Page 199 - Geochemistry of Oil Field Waters

186 ORGANIC CONSTITUENTS IN SALINE WATERS

in soils. Later, Page and Dutoit (1930) modified the name humus acid to
humic acid. Sestini (1898) demonstrated that the humic acids are of com-
plex composition and contain ethereal and anhydride components in
addition to alkyl, hydroxyl, and ketonic groups.
Burges (1960) suggested that humic acid is a single chemical substance or
a group of similar substances, and that primarily it is nonnitrogenous.
Steelink et al. (1960) fused soil humic acids and found the following degra-
dation products: catechol, profocatechuic acid, and resorcinol. Steelink and
Tollin (1962) determined the presence of two free-radical species in humic
acid using an electron paramagnetic-resonance spectrometer. They believed
that one could be a semiquinone radical and the other a quinhydrone radical.
Fulvic acids, humic acids, and hymatomelanic acids have been found in
natural waters (Wilson, 1959; Black and Christman, 1963; Packman, 1964).
The brown color, characteristic of many natural waters, is attributed to
complex organic compounds which probably are derived from water-soluble
peptizable components of soil humus.
A method that can be used to determine the organic acids in petroleum-
associated waters was published by the Natural Gasoline Association of
America (1953). The water is treated with lime water to convert the organic
acids to their calcium. salts, which are titrated with a standard mineral acid.

Determination of oil in water

The following method was developed by Nalco Chemical Company (1971)
and is applicable to waters and brines where the oily matter is hydrocarbons
or hydrocarbon derivatives and all liquid or unctuous substances that have a
boiling point above 90°C and are extractable from waters or brines at pH 5.0
or lower using benzene, chloroform, or carbon tetrachloride.
The sample is extracted with a fluorocarbon solvent which is evaporated
off in a specially designed vessel and the residual oil measured volumetrically
in a microsyringe.

Pear-shoped lop, capacity opprox.17 ml,
offset odditionol opening so th0t"popped"
somple will be retoined

Syringe, 500 kl, 10-pl divisions
Fig. 6.1. Microsyringe-evaporating flask.