RESUMEN
Ammonia desorption chemical ionization (D/CI) tandem mass spectrometry (method A), isobutane D/CI tandem mass spectrometry using reactive collisions with ammonia (method B), and gas chromatography negative CI (GC-NCI) tandem mass spectrometry (method C) were compared for the detection and quantitation of trichothecenes in spiked human plasma and wheat samples. The trichothecenes were analyzed as their heptafluorobutyrate (HFB) esters in method C and without derivatization using the direct exposure probe in methods A and B. The instrument was operated in the multiple reaction mode. With standard solutions, the detection limits were about two orders of magnitude better with method C (0.1-2 pg) than with methods A and B. The trichothecenes could be detected in the spiked samples at lower concentration levels by method C (0.001 microgram g-1) than by methods A and B (0.01-0.1 microgram g-1), since the sensitivity and selectivity of method C were better than those of methods A and B. Because of the need of derivatization, method C was more time-consuming than methods A and B. Iso-T-2 was used as an internal standard in method C and a steroid nandrolone in methods A and B. The linearities and reproducibilities of the quantitation were better with methods A and C than with method B.