Resistance of alkylphenol ethoxylate containing six ethoxylene units to biodegradation under the conditions of OECD (Organization for Economic Co-operation and Development) screening test

Biodegradation of a commercially available mixture of octylphenol ethoxylates (Triton X-100) under the condition of OECD 301E screening test was studied by using electrospray ionisation mass spectrometry. It was found that ethoxylate containing six ethoxylene units (OPEO6) is more resistant to the biodegradation process than other ethoxylates (e.g. than OPEO5 and OPEO7). After 40 days of biodegradation process the signal of OPEO6 was clearly seen, but signals of OPEO5 and OPEO7 were not detected. After 40 days, all OPEOn with n > 4 were converted into carboxylated derivatives. Carboxylated derivatives were observed in negative ion mode as OPEOn-CH2COO− ions. Biodegradation of OPEO5-CH2COOH (carboxylated derivative correspondent of OPEO6) occurred slower than biodegradation of the others, as resulted from obtained ESI mass spectra.