Detection and analysis of nitrogen-containing pesticides in environment by surface-ionization methods

The results of a study of the possibilities of surface-ionization mass spectrometry (SI/MS) and atmospheric-pressure thermodesorption surface-ionization spectroscopy (APTDSIS) for high-sensitivity and selective detection and identification of nitrogen-containing pesticides are presented for some trisubstituted 1,3,5-triazines (prometryne, atrazine) and aromatic amines (trifluralin). An oxidized W band in vacuum (SI/MS) and oxidized Mo crystals doped with Ir in air (APTDSIS) were used as ion emitters. The SI mass spectra of pesticides have a small number of lines and consist of the ion lines (M + H) + , M + , (M - H) + and (M - R) + , being the products of chemical reactions in the adlayer (M is the molecule; H is the hydrogen atom; R is the radical). The herbicide molecules are ionized by SI with high efficiency. The APTDSIS spectra of pesticides have two characteristic maxima connected with energy of sublimation and desorption. The SI efficiency increases in the order 2.5,35 and 72 C/mol for trifluralin, atrazine, prometryne, respectively, and is within the linear range of the concentration dependence of 2-4 orders of magnitude. The results obtained by the SI/MS and APTDSIS methods have been compared with those obtained by GC/MS with electron ionization.