals, such as formaldehyde and 

hydrogen sulfide, paralyze the olfactory nerves. 

Once this happens, the subject is unaware of higher 

concentrations. It is the reason operators entering 

sumps, chemical tanks, excavations, sewers, and 

so on, must follow safety procedures. They can be 

overcome before they realize their danger. In 

measuring threshold odors (air or water media), 

stimuli may alter reponse- perhaps significantly. 

Although water-quality rationale presumes that 

any perceptible taste or odor is undesirable, this is 

not entirely valid. Persons adapt to the quality of 

their water supply. Often travelers cannot abide 

the taste and odor of supplies that are perfectly acceptable to local populations. The taste of distilled 

water or beverages prepared with distilled water is 

considered "flat" by most persons. These observations involve the concentration of stimuli (organic 

or inorganic) at or near threshold level. Greater 

concentrations are termed suprathreshold. 

Because of the emphasis on reducing taste and 

odor of water, most knowledge in the waterrelated field is at the threshold level. 

Suprathreshold sensory evaluation has not been investigated as intensely. 

SAMPLING 

Odor measurements ideally are made on freshly 

obtained samples. These should be taken in glassstoppered bottles that are completely filled.· 

Storage should be avoided, prior to sensory 

testing. If this is not possible, refrigeration is 

essential; it slows the natural biological processes 
that alter the trace organic composition. Chemical 

and physical processes also are involved. If sensory 

measurements are made on stored samples, the 

results should note this fact- including the duration and conditions of storage. Sample 

temperature at the time of collection should be 

recorded. Samples that are at a temperature exceeding that specified for the sensory test should 

be cooled to the proper level. 

ODOR MEASUREMENTS 

Measurements are made to determine intensity 

and to characterize (describe) odor. The principle 

of the measurement is relatively simple. The water 

sample is diluted with odor-free water until the 

least definitely perceptible odor is obtained. Increasing concentrations of odorant are tested 

beginning with levels below the threshold. Odor is 

reported as threshold odor number, TON, or as 

odor intensity index, On. These terms are related: 

TON =2°II. 

The On is the number of times the concentration 

of the original sample is halved by addition of odorfree water to obtain the least definitely perceptible 

odor. The index is most convenient with industrial 

wastewaters. An On of 18 immediately imparts an 

impression of the strength based on the halving of 

the orginal sample 18 times. The equivalent TON is 

262,000. The TON is the greatest dilution of the 

sample with odor-free water to yield the least 

definitely perceptible odor. A treatment-plant rawwater supply with a TON of 8 would have an on of 

3. Note that when the TON= 1, the On=O. 

The aforementioned methods of testing for odor 

describe precise controls for assuring odor-free 

glassware, odor-free dilution water, sample 

temperature, and environmental and operating 

conditions. It is imperative that the precautions 

and controls be observed, if meaningful results are 

to be obtained. 

Research has established a basis for these controls. Ideally, the test area should be temperatureand humidity-controlled, and the air free of 

background odor. If the samples are colored, the 

testers will be biased in selecting the flask containing the sample from those containing only odorfree water. This problem can be eliminated by using opaque glassware for the samples or by 

monochromatic lighting that masks the sample 

color. Color is a factor in perception of taste. Food 

technologists have documented many instances 

when an individual attributed widely varying 

flavors to the same substance (such as ice cream) 

when taste-and-odor-free coloring was added. 

However, if the individual is blindfolded or 

monochromatic lighting hides the color change, 

consistent and objective judgments are made. 

Samples containing turbidity should be handled in 

the same manner as colored samples to preclude 

bias. 

Odor tests are made in covered 500-mL, 

widemouth Erlenmeyer flasks containing 200 mL 

of solution. The solution may be entirely sample or 

some dilution of sample. The odor-free dilution 

water is prepared by passing the best available 

reagent-grade water, often freshly distilled, 

through a fresh activated-carbon column. The carbon is contained in an all-glass system. However, 

the carbon surface can serve as a host for algae or 

other organisms which produce odorous 

metabolites. Therefore, the condition of the carbon 

and the quality of the odor-free water must be 

monitored carefully. 

The specification that sensory measurements be 

made in an odor-free environment is based on experimental experience. The senses are affected by 

background odor. Similar background odors inhibit 

threshold measurements. Dissimilar odors enhance 

threshold detection. This was demonstrated in 

studies using n-butural and m-cresol. The former 

has a pleasant, sweet odor at low concentration. 

The latter has a "fence post," noxious odor. Unfortunately, field tests are seldom made without some 

background odor. Most water treatment plants are 

not equipped with an odor-free laboratory. The 

odor of chlorine and related compounds prevails. 

Every effort should be made to conduct sensory 

tests in areas of minimum background odor. 

Temperature is a factor in olfaction. The reason 

is volatility. As temperature increases, volatility is 

enhanced. Odor threshold measurements usually 

are made at 40°C (near body temperature) or 

60°C. Research has shown that for selected stimuli 

in aqueous solution, the TON will not differ 

significantly over a range of 20° to 60°C. 

However, these were precisely controlled tests 

(Baker, 1963), under ideal laboratory conditions. 

The panelists in the controlled tests noted that at 

60°C, a temperature preferred by water utilities 

because of hot-water domestic implications, the 

odorant was readily lost and repeat tests required 

fresh samples. A "steaming" effect on the olfactory 

system was described. At 20°C, the samples were 

"dead." The 40°C temperature was preferred. 

Details of the odor-threshold testing procedure will 

not be given. These are described in American 

C7 
Society for Testing and Materials (1979) and 

American Public Health Association and others 

(1976). 

STANDARDS 

Quantitative odor standards can be of two kinds. 

A limit can be set on odor of the water as a whole, 

or the concentrations of individual substances can 

be regulated. The concentrations of substances are 

specified in terms of a ratio between allowable concentration and the threshold odor or taste concentration. Such standards are difficult to administer. 

The great variation in sensory response by individuals raises the question of the choice of 

regulatory limit. However, there is another factor. 

Many times the sensory causing substances combine in a nonadditive manner. 

Two odorants mixed in aqueous solution may 

create (1) additivity, the resulting odor is the sum 

of the individual odors, (2) synergism or intensification, the odor produced exceeds that 

predicted by simple addition, or (3) antagonism or 

suppression, the odor produced is less than that 

predicted by simple addition. These effects are 

described by Rosen and others (1962) and Baker 

(1963). Synergism is the effect experienced most 

often and it has practical implications. If an industrial or municipal waste effluent of acceptable 

threshold is discharged to a receiving body with no 

appreciable odor, synergism could produce a water 

of unacceptable odor or synergism could produce a 

water of unacceptable quality. Obviously, standards based on single components or even the 

waters treated as seperate entities would fail. 

European communities have set recommended 

taste and odor numbers for surface water supplies 

at values of 3 to 20. This variation is caused by 

their definition of classes of water use, ranging 

from the cleanest to the most polluted class. The 

World Health Organization states in its 1971 International Standards for drinking water that there 

should not be objectionable taste and odor in 

water. The Commission of European Communities 

has issued a proposed directive stating that a TON 

of zero is recommended with a maximum TON of 2 

at 12°C or 3 at 25°C for drinking water. It is interesting that Russian standards for organic 

substances in raw waters to be used as domestic 

(drinking) supplies are based solely on taste or odor 

threshold concentrations. Generally, sensory 

threshold values are well below toxicologically 

dangerous levels. For most of the many organic 

C8 

substances in water, there is no toxicological information, particularly for defining risk from chronic 

exposure to low concentrations. 

SELECTED REFERENCES 

American Public Health Association, American Water 

Works Association, Water Pollution Control Federation, 

1976, Standard methods for the examination of water and 

wastewater, 14th edition: New York, American Public 

Health Association, 1193 p. 

American Society for Testing and Materials, 1979, Annual 

book of standards, Part 31: Philadelphia, American Society 

for Testing and Materials, 1280 p. 

Baker, R. A., 1963, Critical evaluation of olfactory 

measurement: Journal of the Water Pollution Control 

Federation, v. 35, p. 582-591. 

Baker, R. A., 1963, Odor effects of aqueous mixtures of organic 

chemicals: Journal of the Water Pollution Control 

Federation, v. 35, p. 728-741. 

Baker, R. A., 1963, Odor testing laboratory: Journal of 

the Water Pollution Control Federation, v. 35, p. 

1396-1402. 

Baker, R. A., 1963, Threshold odors of organic chemicals: 

Journal of the American Water Works Association, v. 55, p. 

913-916. 

Baker, R. A., 1968, Limitation of present objective techniques 

in sensory characterization, correlation of subjective 

methods in the study of odors and taste: American Society 

for Testing and Materials, Special Technical Publication 

440, p. 87-107. 

Bruvold, W. H., 1968, Scales for rating the taste of water: 

Journal of Applied Psychology, v. 52, p. 245. 

Dougherty, J. D., and Morris, R. 1., 1967, Studies on the 

removal of Actinomycetes musty taste and odors in water 

supplies: Journal of the American Water Works 

Association, v. 59, p. 1320-1326. 

Ettinger, M. B., and Ruckhoft, C. C., 1951, Effect of stepwise 

chlorination on taste and odor producing intensity of some 

phenolic compounds: Journal of the American Water Works 

Association, v. 43, p. 561-567. 

Gerber, N. N., and Lechavalier, H. A., 1965, Geosmin, an 

earthy-smelling substance isolated from Actinomycetes: 

Applied Microbiology, v. 13, p. 935. 

Hoak, R. D., 1960, Discussion-Evaluating the taste and odor 

control problem: Journal of the American Water Works 

Association,. v. 52, p. 517-519. 

Jenkins, D., Medsker, L. L., and Thomas, J. F., 1967, Odorous 

compounds in natural waters, some sulfer compounds 

associated with blue-green algae: Environmental Science 

and Technology, v. 1, p. 731-735. 

Maloney, T. E., 1963, Research on algal odor: Journal of the 

American Water Works Association, v. 55, p. 481-486. 

Medsker, L. L., Jenkins, D., and Thomas, J. F., 1968, Odorous 

compounds in natural water.Anearthy-smelling compound 

associated with blue-green algae and Actinomycetes: 

Environmental Science and Technology, v. 2, p. 461-464. 

Middleton, F. M., Braus, H., and Ruckholft, C. C., 1952, 

Fundamental studies of taste in water supplies: Journal of 

the American Water Works Association, v. 44, p. 538-546. 

Middleton, F. M., Grant, W., and Rosen, A. A., 1956, Drinking 

water taste and odor: Industrial and Engineering 

Chemistry, v. 48, p. 268-274. 
Ogata, M., and Miyake, Y., 1973, Identification of substance in 

petroleum causing objectionable odor in fish: Water 

Research, v. 7, p. 1493-1504. 

Popalisky, J. R., and Pogge, F. W., 1972, Detecting and 

treating organic taste and odor compounds in the Missouri 

river: Journal of the American Water Works Association, v. 

64, p. 505-511. 

Romano, R. H., and Safferman, R. S., 1963, Studies on 

Actinomycetes and their odors: Journal of the American 

Water Works Association, v. 55, p. 169-176. 

Rosen, A. A., Baker, R. A., Cherry, A. J., Jenkins, D., 

Laughlin, H. F., Morris, R. L., Collins, R. P., and 

Lechevalier, H., 1970, Research on tastes and odors, 

Committee report: Journal of the American Water Works 

Association, v. 62, p. 59-62. 

Rosen, A. A., Peter, J. B., and Middleton, F. M., 1962, Odor 

thresholds of mixed organic chemicals: Journal of Water 

Pollution Control Federation, v. 34, p. 7-14. 

Safferman, R. S., Rosen, A. A., Maskni, C. L., and Morris, M. 

E., 1967, Earthy-smelling substances from a blue-green 

algae: Environmental Science and Technology, v. 1, p. 

429-430. 

C9 

Sigworth, E. A., 1957, Control of odor and taste in water 

supplies: Journal of the American Water Works 

Association, v. 49, p. 1507-1521. 

Silvey, J. K. G., 1959, Algae and associated organisms in water 

supplies-Manual for waterworks operators: Lancaster, 

Pa., Lancaster Press, 123 p. 

Silvey, J. K. G., 1966, Taste and odor: Effect of organisms: 

Journal of the American Water Works Association, v. 58, p. 

706-714. 

Silvey, J: K. G., Glaze, W. H., Hendricks, A., Henley, D., and 

Matlock, J., 1968, Gas chromatographic studies on taste and 

odor in water: Journal of the American Water Works 

Association, v. 60, p. 440-450. 

Silvey, J. K. G., Henley, D. E., and Wyatt, J. T., 1972, 

Planktonic blue-green algae: Growth and odor-producing 

studies: Journal of the American Water Works Association, 

v. 64, p. 35-39. 

Silvey, J. K. G., and .Roach, A. W., 1964, Studies on 

microbiotic cycles in surface water: Journal of the American 

Water Works Association, v. 56, p. 60-72. 

Zoetman, B. C. J., and Piet, G. J., 1972, On the nature of 

odors in drinking water resources of the Netherlands: 

Science of the Total Environment, v. 1, p. 399-410. 

Classification and Fractionation of Organic 

Solutes in Natural Waters 

By Jerry A. Leenheer 

ABSTRACT 

With the increasing interest in organic substances in water, 

there is an increasing need to characterize and identify the 

substances. This paper demonstrates how organic solutes can be 

classified, fractionated, and analyzed ·so that meaningful data 

are obtained. 

INTRODUCTION 

With the recent emphasis upon development of 

the Nation's fossil fuel resources to meet the growing need for energy, those scientists involved with 

water-quality studies are recognizing an increasing 

need for more definitive characterization of 

organic solutes in water so that changes in water 

quality due to organic residuals inputs can be 

determined. The need for organic solute 

characterization has long been recognized, but 

progress has been slow relative to inorganic solute 

characterization for the following reasons: 

1. The large number of both known and unknown 

organic compounds which may be found in 

water make specific compound identification 

and quantification extremely difficult. 

2. Organic solute concentrations in water are 

usually less than inorganic solute concentrations by two or more orders of magnitude. 

3. Many organic solutes are unstable or volatile, 

which leads to water sampling and preservation problems. 

4. Analytical instrumentation needs for organic 

solute characterization are usually complex, 

expensive, and often inadequate. 

The following brief discussion is intended to 

present a simplified scheme of organic solute 

characterization which attempts to minimize these 

problems. 

ORGANIC SOLUTE CLASSIFICATION 

Although there is no single generally accepted 

classification scheme for organic compounds, 

separation techniques based on solubility and acidbase behavior have been in use for many years 

(figure 1) (Shriner and Fuson, 1940). These 

separation-classification schemes are useful, and 

indeed, are usually a necessary step in the 

identification of unknown organic compounds. 

However, they are time consuming, offer no means 

of concentrating the organic solutes, and do not 

relate the quantity of various subgroups to the 

total amount of organic solutes present. The 

development in recent years of instruments to 

rapidly determine dissolved organic carbon with 

precision and accuracy, as well as the development 

of synthetic resin adsorbents which concentrate 

and fractionate organic solutes by selective adsorption and desorption, permit greater utulization of 

these techniques in studies of organic solutes in 

water. 

The present state of organic solute 

characterization is described graphically in a 

report by Christman and Hrutfiord (1973). They 

state that the development of organic waterquality standards have "* * * occurred on a 

piecemeal basis in response to current crises. At 

one time or another, scientific teams have 

deliberated the significance of and have established water-quality standards for specific compounds such as nitrilotriacetate (NTA) and phthalic 

acid; certain classes of compounds such as 

pesticides, phenols, polychlorinated biphenyls, 

phthalate esters, oil, and grease; and poorly defined groups of compounds known primarily by 

their properties or manner of isolation such as 

foaming agents, color, taste and odor, as well as 

the carbon adsorbable organics * * * " 

Cll 
Ether 

s~nsol. 

sl s2 

Water-Soluble 

Compounds 

DETERMINATION OF SOLUBILITY 

NaHC03 

~L 

At A2 

Acidic 

Compounds 

N1 N2 I 

Neutral Inert 

neous Compounds Compounds pounds Compounds 

M 

Basic MiscellaComClass S1 : Almost all compounds of low molecular weight except (a) low-molecularweight hydrocarbons and their halogen derivatives and (b) low-molecular-weight compounds 

which are strongly polar. 

Class S2 : Water-soluble salts of all kinds, many polyhydroxy compounds, polybasic 

acids, hydroxy acids, amino acids, some amides, amines, and sulfur derivatives. 

Class A1 : Acids and a few negatively substituted phenols such as picric acid. 

Class A2 : Weakly acidic compounds such as oximes, imides, amino acids, sulfonamides or 

primary amines, primary and secondary nitro compounds, enols, phenols, and certain 

mercaptans. 

Class B: Amines except diaryl- and triarylamines. 

Class M: Nitro compounds, amides, negatively substituted amines, nitrites, azo 

compounds, hydrazo compounds, sulfones, sulfonyl derivatives of secondary amines, 

mercaptans, thioethers, and others. 

Class N 1 : Alcohols, aldehydes, methyl ketones, alicyclic ketones, and esters with fewer 

than 9 carbon atoms. 

Class N 2 : All aldehydes, alcohols, ketones, and esters with more than 9 carbon atoms, 

quinones, ethers, and unsaturated hydrocarbons. Anhydrides, lactones, and acetals may be 

found here as well as in Classes S1 and N 1 • 

Class 1: Saturated aliphatic hydrocarbons, aromatic hydrocarbons, and halogen 

derivatives of these constitute the inert class. 

FIGURE 1.-Solubility classification of organic compounds. (Modified from Shriner and Fuson, 1940.) 

C12 
Characterization schemes based on these standards limit themselves for the following reasons: 

1. They are not comprehensive schemes designed 

to cover all organic solutes in water. 

Therefore, they apply only to the specifics for 

which they were designed, and many organic 

solutes are not detected or even suspected. 

2. A materials balance based on organic carbon is 

not used. Therefore, one has no idea how the 

specific compounds and compound classes 

relate to the total organic solute concentration. 

3. Many of the parameters such as color, taste 

and odor, and oils and grease are outdated 

and nonspecific. 

4. Most organic solute characterization schemes 

are based on methodology which incorporates 

the liquid-liquid extraction or carbon adsorption to extract and concentrate organic 

solutes, prior to analysis. Both of these 

analytical techniques have their limitations 

and drawbacks. 

Liquid-liquid extraction is an efficient method for 

extracting certain classes of organic solutes from 

water; particulary those nonpolar solutes which 

have low-water solubility and high solubility in 

organic solvents immiscible with water (ASTM 

Method D-2778, 1975). However, liquid-liquid extraction is relatively ineffecient as a method for 

extraction of highly polar organic solutes which 

prefer the aqueous phase. Highly polar organic 

solutes comprise a significant proportion of 

organic compounds found in natural waters and include polybasic acids, hydroxy acids, polybasic 

alcohols, polysaccharides, and amino acids. An examination of the organic solute distribution 

coefficients listed in the International Critical 

Tables (Forbes and Anderson, 1928) shows that 

these types of highly polar compounds are not 

significantly extractable by organic solvents which 

are immiscible with water. 

Adsorption of organic solutes from aqueous solution upon granular activated carbon currently is 

the most widely used method of concentrating and 

fractionating organic solutes (ASTM Method 

D-2910, 1975). Activated carbon is unsurpassed as 

an agent which removes organic solutes from 

water by adsorption; however, its use in quantitative analytical schemes is limited by the fact 

that many organic solutes are adsorbed irreversibly upon and altered by the activated carbon. The 

limitations are documented in the literature (Baker 

and Malo, 1967; Burnham and others, 1973.) 

In a comparison of processes which concentrate 

organic solutes found in natural water, adsorption 

is inherently superior to liquid-liquid extraction, 

flash evaporation, freeze concentration, and freeze 

drying for the following reasons: 

L It is a low-energy process which does not involve a phase transition. Adsorption does not 

remove the organic solute from the aqueous 

environment as does liquid-liquid extraction 

and freeze drying, and it takes less energy for 

a solute to be adsorbed on a surface than to 

cross a liquid-liquid interface. Extraction into 

a different solvent also often alters the 

chemical nature of the solute. The low 

temperature and high vapor pressure at 

which adsorption occurs prevents losses of 

volatile solutes which are lost during flash 

evaporation or freeze drying. 

2. Adsorption is selective. Adsorbents can be 

selected, such that organic solutes are 

separated from inorganic solutes, and organic 

solutes can be fractionated into different 

groups depending upon which adsorption 

mechanism is used. Flash evaporation, freeze 

concentration, and freeze drying indiscriminately concentrate both organic and 

inorganic solutes, such that reactions between the solutes often occur during 

concentration. 

The main disadvantage of adsorption is that frequently it is irreversible, as often occurs on activated carbon and certain exchange resins. Irreversible adsorption usually is due to the 

heterogenous nature of the adsorbent's surface 

which binds the adsorbed solute by multiple adsorption mechanisms. An adsorbent used for 

analytical concentration and separations should 

have a homogeneous surface, such that only one 

adsorption mechanism is operative so that solutes 

can be quantitatively desorbed for analysis. 

A proposed classification scheme for organic 

solute characterization based on resin adsorbents 

is given in figure 2. This classification scheme has a 

logical progression from one level of specificity to 

the next, and it uses materials balance based on 

organic carbon to quantify organic solute concentrations and fractionations. The organic load 

parameter, dissolved organic carbon, is very 

specific for organic solutes. The meaning and 

significance of the dissolved organic carbon 

parameters is discussed in a report by Malcolm and 

Leenheer (1973). 

C13 
0 

...... 

~ 

1. Organic load parameter ---------- - ------ ---- Dissolved organic carbon 

2. Solute sorption parameters- - - - - - - (a) Hydrophobic organic carbon (b) Hydrophilic organic carbon 

3. Solute acid-base characteristics based on organic carbon - -(a) Acids 

"' II\ 

I I \ 

I I \ 

I I \ 

4. Solute compound classes---- Anionic 

detergents 

5. Specific solute compounds __ _ 

6. Solute complexes (both 

organic and inorganic) _____ 

/I' "' 

I I \ I \ 

I 

~ 

II\ 

I I \ I I \ 

I I \ 

(b) Neutrals 

/I\ "' I I \ I \ 

I I 

I 

Chlorinated 

hydrocarbon 

insecticides 

-1. 

II\ 

I I \ 

I I \ 

I I 

/I\ "' 

I I \ 

I I \ 

I I \. 

(c) Bases 

"" II\ 

I I \ I I \ 

I I \ 

Polynuclear 

a mines 

II\ "' 

I I \ 

I I \ I \ 

1\ 

'I\ 

I I \ I \ 

I : \ 

(d) Acids 

.+._ 

II \ 

I I \ 

I I \ 

I I \ 

Polyuronic 

acids 

.f\ 

1 I \ 

I I \ 

I I \ 

I \ 

.f\ 

I I \ 

I I \ 

I \ 

I : \ 

FIGURE 2.-Proposed classification scheme for organic solute characterization. 

(e) Neutrals 

II\ 

I I \ 

I I \ 

I I ' 

I I \ 

Polysaccharides 

I 

I 

fl., 

I I \ 

I I \ 

I I \ 

~ 

f., \ 

I I \ I ' I \ 

(f) Bases 

1-. ,,, 

I I \ 

I I \ 

I I \ 

Amino 

sugars 

.f\ 

/I \ 

I I \ 

I I \ I 

A. 

II\ 

I. I \ 

I I \ 

I 

>-

... 

·u 

'+= ·u 

Q) 

a. 

Ill 

bD 

c .iii 

n3 

Q) 

..... 

u 

c 
The two solute sorption parameters refer to 

mechanisms by which organic solutes interact with 

each other and with sediment. Hydrophobic organic solutes have hydrocarbon portions of their 

molecular structure which repel water and are attracted to hydrocarbon surfaces on sediment or to 

hydrocarbon portions of other solute molecules. 

The attraction mechanism involves physical adsorption which also is referred to as Van de W aal's 

forces. Hydrophilic organic solutes have waterattracting oxygen, nitrogen, or sulfur-containing 

functional groups over the entire molecular structure such that no part of the molecule can act in a 

hydrophobic manner. Hydrophilic solutes interact 

with each other and with sediments through 

hydrogen-bonding and ion-exchange mechanisms. 

Most hydrophobic organic solutes have hydrophilic 

portions to their molecular structure which render 

them water soluble. Organic detergents have a 

hydrophilic functional group for water solubility 

and a hydrophobic hydrocarbon component to attract hydrocarbon oils and render such substances 

water soluble. Hydrophobicity and hydrophilicity 

are opposite properties and organic solute analysis 

is greatly faciliated, if the solutes are first divided 

into these two classes. 

The third level of classification refers to organic 

solute acid-base characteristics. Organic acids act 

as anions and organic bases act as cations. Many 

organic acids and bases are ionized only at extreme 

pH values, and act as neutral compounds at 

nominal pH values. Neutral organic compounds 

may lack acid or base functional groups, or they 

may have an equal number of acid and base groups 

which neutralize each other to give a neutral compound. Amino acids are such compounds. Organic 

solutes have been classified and separated into six 

groups which are very similar in their chemical 

reactivity. 

Compound class analysis at the fourth level of 

classification is greatly facilitated by the previous 

separations which have removed most of the interfering organic and inorganic solutes. For example, all the chlorinated hydrocarbon insecticides 

will be found in the neutral hydrophobic groups 

with many interfering organic solutes and all inorganic solutes separated. Certain compound 

classes will be found in multiple groups at the third 

level of classification. For example, most amino 

acids will fall into both hydrophilic acid and base 

groups, but the amino acid phenylalanine will fall 

into the hydrophobic acid group because of the 

hydrophobic phenyl ring. 

The last two levels of classification, specific 

solute compounds and solute complexes, demand 

more in the way of analytical requirements than 

may be necessary for some water-quality studies. 

However, if a water-quality study needs to get this 

specific, the proposed classification scheme lays a 

meaningful groundwork for quantitative organic 

solute analysis. An important point to realize in 

this classification scheme is that it serves as a 

preparative analytical scheme as well. Each 

classification level serves as the preparative step 

for the next level. 

ORGANIC SOLUTE FRACTIONATION AND 

ANALYSIS 

For a classification scheme to have utility and 

meaning, it must be based on methodology which 

separates the individual elements into the various 

classification groups. The analytical fractionation 

scheme which separates organic solutes up to the 

third level of classification (dissolved organic carbon fractionation analysis), is diagrammed on the 

flow chart of figure 3. 

Water samples are collected in a 1-liter glass bottle specially prepared for the collection of pesticide 

water samples. The samples are preserved during 

shipment to the laboratory by chilling the samples 

on ice to 4 °C. Immediately upon receipt of the 

samples in the laboratory, all suspended particulate matter greater than 0.45 p.m in diameter 

should be removed. All organic constituents which 

remain in the water sample after separation arbitrarily are called dissolved, despite the fact that 

there is no discrete break between the particulate 

and dissolved states of matter. The arbitrary break 

at 0.45 p.m between sediment and solute was a 

widespread concensus among hydrologists involved with water-quality investigations. 

Dissolved organic carbon (DOC) is the parameter 

used to determine organic solute fractionation to 

the third level of classification. DOC can be determined to a sensitivity limit of 0.1 mg/L with a 

precision of ± 10 percent (Malcolm and others, 

1973). If only dissolved organic carbon fractionation analysis is desired, 1liter of sample is required 

if the DOC falls between 3 and 30 mg/L. Greater 

sample volumes are required for DOC concentrations lower than 3 mg/L, and lesser volumes for 

DOC in excess of 30 mg/L. 

Hydrophobic organic solutes are defin!d quantitatively by the amount of DOC which is adsorbed 

upon XAD hydrophobic macroreticular resins 

placed in a glass column. This definition is 

C15 
Analytical scheme 

Water sample 

1 

Sediment +---- Centrifugation 

Recycle 

acidified sample 

t 

1 

Determine DOC 1 

1 

Stratified XAD-resin column 

(2.5 g XAD-8 over 2.5 g XAD-2) 

I 

Adjust to pH 2 I Backflush column 

with 50 ml 0.1 M HCI with HCI 

\I! 

Determine DOC2 ~ 

Backflush column 

with 50 ml 0.1 M NaOH 

Determine DOC3 •::::=---....J 

Determine DOC4, 

l 

5 g Bio-Rad AG MP-50 

cation-exchange resin 

(H form) 

l 

Determine DOCS 

5 g Bio-Rad AG MP-1 

anion-exchange resin 

(OH form) 

l 

Determine DOC6 

Parameters (mg/L) 

A. Total hydrophobic DOC=D0Cl-DOC4 

B. Total hydrophilic DOC=DOC4 

1. Hydrophobic base 

DOC=(DOC2x0.05)1sample volume 

2. Hydrophobic acid 

DOC=(DOC3 x0.05)/sample volume 

3. Hydrophobic neutral DOC=A-1-2 

4. Hydrophilic base DOC=DOC4-DOC5 

5. Hydrophilic acid DOC= DOC5-DOC6 

6. Hydrophilic neutral DOC= DOC6 

FIGURE 3.-Fractionation-analysis flow chart for dissolved organic carbon. 

C16 
admittedly method dependent upon the analytical 

fractionation scheme given in figure 3. The 

mechanisms and methodology of hydrophobic organic solute adsorption is discussed by Junk and 

others (197 4). Hydrophobic organic bases are 

separated by desorption from the resins with 0.1 M 

HCl and hydrophobic acids are separated by 

desorption using 0.1 M NH4 OH as the eluent. 

Hydrophobic organic neutral solutes remain on the 

column, and they are quantified by DOC differences. Most hydrophobic neutral solutes are 

soluble in organic solvents such as ethyl ether and 

menthanol, which are used as desorption solvents. 

The DOC which remains in the eluent from the 

column packed with the XAD resins quantifies the 

hydrophilic organic solutes. Hydrophilic organic 

bases first are separated by passing the water sample through a glass column packed with a 

hydrogen-saturated cation-exchange resin which 

adsorbs organic bases which are protonated cations at sample pH 2. Hydrophilic organic acids 

next are separated in a similar manner by adsorption on a hydroxide-saturated anion-exchange 

resin. The DOC remaining in solution after the entire resin-adsorption procedure quantifies 

hydrophilic organic neutral solutes. Hydrophilic 

organic bases can be desorbed and eluted from the 

cation-exchange resin by 1 M NaOH and 

hydrophilic organic acids can be displaced from the 

anion-exchange resin by 1 M HCl. The many applications of ion-exchange resins for analytical 

separations are discussed by Khym (1974). 

The analytical determination of selected organic 

compounds at the fourth level of classification can 

be performed directly on the appropriate fraction 

derived from the DOC fractionation analysis. 

Fairly specific colorimetric methods exist for 

anionic detergents, phenols, polysaccharides, 

polyuronic acids, amino acids, and others. The 

DOC fractionation analysis greatly aids the compound class analyses because the resin adsorption 

precedure serves to concentrate trace organic 

solutes, and the resultant fractionation removes 

many organic and inorganic interferents. Only the 

hydrophilic organic neutral solute fraction is not 

concentrated by DOC fractionation analysis, and 

this fraction can be effectively freeze concentrated 

because most of the inorganic solutes which form 

precipitates when freeze concentrated, have been 

removed previously by ion exchange. The 

methodology and limitations of freeze concentration are discussed by Baker (1969). 

The analytical determination of certain compound classes, specific organic solute compounds, 

and organic solute complexes usually demands additional fractionation by either liquid or gas 

chromatograph. Only about 10 percent of organic 

solute compounds are sufficiently volatile to be 

fractionated by gas chromatography; the remaining 90 percent must be fractionated by liquid 

chromatography. An excellent text on gas 

chromatography is by McNair and Bonelli (1969), 

and liquid chromatography is discussed by Hadden 

and others (1971). Most of the volatile organic 

solutes, such as various pesticides and hydrocarbons, are found in the hydrophobic neutral fraction. The volatility of organic solutes in the other 

fractions frequently can be enhanced by making 

nonpolar derivatives which have a greater volatility, thus making gas chromatography of these 

solutes possible. Gas chromatography still is 

preferred to liquid chromatography as a means of 

organic solute fractionation because of its greater 

versatility due to the absence of solvent during 

solute separation, and because of the greater 

number and sensitivity of solute detectors. 

Final identification of specific organic solutes 

and solute complexes usually is accomplished by 

obtaining spectral information on the pure organic 

solute. Mass spectra, infrared spectra, nuclear 

magnetic resonance spectra, and ultraviolet-visible 

spectra are the most generally used spectra for 

identification purposes. Gas or liquid chromatography also can be used to identify an organic 

solute by comparison of its fractionation characteristics with the fractionation characteristics of 

various organic solute standards. 

APPLICATION OF ORGANIC SOLUTE 

CLASSIFICATION SCHEME 

This paper is the first written communication 

about the proposed organic solute classification 

scheme; therefore, the data which follow are 

limited to a few samples which were processed by 

the DOC fractionation analysis to test levels 1-3 of 

classification scheme. Hopefully, these data will 

provide an indicator of how the organic solute 

classification scheme can be used, applied, and interpreted in water-quality studies. 

The first natural water samples to be processed 

by part of the DOC fractionation analysis were two 

ground-water samples. The samples were collected 

to observe changes in organic solute composition 

which occurred when a coal seam about 90 m below 

land surface was ignited in a U.S. Bureau of Mines 

in situ coal gasification experiment. When the burn 

was extinguished, ground water flooded the 

C17 
burned zone and became contaminated with 

organic combustion products. The data are 

presented in table 1. Sample 1 is uncontaiminated 

ground water withdrawn from the coal seam outside the burned area. Sample 2 is contaminated 

ground water withdrawn from a well in the center 

of the burned area. 

TABLE 1.-DOC fractionation analysis of Wyoming groundwater samples 

Sample 1 Sample 2 

(uncontaminated) (contaminated) 

Specific Conductance 

(p. ho/cm@ 25°C) ------------- 1,050 2,050 

pH (Units)--------------------- 8.0 8.4 

Initial DOC (mg/L) -------------- 42.0 22.0 

Hydrophobic DOC (mg/L) ________ 26.0 11.0 

Hydrophilic DOC (mg/L) _________ 16.0 11.0 

Hydrophobic acid DOC (mg/L) _____ 10.5 8.6 

Hydrophobic neutral DOC (mg/L) __ 15.2 2.3 

Hydrophobic base DOC (mg/L) ____ .3 .1 

Hydrophobic DOC (percent of initial 

DOC) ----------------------- 61 50 

Hydrophilic DOC (percent of initial 

DOC) ----------------------- 39 50 

Acid solutes (percent of 

hydrophobic DOC) ------------- 40 78 

Neutral solutes (percent of 

hydrophobic DOC) ------------- 59 21 

Base solutes (percent of 

hydrophobic DOC) ---------- __ 1 1 

The data in table 1 could be interpreted in the 

following manner. The greater ratios of 

hydrophobic:hydrophilic DOC in sample 1 most 

likely indicate that the DOC of the uncontaminated 

sample is more hydrocarbon (hydrophobic) in 

nature, and is at a lower oxidation state as compared to the contaminated sample 2. Most likely, 

the combustion of coal during gasification gave 

rise to organic solutes with a higher oxidation state 

(more acids), and a greater polar functional group 

content (more hydrophilic) as compared to organic 

solutes in the uncontaminated ground water. The 

elemental carbon which resulted from the carbonization of coal during gasification also may 

have adsorbed some of the hydrophobic solutes in 

contaminated sample 2, such that the hydrophobic 

DOC concentration is reduced. In this case, DOC 

fractionation analysis showed large fraction ratio 

changes which can be interpreted in terms of 

organic solute changes. 

The last sample processed by DOC fractionation 

analysis illustrates an application to studies involving organic-inorganic complexes. In a study of 

ground water of high selenium content near 

Golden, Colorado, it was noted that several 

samples contained high concentrations of DOC, as 

well as selenium. An experimental procedure 

based on DOC fractionation analysis was designed 

to observe also selenium fractionation both in the 

natural ground water and in a synthesized water 

sample which contained similar concentrations of 

selenium and other inorganic solutes with no DOC. 

Comparison of the data for the two samples should 

allow certain conclusions about the association between DOC and selenium. The data are presented 

in table 2. 

TABLE 2.-DOC fractionation analysis and selenium fractionation analysis of Colorado ground-water samples 

Sample 1 Sample 2 

(ground water) (Se standard) 

Specific Conductance 

(p. hos/cm at 25°C) ------------- 4,300 4,800 

pH (Units)--------------------- 7.1 7.5 

Initial Se (p. g/L) ---------------- 200 240 

Initial DOC (mg/L) -------------- 10.0 0 

Hydrophobic DOC (mg/L) ________ 5.8 0 

Hydrophilic DOC (mg/L) --------- 4.2 0 

Hydrophobic acid DOC (mg/L) ____ 3.4 0 

Hydrophobic neutral DOC (mg/L) __ 2.4 0 

Hydrophobic base DOC (mg/L) ____ 0 0 

Hydrophilic acid DOC (mg/L) _____ 3.7 0 

Hydrophilic neutral DOC (mg/L) ___ .5 0 

Hydrophilic base DOC (mg/L) _____ 0 0 

Se after hydrophobic base and 

neutral DOC extraction (p. g/L) __ 200 380 

Se after hydrophobic acid DOC 

extraction (p. g/L) ------------- 240 240 

Se after hydrophilic base DOC 

extraction (p. g/L) ------------- 260 300 

Se after hydrophilic acid DOC 

extraction (p. g/L) ------------- 6 12 

Se found in hydrophobic acid DOC 

extract (p. g/L) ---------------- 1.3 

Se found in hydrophobic neutral 

DOC extract (p. g/L) ----------- 0 

The data clearly show that only minor amounts 

of selenium were associated with the hydrophobic 

organic soluted fractions which comprise 58 percent of the total DOC. Almost all of the selenium 

was adsorbed from both samples as an anion on the 

anion-exchange resin. Because the fractionation of 

selenium in sample 2, which contained only inorganic solutes, was identical to the selenium fractionation of sample 1 which was the ground water, 

it is virtually certain that selenium in the ground 

water is not directly associated with organic 

solutes. This is not a surprising conclusion because 

most organic solutes and selenium solutes have 

anionic natures which discourage complex formation. 

CONCLUSION 

This paper has shown how organic solutes can be 

classified, fractionated, and anlayzed so that meanC18 
ingful data are obtained without resorting to 

highly complex organic analyses. DOC fractionation analysis should be useful for indicating 

relative abundances and changes in composition of 

organic subgroups, and a "finger-printing'' tool for 

various waters. DOC fractionation analysis also 

can be used as a preparative procedure for additional analyses ultimately leading to specific compound and compound-style identification. 

REFERENCES CITED 

American Society for Testing and Materials,1975, Annual Book 

of ASTM Standards-Water, Part 31: Philadelphia, 

American Society for Testing and Materials, 922 p. 

Baker, R. A., 1969, Freeze concentration of microorganics in 

water: American Society for Testing and Materials, Special 

Technical Publication 448: p. 65-77. 

Baker, R. A., and Malo, B. A., 1967, Water quality characterization-Trace organics: Journal of the Sanitary Engineering 

Division, American Society of Civil Engineering, v. 93, no. 

6, p. 41-54. 

Burnham, A. K., Calder, G. V., Fritz, J. S., Junk, G. A., Svec, H. 

J., and Vick, R., 1973, Trace organics in water: Their isolation and identification: Journal of the American Water 

Works Association, v. 65, no. 11, p. 722-725. 

Christman, R. F., and Hrutfiord, B. F., 1973, Water-quality 

standards for organic contaminants: Analytical limitations 

and possibilities: American Water Works Association, Proceedings of 15th Water Quality Conference, Urbana, Ill., 

Dec. 1973, p. 63-72. 

Forbes, G. S., and Anderson, G. W., 1928, Phase-equilibrium 

data for condensed systems containing two liquid phases 

with a third component in distribution equilibrium between 

the two liquid phases being practically nonmiscible-Distribution coefficients: International Critical 

Tables, v. 3, p. 418-435. 

Hadden, N., Baumann, F., MacDonald, F., Munk, M., Stevenson, R., Gere, D., Zamoroni, F., and Majors, R., 1971, Basic 

liquid chromatography: Walnut Creek, Calif., Varian 

Aerograph Corp., 253 p. 

Junk, G. A., Richard, J. J., Grieser, M. D., Witiak, J. L., 

Arguello, M. D., Vick, R., Svec, H. J., Fritz, J. S., and 

Calder, G. V., 1974, Use of macroreticular resins in the 

analysis of water for trace organic contaminants: Journal of 

Chromatography, v. 99, p. 745-762. 

Khym, J. X., 1974, Analytical ion-exchange procedures in 

chemistry and biology: Englewood Cliffs, N.J., PrenticeHall, Inc., 257 p. 

Malcolm, R. L., and Leenheer, J. A., 1973, The usefulness of 

organic carbon parameters in water quality investigations: 

Institute for Environmental Sciences, Proceedings, 

Anaheim, Calif., April1973, p. 336-340. 

Malcolm, R. L., Leenheer, J. A., McKinley, P. W., and Eccles, 

L.A., 1973, Supplement 11-0rganic carbon, in Goerlitz, D. 

F., and Brown, E., eds., Methods for analysis of organic 

substances in water: U.S. Geological Survey Techniques of 

Water-Resources Investigations, Book 5, Chapter A3, 34 p. 

McNair, H. M., and Bonelli, E. J., 1969, Basic gas 

chromatography: Walnut Creek, Calif., Varian Aerograph 

Corp., 306 p. 

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-k U.S. GOVERNMENT PRINTING OFFICE: 1981-341-614/238 

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