Detection of trace levels of trichothecenes in human blood using capillary gas chromatography-electron-capture negative ion chemical ionisation mass spectrometry

A sensitive and selective method has been developed for the simultaneous detection in blood of eleven trichothecenes of widely varying polarity. The procedure involved precipitation of blood proteins with acetone followed by a clean-up using reversed-phase Sep-Pak C18 cartridges. The extracted trichothecenes were derivatised as their pentafluoropropionyl esters, separated using capillary gas chromatography and detected using electron-capture negative ion chemical ionisation with methane reagent gas and selected-ion monitoring. Optimum sensitivity and selectivity were obtained using low source temperatures (60 degrees C indicated) and high source pressures (1 Torr indicated). Detection limits on 1-ml blood samples were in the range 0.1-5 ppb. The method was readily adaptable to the detection of other trichothecenes. A protocol was used which minimised the risk of cross-contamination. The method was validated in collaborative studies by the successful analysis of 42 blood samples spiked and submitted blind by two independent laboratories for analysis.