Goal
To develop and test an IC-MS/MS multi-residue method that can be applied for high-throughput screening and quantitation of polar pesticide residues and their metabolites in food matrices below the current legislative requirements.
Introduction
The presence of very polar ionic pesticides in surface and drinking water, as well as food and beverages, has become a controversial issue in recent years. The development of genetically modified crops tolerant to glyphosate and glufosinate, for example, promoted the use of these broad spectrum herbicides.
In addition, glyphosate is used as a crop desiccant to suppress weeds in parks and at roadsides. Consequently, these pesticides often occur in foods as residues and in the environment as contaminants of surface waters. There are concerns about their potential adverse effects on human health, such as their potential carcinogenicity,1 although the latest toxicological assessments do not predict risks for humans under normal conditions or environmental exposures.2 Current regulations offset maximum residue levels (MRLs) of glyphosate and its metabolite aminomethylphosphonic acid (AMPA) at 100 ng/L in drinking water. In food and beverage samples, higher MRLs typically apply, ranging generally from 10 μg/kg for food intended for consumption by children up to hundreds of mg/kg in other matrices.3The analysis of glyphosate and other polar compounds presents a difficult analytical challenge. Their polarity does not allow the direct analysis by reversed-phase HPLC, so alternative methods need to be applied. Derivatization of glyphosate prior to analysis4 or application of specific chromatographic columns, such as the Thermo Scientific™ Hypercarb™ column, are the common approaches.5 With both of these approaches, poor method robustness and questionable results are often reported in laboratories, especially when the method is applied in routine high-throughput analysis of samples with rather complex matrix composition. Recent developments in ion chromatography and mass spectrometry offer many advantages for the analysis of very polar substances. Ion chromatography is the preferred separation technique for polar ionic analytes, such as anions, cations or small polar analytes (metabolites), and sugars. Mass spectrometry, namely in triple quadrupole MS/MS systems, offers very low detection limits and high detection selectivity when operated in selected reaction monitoring (SRM) mode. The system robustness allows the analysis of food and environmental samples.
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