Determination of aromatic primary amines at μg 1-1 level in environmental waters by gas chromatography-mass spectrometry involving N-allyl-N′-arylthiourea formation and their on-line pyrolysis to aryl isothiocyanates

Derivatization of aromatic primary amines to N-allyl-N'-arylthioureas by reaction with allyl isothiocyanate and GC-MS of the derivatives, when pyrolysis to aryl isothiocyanates occurs in the heated injector, has been used to determine aromatic amines in the range 0.5-50 mug l(-1) with a correlation coefficient, r, in the range 0.9902-0.9992. The limit of detection ranged 8 to 30 ng l(-1) when 60 ml of sample were preconcentrated, after derivatization, on a styrene-divinylbenzene copolymer sorbent. The pyrolytic cleavage of sym- and unsym-diaryl or alkyl-/arylthioureas has been rationalized. The chromatography of isothiocyanates is much superior to that of aryl amines and the specific mass fragmentation pen-nits positive identification of amines. The method has been applied to spiked drinking water, groundwater and river water samples, when the recovery ranged from 84 to 109% with RSD of 5-9%, and to detect aromatic amines formed by reductive cleavage of azo dyes in effluents when the recovery of amine was in the range 81-95% with RSD 8-15%. The method is not applicable to nitroanilines. (C) 2003 Elsevier B.V. All rights reserved.