Goal
The aim of the study was to assess the quantitative performance of the Thermo Scientific™ TSQ™ 9000 triple quadrupole GC-MS/MS system fitted with the Advanced Electron Ionization (AEI) source for the analysis of pesticide residues at ultra low levels in baby food.
Introduction
The detection and subsequent quantification of pesticides, contaminants, and other chemical residues are of paramount importance, especially when the food stuff is intended to be consumed by infants or young children. The maximum residue level (MRL) for the majority of pesticide-commodity combinations is set at the default level of 10 μg/kg.1–3 However, the European Union (EU) has established LOD MRLs between 3–8 μg/kg for specific pesticides prohibited in baby foods.4 These pesticides and their metabolites may cause infants and young children (under worst-case intake conditions) to exceed the acceptable daily intake (ADI) values. The high sensitivity and selectivity of GC-MS/MS enables the detection and identification of residues of prohibited compounds, in compliance with the residue definitions, even when dealing with the diverse composition of multi-ingredient baby foods.
Also, the increased levels of selectivity and sensitivity provided by triple quadrupole instruments compared to single quadrupole instruments enabled analysts to adopt faster, less specific sample extraction procedures such as QuEChERS (quick, easy, cheap effective, rugged and safe). The QuEChERS procedure has become the standard approach for sample preparation in many laboratories because of improvement in productivity.5 The method usually involves extraction with acetonitrile in the presence of various salts followed by dispersive solid phase extraction (dSPE) clean-up with a combination of PSA, C18, and carbon sorbents. The efficiency of the dSPE clean-up is limited so high concentrations of matrix-coextractives can remain in the final extract and cause system contamination. Also, use of acetonitrile (which has a high coefficient of expansion) limits the injection volume and hence the sensitivity of the method.Taking all of these considerations together, it is evident that an ultra-sensitive, selective, reliable, and robust GC-MS/MS system is needed to address the challenge of routine high-throughput determination of pesticide residues at trace concentrations in baby foods. In this study, the quantitative performance of the Thermo Scientific™ TSQ™ 9000 triple quadrupole GC-MS/MS system was assessed for the analysis of more than 200 pesticides in baby food at ultra low concentrations (as low as 0.025 μg/kg). A complete evaluation of method performance included sample preparation, overall method suitability measured from pesticides recoveries, selectivity, sensitivity, linearity, and long-term robustness.
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