Nanoclusters formation in ion mobility spectrometry and change separation selectivity of picoline isomers

Abstract

Ion mobility spectrometry (IMS) was applied to determine the influence of structural features of nanocluster formation of picoline isomers in ion mobility spectrometry. Since the results of our studies show that different isomers have the same mobilities in pure nitrogen buffer gas and their corresponding peaks are totally overlapped, 2-butanol vapor was introduced into buffer gas by means of an online system from 0 to 300 mL min−1. We found different structural features of these isomeric compounds which cause distinct differences in ion mobility spectra. These differences result from the formation of different nanocluster product ions (~1 nm3) with different cross section areas formed depending on the occurrence of certain structural features (position of the methyl group on the pyridine ring). The size of cluster product ions formed was determined using cross section area measurements. The effects of temperature in the range from 80 to 200 °C and electric field strength have also been investigated. At 140–160 °C and 636 V cm−1, optimum peak-to-peak resolution can be obtained.