Novel design for drift tubes in ion mobility spectrometry for optimised resolution of peak clusters

In the past decade, Ion Mobility Spectrometry has established a very strong foot hold in medical and biological applications due to its numerous advantages including sensitivity, ruggedness and reproducibility. During the analysis of complex samples such as human breath, it is very probable that two or more analytes form peak clusters due to similar drift times and pre-separation times, thus hindering the identification of the analytes. Furthermore, such overlapping of signal makes quantification very difficult or even impossible. Resolving these peak clusters is important to enable proper identification and quantification of analytes detected for diagnosis. Hence, we designed a drift tube with variable length for investigating the influence of varying drift lengths and electric field on resolution. Peak cluster formations usually seen between acetone and the reactant ion peak, between the dimer peaks of 2-Heptanone and 4-Heptanone have been resolved with the new drift tube after optimisation. These novel drift tubes could easily negate the peak clusters often encountered when complex medical and biological samples are measured with the ion mobility spectrometer. Furthermore, the fact that these drift tubes can be altered in length thereby providing a wide range of electric fields (from 50 to 3300 V.cm⁻¹), opens up new research options in ion motions in an electric field.