Ref ID : 1134
Itoh Shin-ichi, Setsuda Setsuko, Utsunomiya Akiko, and Naito Syoji; [Studies on the biodegradation test method of chemical substances. I. Ultimate biodegradation test of anionic surfactants by the gas chromatographic measurement of CO2 production]. J.Hygienic Chemistry 22(5):254-259, 1976
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A new technique for measuring the rate and degree of ultimate biodegradation (biodegradation to CO2, H2O, and inorganic compounds) of anionic surfactants in water was investigated. Test solution (1700 ml) was incubated in a 3200 ml reaction vessel sealed with a rubber stopper at 27 degrees C under aerobic condition. A given anionic surfactants was biodegraded to CO2; this CO2 was divided according to Henry's law between the liquid phase and the gas phase in the reaction vessel with a constant proportionality. If the CO2 content in either the gas phase or liquid phase is determined, it is possible to calculate the total CO2 content by using a constant proportionality. Therefore, the CO2 content in the gas phase was determined by gas chromatography and the percentage of theoretical CO2 production was calculated. In the second step of this study, a new biodegradation index for estimating the ultimate biodegradability of anionic surfactants was studied. This index was calculated from the equation, Biodegradation index=B/A, where A indicates the theoretical CO2 production of glucose (in %) and B that of an anionic surfactant. If the anionic surfactant is as readily biodegradated as glucose, the theoretical CO2 production will be the same for the two and the index is a unity. An index will be below 1.0 when the surfactant is less readily biodegradated than glucose. Thus, biodegradation index will be useful not only in the estimation of the ultimate biodegradability of an anionic surfactant but also in the comparison of different anionic surfactants in terms of ultimate biodegradability.