Solvent vapor effects on planar high-field asymmetric waveform ion mobility spectrometry

The effects of various concentrations of solvent vapor (either water or methanol) added to the curtain/drift gas in a planar high-field asymmetric waveform ion mobility spectrometer (FAIMS) have been examined. Two different groups of analyte ions (the [M-H](-) ions of three positional isomers of phthalic acid and the M- and [M-H](-) ions of four explosives: TNT, 2.4 DNT, 2.6 DNT, and 3.4 DNT) were analyzed. Results showed that with the addition of small amounts of solvent vapor (similar to 1.5% water and 12.3% methanol), there were dramatic shifts to larger CV values for all ions analyzed. There were substantial benefits provided by adding solvent vapor, including dramatically increased resolving power of isomeric ions (up to similar to 141). Specifically, analyte ions examined in dried nitrogen exhibited overlapping, undistinguishable CV values, but with large CV shifts afforded by addition of solvent vapor, these analyte ions were completely resolved from one another. (C) 2010 Elsevier B.V. All rights reserved.