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.

A procedure based on the coupling of pulsed laser desorption and differential mobility spectrometry is described which allows the fast screening of surfaces in respect to organic contaminations, in particular pesticides. We investigated the general capability of this technique for the rapid screening of pesticides from fruit surfaces. Although the coupling presented requires further optimization, the method developed permits the fast detection of pesticides from the surfaces of apples, grapes, tomatoes and pepper in the ng range. The initial results regarding the detection and quantification of a few prominent pesticides on different materials are presented.