Simultaneous determination of triazines and their main transformation products in surface and urban wastewater by ultra-high-pressure liquid chromatography–tandem mass spectrometry

Abstract

This work describes the optimization, validation and application to real samples of an ultra-high-pressure liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) method for the quantification and confirmation of 11 compounds (atrazine, simazine, terbuthylazine, terbumeton, terbutryn and their main transformation products) in surface and wastewater samples. Most of these analytes are included in the list of priority substances in the framework on European Water Policy. The application of this method to water samples reveals that the most relevant transformation products (TPs) should be incorporated into current analytical methods (which are focused mainly on the determination of unchanged compounds), to obtain a more realistic knowledge on water quality regarding pesticide contamination. TPs are generally more polar and mobile than the parents and they can be transported to the aquatic environment more rapidly than their precursors. Additionally, they can present some degree of toxicity and in fact TPs are also included within the legislation on drinking water as pesticide derivatives.To efficiently combine UHPLC with MS/MS, a fast-acquisition triple quadrupole mass analyzer was used.Working in selected reaction monitoring mode, up to three simultaneous transitions per compound were acquired allowing a reliable identification at ng/L levels. The method developed includes a pre-concentration step based on solid-phase extraction (OASIS HLB cartridges). Satisfactory recoveries (70-120%) and relative standard deviations (<20%) were obtained for all compounds in different water samples types spiked at two concentration levels (0.025 and 0.1 µg/L). The optimized method was found to have excellent sensitivity with instrumental detection limits as low as 50 fg.In addition, the influences of the matrix constituents on ionization efficiency and extraction recovery have been studied in different types of Italian and Spanish surface and urban wastewater. Signal suppressions were observed for all compounds, especially for influent wastewater. The use of isotope-labelled internal standards was found to be the best approach to assure an accurate quantification in all matrix samples.

Monitoring a large number of pesticides and transformation products in water samples from Spain and Italy

“…The results of the present study in EWW from Spain were in line with other studies, where triazines, carbendazim, thiabendazole, diazinon and/or imidacloprid were also identified (BarcoBonilla et al, 2013a(BarcoBonilla et al, , 2013bBenvenuto et al, 2010;Masia et al, 2013). The carbamate insecticide carbaryl was detected only in one EWW sample, but it was not investigated in other studies.…”

“…Deethyl terbutylazine and deethyl terbumeton were detected in EWW (Benvenuto et al, 2010). The same compounds were identified in the present study and were the only ones identified in IWW and EWW.…”

“…These compounds were detected in almost all studies at different concentrations and frequency of detection (Benvenuto et al, 2010;Herrero-Hernandez et al, 2013;Pitarch et al, 2016;Robles-Molina et al, 2014). Some of these classes of pesticides and TPs were also identified in the present work.…”

“…Since then, terbutylazine and its TP, deethyl terbutylazine, have been detected at high frequency and in some cases the concentrations exceeded the EU limits (Bottoni et al, 2013). Other triazines detected in Italian SW were atrazine, simazine, atrazine desethyl, desisopropyl atrazine and terbutryn, but the concentrations were very low (a few ng/L) (Benvenuto et al, 2010;Bono and Magi, 2013;Bottoni et al, 2013;De Liguoro et al, 2014).…”

“…prochloraz) (Campo et al, 2013). Benvenuto et al (2010) examined triazines and their TPs in IWW, and terbutryn and 2-hydroxyterbutylazine were quantified in all the samples.…”