Fourier transform ion mobility spectrometry of barbiturates after capillary gas chromatography

This paper demonstrates a novel operating mode of an ion mobility detector (IMD) for obtaining both qualitative and quantitative data after capillary gas chromatographic separation of 5,5′‐disubstituted barbiturates. Using a recently developed time dispersive Fourier transform method for ion mobility spectrometry, complete ion mobility spectra could be obtained for each component in the chromatogram. This type of spectra can be used for providing qualitative information on unknown compounds or for selecting the proper detector conditions needed when operating in the continuous mobility monitoring mode. In this study each of the five barbiturates investigated produced a Fourier transformed ion mobility spectrum containing one major product ion. When drift times corresponding to those of the product ions measured in the FT mode were monitored continuously, selective chromatographic detection of the barbiturates was achieved. In one case even isomers could be differentiated based on mobility characteristics.