Determination of 2-substituted benzothiazoles of industrial use from water by liquid chromatography/electrospray ionization tandem mass spectrometry

A method was developed for the analysis of 2-substituted benzothiazoles from wastewaters by reversed-phase liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS). While benzothiazole (BT), 2-amino- (ABT), 2-methyl-, 2-thiocyanomethylthio- and 2-methylthiobenzothiazole were separated with a methanol gradient acidified with formic acid and detected in the positive mode, 2-mercapto- and 2-hydroxybenzothiazole (OHBT) as well as benzothiazole-2-sulfonic acid (BTSA) were separated with the addition of ammonium acetate and detected in the negative ion mode. Detection limits range from 10 ng L(-1) for ABT to 200 ng L(-1) for OHBT after direct injection of 100 µL sample volumes, while BT requires 2.5 µg L(-1). The method is, thus, suitable for direct analysis in wastewaters. Its application to tannery effluent samples revealed, that, besides a 90-95% elimination of total benzothiazoles, the concentration of OHBT and BTSA increased during the biological treatment.