LASER-DESORPTION FOURIER-TRANSFORM ION-CYCLOTRON RESONANCE MASS-SPECTROMETRY OF SELECTED PESTICIDES EXTRACTED ON C-18 SILICA SOLID-PHASE EXTRACTION MEMBRANES

Laser desorption Fourier transform ion cyclotron resonance mass spectr ometry was coupled with solid-phase extraction (SPE) on Cls silica mem branes for the determination of selected pesticides in water, The deso rption process for hydroxyatrazine was demonstrated to take place at t he surface of the membrane, The method was further investigated using other model compounds, flumequine, isoproturon and flutriafol, These t hree pesticides have shown a different behaviour to hydroxyatrazine wh en extracted on SPE membranes, Among them, only flumequine was detecte d at 248 nm, The use of a 355 nm laser wavelength allowed the detectio n of all three compounds but under more vigorous conditions leading to significant fragmentation, The unexpected behaviour at 248 nm is not clearly explained by the respective UV absorptions of the molecules at the laser wavelength but would more likely depend on different intera ctions with the membrane.