A COMPARISON OF ARTIFACTUAL GC MS RESPONSES WITH SELECTED-ION RECORDING AND MULTIPLE-REACTION MONITORING SCAN MODES/

Selected ion recording (SIR) and multiple-reaction monitoring (MRM) ar e used extensively in conjunction with GC/MS, A comparison of MRM and low and high resolution SIR is presented which contrasts the susceptib ility of the techniques to artefactual responses, An assay developed f or the quantitation of the tert-butyldimethylsilyl (t-BDMS) derivative of thymine glycol was chosen as the test experiment, The effect of th e elution of two unrelated compounds of lower relative molecular mass than the ion to be monitored was then observed. The greatest effect wa s observed with low resolution SIR, where both positive and negative a rtefactual responses were observed in the monitored channels, In high resolution SIR, artefacts were observed in the lock-mass channel only, while in MRM no artefacts were detected. Discussion of the results in cludes the possible role of the column stationary phase in producing t he observed artefacts, together with suggestions for reducing artefact s in GC/MS.