Fate studies of the non-ionic surfactant alkyl glucamide by liquid chromatography/electrospray mass spectrometry

Alkyl glucamides (AGs) were analyzed by reversed-phase liquid chromatograph y (LC) coupled to mass spectrometry with electrospray ionization (ESMS). An alytes were separated according to the chain length of two homologs, C-12- and C-14-glucamide. Mass spectrometric detection in the positive Ion mode e xhibited higher overall sensitivity where, apart from fragments, different molecular and quasi-molecular ions were obtained. However, application of t he negative ion mode offered advantages in terms of reproducibility and ext ent of information when analyzing environmental samples. Therefore, a simpl e and sensitive analytical methodology was developed for the determination of AGs in municipal sen age treatment plant influent and effluent based on solid-phase enrichment, LC separation and negative ion ESMS quantification. lifter preconcentration of 100 mi of aqueous sample, the recoveries using polymeric LiChrolut EN cartridges exceeded 89%. A quantification limit of 0 .1 mu g l(-1) was achieved. Studies on the biodegradability and metabolic p athway of C-10-glucamide were carried out on a laboratory-scale microbial t est unit under aerobic conditions. A postulated metabolism including omega- oxidation of the alkyl chain followed by subsequent beta-oxidations was che cked by LC/ESMS. Identification and formation of 'C-4-glucamide acid' as a degradation intermediate was confirmed by mass spectrometric studies. Highe r homolog acids such as C-10-, C-8- and C-6-glucamide acids, which should b e predicted precursors of C-4-glucamide acid, and any other metabolites, we re not detectable, presumably erring to rapid breakdown. Copyright (C) 2000 John Wiley & Sons, Ltd.