Effect of dopants on the analysis of pesticides by means of differential mobility spectrometry with atmospheric pressure photoionization

The chances to improve the detection of pesticides using differential mobility spectrometry (DMS) with an atmospheric pressure photoionization (APPI) ion source by means of dopants was investigated. The effect of employing benzene, anisole and chlorobenzene as dopants is described regarding sensitivity, limits of detection and peak displacements in the spectra. For typical pesticides an improvement of detection limits up to two orders of magnitude could be determined, while for the peak shift of individual substances no uniform behaviour was observed. Possible mechanisms of action in respect to atmospheric pressure photoionization (APPI) processes are discussed.