SURFACE-IONIZATION ORGANIC MASS-SPECTROMETRY OF S-TRIAZINE HERBICIDES

Surface ionization organic mass spectrometry (SIOMS) was applied to so me s-triazine herbicides (simazine, atrazine, simetryne, ametryne and prometryne) by using quadrupole mass spectrometry in which the thermal ion source has a rhenium oxide emitter. The mass spectra were interpr eted in a purely empirical way by means of evidence from previous inve stigations, and then compared with conventional electron impact ioniza tion techniques. Sensitivity and selectivity were also studied, demons trating that (i) these herbicides are efficiently surface ionized, (ii ) in the SI mass spectra all s-triazines exhibited the M+ molecular io n as the base peak with only relatively minor fragment species, with t he exception of prometryne, (iii) the experimental results rationalize d the high sensitivity of surface ionization detection (SID) in gas ch romatography (GC) for the herbicides examined and (iv) GC/SIOMS coupli ng can be used for the sensitive and selective detection of these herb icides in the water. An approach to the detection of these herbicides in water by GC/SIOMS and GC/SID is described. The characteristics of b oth methods provide a reliable, sensitive and selective method which i s needed for low concentration level measurements in complex mixtures. (C) 1997 by John Wiley & Sons, Ltd.