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

Abstract

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.

Differential mobility spectrometry/mass spectrometry history, theory, design optimization, simulations, and applications

“…Significant development of DMS‐MS technology continued from this time in several laboratories that leveraged the expertise of the original Soviet developers now in North America (Nazarov et al, ,; Krylov, Nazarov, & Miller, ; Borsdorf, Nazarov, & Miller, ; Krylov & Nazarov, ; Nazarov, ,). Activities expanded into other groups outside this sphere of influence (Roetering et al, ; Borsdorf & Mayer, 2010; Spangler, ;). Notable efforts sprung up among new groups at the Pacific Northwest National Laboratories (PNNL) (Richland, WA) (Shvartsburg, Maskevich, & Smith, ; Shvartsburg & Smith, 2007, 2011a, 2013b; Shvartsburg, ; Shvartsburg, Danielson, & Smith, ; Shvartsburg, Tang, & Smith, ; Shvartsburg et al, ), University of Florida (Rorrer & Yost, 2011; Tsai, Yost, & Garrett, ), University of North Carolina (Ferzoco et al, ; Ridgeway, Remes, & Glish, ; Isenberg, Armistead, & Glish, ), and Northeastern University (Levin et al, ,, ; Hall et al, ,, ; Kafle et al, , ).…”

Analysis of gasoline contaminated water samples by means of dopant-assisted atmospheric pressure photoionization differential ion mobility spectrometry

“…The increase of APPI-DMS sensitivity in presence of dopant was previously demonstrated on examples of dimethyl methylphosphonate, [12] butanone, [12] and several pesticides [13]. Benzene is one of the dopants used in previous studies.…”

“…It was demonstrated that the addition of the appropriate amount of volatile organic compounds (dopants/modifiers) to the transport gas can significantly enhance the sensitivity of planar DMS with APPI ionization source [12,13]. Moreover, the increase of the resolving power of planar DMS in the presence of chemical modifiers was also demonstrated [14][15][16][17].…”

Non-polar modifier assisted analysis of aromatic compounds by means of planar differential ion mobility spectrometry with a 63Ni ionization source

“…Roetering et al have demonstrated that the utilization of traces of benzene (0.260 ppm v ) for the analysis of the pesticides with APPI-DMS results in both an improvement of the sensitivity of the method and a shi of the analyte peaks. 36 The increase in the sensitivity was explained by the increased ionization efficiency of analytes over the charge exchange with the photoionized benzene radical cation. Despite the differences in ionization mechanisms proposed for APPI (depends on the ionization potential) and 63 Ni-ionization-based (depends on proton affinity) sources, these ndings demonstrate the prospects for the utilization of aromatic modiers for the improvement of the peak separation in the differential ion mobility based methods.…”