Analysis of nonylphenol polyethoxycarboxylates and their related metabolites by on-line derivatization and ion-trap gas chromatography-mass spectrometry

This study presents a modified method to analyze nonylphenol polyethoxycarboxylates (NPEC) and their related metabolites (carboxyalkylphenol ethoxycarboxylates (CNPEC)) in water samples. The method involves extraction of samples by a graphitized carbon black (GCB) cartridge, and direct derivatization in the GC injection-port using a large-volume (10-20 mu l) direct sample introduction (DSI) device with tetraalkylammonium (TAA) salts. The analytes are identified and quantitated by ion-trap GC-MS. The large-volume DSI injection-port derivatization technique provides sensitivity, fast and reproducible results for NPEC and their metabolites, to quantitation at 0.1 mu g/l in 200 mi of water samples. The retention effect of TAA salts in the injection-port is not detected. In addition, the significant [M-29](+) ions and molecular ions of butylated NPEC and CNPEC residues are observed. Recovery of NP1EC in spiked water samples ranges from 90 to 108%. Moreover, relative standard deviations of replicate analyses ranges from 1 to 9%. However, unsatisfactory on-line derivatization of CNPEC residues is observed. This finding maybe owing to their lesser dissociation with the ion-pair reagent in chloroform. (C) 1999 Elsevier Science B.V. All rights reserved.