Electron-impact fragmentation ofN-substituted 2-aminobenzoxazoles and 2-aminobenzothiazoles

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. Copyright 2000 John Wiley & Sons, Ltd.

Application of mass spectrometry for the analysis of organic tautomeric compounds

Mass-spectral methods for the detection and identification of organic tautomers in the gas phase are reviewed together with the thermochemical and quantum chemical evidence for the stability of the respective tautomeric forms in the gas phase. The literature (approximately 150 references) is covered to 1995. © 1997 John Wiley & Sons, Inc., Mass Spectrom Rev 15(6), 339-363, 1997.

Steroidal thiourea and thiazoline derivatives: synthesis and in vitro effects on bovine pancreatic ribonuclease activity

Two novel series of steroidal derivatives containing various thiourea and substituted thiazoline moieties attached to the 2- or 4-position of estrone were synthesized and examined for in vitro effect on bovine pancreatic ribonuclease activity. All compounds studied exhibited a catabolic activity. The steroidal thiazoline derivatives were more potent activators of ribonuclease than the steroidal thioureas.