ABSTRACT
Before the development of chemical-specific methods for the measurement of Alkylphenol Ethoxylates in biodegradation studies and environmental samples, primary biodegradation was demonstrated by methods that measured the loss of a chemical or physical property of the parent molecule. The two principal physical procedures used to monitor the primary degradation of nonionic surfactants in the laboratory and in environmental samples are measurement of foaming and surface tension. Furthermore, other substances present in environmental samples such as protein, partial degradation products, and other surfactants make quantification impossible. Measurement of nonionics with the foam method is further confounded by the fact that the nonionics are generally low in foaming potential compared to anionic surfactants. The two most widely used analytical tests to determine the primary biodegradability of nonionic surfactants are detection of cobalt thiocyanate and bismuth iodide active substances. Both methods are based on the formation of metal complexes with the oxygen atoms in the polyoxyethylene chain.
