DETERMINATION OF CHLOROTRIAZINES AND THEIR PHOTOLYSIS PRODUCTS BY LIQUID-CHROMATOGRAPHY WITH PHOTODIODE-ARRAY AND THERMOSPRAY MASS-SPECTROMETRIC DETECTION

Liquid chromatography with diode-array (LC-DA) and positive ion (PI) mode thermospray LC-mass spectrometry (LC-MS) were used for the determination of atrazine, cyanazine, simazine, deethylatrazine and deisopropylatrazine and their photolysis products. The LC analyses were performed on RP-18 columns using methanol-water (70:30) or methanol-water (70:30) + 0.05 M ammonium formate for LC-DA or LC-MS, respectively. The main degradation products observed after photolysis experiments with the suntest apparatus at 44°C were the corresponding hydroxytriazines, which could easily be differentiated from their parent compounds by the structured and distinctive UV spectral information given by LC-DA. The degradation rates after 5 h of irradiation varied from atrazine, deethylatrazine and deisopropylatrazine, which rapidily disappeared, to cyanazine and simazine, with 22 and 36%, respectively, remaining. Special emphasis was devoted to the characterization of the different photolysis products. By employing PI mode thermospray LC-MS, the identification of several photodegradation products such as the hydroxy, 2-H and 2-methoxy analogues was feasible, showing the [M + H]+ ion as the base peak and a second abundant ion corresponding to [M + CH3OH + H]+. The combined approach allows the identification directly after the photolysis experiments of the different solutions containing chlorotriazines, which is a clear advantage over current methods that require isolation of the photolysis products and elimination of water prior to MS characterization. © 1990.