Matrix effects by specific buffer components in the analysis of metabolites with ion trap mobility spectrometry

The impact of buffer conditions on the ion trap mobility spectrometer (ITMS) signal is investigated through a series of statistically driven design of experiments (DOEs). A growing number of new ion mobility spectrometry (IMS) and ITMS applications are being performed with a physiological sample matrix, which is vastly different from the particulate and vapor matrixes that have been traditionally analyzed. Currently, there have been no efforts to globally examine the possibility of matrix suppression or enhancement of the IMS signal by these various components within physiological matrixes. This investigation consists of an effort to gauge the effects of common physiological buffer components and concentrations on two analytes of interest for ITMS analysis: o-nitrophenol and ephedrine. We show that, among the factors investigated, for a specific analyte and instrumental detection mode (i.e., negative/positive) the solution pH, presence of a protein, the buffer identity, and buffer concentration should be considered as they will enhance or suppress the ITMS signal while factors such as surfactant and salt concentration may play less of a role in impacting detectable ITMS signal. These observations are supported through statistical analysis of the DOE-derived data set.