ABSTRACT
Another interesting work was conducted by Minnard and coworkers [24]. The aim of this study was to test the feasibility of online sample pretreatment and separation on a single short-column LC-MS-MS using a thermospray interface. The authors also intended to demonstrate that by reducing the column length and by combining the SPE and the trace-enrichment steps with the analytical separation step onto such a single short column, it was possible to reduce the analysis time. They use triazine and phenylurea herbicides and they verified the method on surface water collected from a river. Two different columns, a classic C18 and a PLRP-S (a Styrene-divinyl benzene co-polymer) column, were employed in order to achieve better concentration detection limits. Chromatographic separation performed isocratically or with a steep gradient in short times (5 min) with the C18; using PLRP-S, it was not possible to elute all herbicides isocratically, so it was necessary to use a gradient from 40% to 95% methanol. The TSP interface was operated at a vaporizer temperature that varied between 75°C and 95°C; detection was carried out in the PI mode with filament-on and full-scan MS was performed with quadrupole 3 (Q3) scanned from mjz 175 to 300 in 0.45 s. The conclusions were that the PLRP-S column showed better stability than C18• It was possible, to improve the concentration detection limit from
