Sensitive SPE GC-MS-SIM screening of endocrine-disrupting herbicides and related degradation products in natural surface waters and robustness study

This paper describes a very sensitive capillary gas chromatographic mass spectrometric selective ion monitored method for the simultaneous determination of three chloro-s-triazine herbicides, Atrazine (AT), Simazine (SI) and Propazine (PP), three thiomethyl-s-triazine ones: Ametryn (AM), Prometryn (PM) and Terbutryne (TB) and three chloro-s-triazine degradation products, Deethyl-atrazine (DEA), Deisopropyl-atrazine (DIA) and Deethyldeisopropyl-atrazine (DD) with herbicide activity too. The instrumental parameters affecting GC separation and MS/SIM detection were investigated and from this study the best conditions were selected. A previous extraction and preconcentration step was applied by means of an off-line solid phase extraction process getting so an enrichment factor of 104. The analytical performance characteristics of our method (stability, precision, linearity, LODs, LOQs, accuracy and robustness) were evaluated by means of a validation study on tap and deionised water samples using di-phenyl amide (DPA) as internal standard to achieve quantification. Natural water samples from different locations suspected to contamination were analysed by this off line SPE-GC-MS-SIM procedure and the results were also confirmed by an HPLC method.