GC/IMS and GC/MS analysis of pre-concentrated medical and biological samples

Ion mobility spectrometry (IMS) is a well-known analytical method for the detection of CWAs and explosives since many years. Coupling IMS to GC pre-separation, new application fields in medicine and biology could be opened, dealing with complex and humid mixtures. However, identification of unknowns in such a complex sample is challenging and can only be achieved by parallel GC/MS analysis, thus obtaining a proposal for the responsible compound for validation via reference substances by GC/IMS again. The available adsorption tools for such accompanying GC/MS analysis have their particular drawbacks (e.g. problematic quantification for SPME, high sample volumes for adsorption tubes). Therefore miniaturised adsorption needles (NeedleTrap) were applied to both GC/IMS and GC/MS for validation of their reproducibility. It could be demonstrated that the needles can even be used for appropriate quantification when the adsorbent and the sample volume are adapted properly to the concentration range, the compounds of interest and humidity of the sample. The method is very flexible with regard to the concentration range by variation of the sample volume (e.g. 20 mL for pptV, 10 mL for lower ppbV or 1 mL for ppmV) and with regard to the compounds of interest by application of common adsorption materials optimised for the relevant substance group. Such materials are available commercially in a broad variability. Therefore, the miniaturised adsorption needles are a helpful complementary sampling method for any GC/MS or GC/IMS investigations.