Biodegradation of alkyl ethoxylates and alkylphenol ethoxylates in river water in a static die-away test as studied by HPLC-ESI/MS

Biodegradation of nonylphenol ethoxylates and dodecyl ethoxylates (C9H19-C6H4- (OCH2CH2)n-OH and C12H25-(OCH2CH2)n-OH, respectively) in river water in a static die-away test was analyzed by using high performance liquid chromatography with mass spectrometric detection using the Applied Biosystems quadrupole-linear ion trap mass spectrometer Model 4000 QTrap. Surfactants containing 2-4 ethoxylene units may be regarded as persistent metabolites of longer surfactants. Homologues C9H19-C6H4- (OCH2CH2)5-OH and C12H25-(OCH2CH2)5-OH underwent substantial biodegradation till the 9th day of the test, their further biodegradation proceeded very slowly. The longer homologues (n > 5) were fully biodegraded during the test. Although the biodegradation of the surfactants studied consisted in shortening the ethoxylene chain (hydrophilic part), it was found that the hydrophobic part also affected their biodegradation.