GC/MS studies on revealing products and reaction mechanism of photodegradation of pesticides

The photolytic degradation of frequently applied s-triazine type pesticides was investigated. A special, immersible UV-light source was applied in order to carry out photodegradation. The degradation processes were followed by TLC, GC and GC/MS techniques. Following the irradiation of the sample, the degradation products were isolated by SPE column chromatography. EI mass spectrometry was used to identify the degradation species.All four of the different s-triazine type pesticides studied underwent photolytic decomposition. The kinetic aspect of photodegradation of prometryn, terbutryn, simazine and atrazine was revealed completely, while in case of prometryn and terbutryn a detailed mechanism of photolytic transformation was established. Four degradation species were detected, as a consequence of two parallel ways of degradation. Both pesticides suffered the loss of thio-methyl groups prior to cleavage of the alkyl groups. Deamination did not occur under the conditions applied. The kinetic behaviour with respect to photodegradation displayed significant differences when comparing the decomposition of s-triazine type pesticides: prometryn decomposed 10 times faster than terbutryn.