3. Results and discussion
3.1. General remarks on mass spectrometry
Preliminary evaluations were carried out using a 10 mg ml solution of each pesticide in the flow injection analysis (FIA) mode, and data were acquired in the scan mode (ca. m/z 100–400). The fragmentor voltage was adjusted to obtain the best compromise between enough fragmentation for identification purposes and sensitivity.
The fragmentor voltage was varied between 10 and 130 V. For the compounds studied the fragmentor has more influence on sensitivity than on the fragmentation pattern. Fig. 1 shows the mass spectra of the selected fungicides at 70 V fragmentor voltage, which was selected for the analytical procedure. The only ion obtained for dichloran and o-phenylphenol at any fragmentor voltage was the deprotonated molecule [M2H] (see Fig. 1). Flutriafol gave a molecular ion [M2H] and a fragment at m/z 204 that can be interpreted as [M2C6H6F2H] . The deprotonated molecule disappeared at fragmentor voltages higher than 90 V. The prochloraz spectrum presents two predominant fragments at m/z 356 and 196 that can be elucidated as [M2Cl1O] and [C H Cl O] , respectively. The molecular ion [M2H] was also observed with low intensity. Tolclofos methyl produced the main fragments at m/z 285 and 219 corresponding to [M2CH ] and [M2Cl1O2(OCH ) ] , respectively. Moreover characteristic fragment ions at m/z 255 and 175 were observed with low abundance.