Determination of heterocyclic amines by liquid chromatography–quadrupole time-of-flight mass spectrometry

This paper discusses the applicability of coupling liquid chromatography (LC) to mass spectrometry (MS) using a time-of-flight (TOF) mass analyzer for the analysis of heterocyclic amines (HAs). Accurate mass measurement (<2 mDa) with both MS–MS and in-source CID MS–MS was carried out to confirm the elemental composition of some fragments previously reported. Some isobaric assignments (fragments containing N versus CH2 and NH3 versus CD2H) were distinguished by taking advantage of the resolution provided by the TOF mass analyzer. On the other hand, the LC–MS analysis of HAs in MS acquisition mode was also performed. Quality parameters of the method were established. The linearity range extended over three orders of magnitude, limits of detection were in the pg level and good short-term precision values (R.S.D., 1.2–8.0%) were obtained. The LC–ESI-TOF method was applied to the determination of HAs in a lyophilized meat extract and the results obtained were comparable to those given by MS–MS with triple quadrupole and ion trap instruments.