Determination of Organics in Water
JULIAN B. ANDELMAN, Assistant Professor of Water Chemistry
MAURICE A. SHAPIRO, Professor of Sanitary Engineering
THOMAS C. RUPPEL, Senior Research Assistant
The Environmental Health Section
Graduate School of Public Health
University of Pittsburgh
Pittsburgh,  Pennsylvania
INTRODUCTION
The currently most favored method of concentrating organic constituents of
water supplies, with a view to determining their amount and character, is to pass
the water through an activated carbon column on which the organic constituents
are adsorbed (1). A subsequent extraction of the air-dried carbon with several
solvents, usually chloroform and ethanol, removes organic matter from the carbon
in the form of solutions in these solvents. Final evaporation of the solvents produces a concentrate which reputedly represents the organic materials originally
present in the water investigated.
This technique has been used to relate organic water content to taste and odor
(2,3) and to compare the degree of pollution of rivers (4). Although several specific chemicals such as DDT, Aldrin, o-nitrochloro-benzene and phenyl ether
have been recovered with this technique (4) relatively few of the likely contaminants have been identified and quantitatively measured.
A possible disadvantage of this technique is that materials sorbed onto the
carbon surface may oxidize. The oxidative capacity of an activated carbon surface has been demonstrated (5). It has also been shown that phenolic materials
sorbed onto carbon degrade and are recoverable to a lesser extent with increasing
time (6). The air-drying procedure of the carbon filter method may also result
in the distillation of low molecular weight materials from the carbon surface, as
well as chemical reactions of the organics remaining on the surface. In spite of
these possible disadvantages inherent in this technique, no other single method
has been developed with its simplicity and ease of operation.
In this study an attempt has been made to assess the extent of recoverability
of organics as affected by the air-drying process, as well as the possible loss of
materials by evaporation in air drying the carbon prior to extraction. However,
the principal effort has been directed toward the development of sequential extraction of organics by more than one solvent prior to further concentration techniques, followed by the use of gas chromatography in order to identify constituents
of the highly complex trace organic mixture in a municipal water supply.
EXPERIMENTAL
Tap water from one of the three Pittsburgh municipal water supplies was
passed through an activated carbon filter (1) at the rate of 0.25 to 0.5 gpm until
approximately 5000 gals had been filtered in each run. Sand pre-filters were
used along with two parallel carbon filters, each of which contained 250 grams
(dry weight) 30-mesh activated carbon. Following each filtration the activated
carbon containing the organic chemicals sorbed from the water was extracted with
organic solvents using a variety of techniques.
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