Guidelines for the validation of qualitative multi-residue methods used to detect pesticides in food

• Published in: Drug testing and analysis 2012-08, Vol.4 (S1), p.10-16
• Main Authors: Mol, H. G. J., Reynolds, S. L., Fussell, R. J., Štajnbaher, D.
• Format: Article
• Language: English
• Subjects: Chromatography, High Pressure Liquid - methods; food; Food Analysis - methods; Food Contamination - analysis; Fruit - chemistry; fruits; Gas Chromatography-Mass Spectrometry - methods; gas-chromatography; Limit of Detection; liquid-chromatography; Mass Spectrometry - methods; mass-spectrometric detection; method validation; multi-residue methods; Pesticide Residues - analysis; pesticides; Pesticides - analysis; qualitative; Reproducibility of Results; vegetables; Vegetables - chemistry
• ISSN: 1942-7603; 1942-7611
• DOI: 10.1002/dta.1364

There is a current trend for many laboratories to develop and use qualitative gas chromatography–mass spectrometry (GC‐MS) and liquid chromatography‐mass spectrometry (LC‐MS) based multi‐residue methods (MRMs) in order to greatly increase the number of pesticides that they can target. Before these qualitative MRMs can be used for the monitoring of pesticide residues in food, their fitness‐for‐purpose needs to be established by initial method validation. This paper sets out to assess the performances of two such qualitative MRMs against a set of parameters and criteria that might be suitable for their effective validation. As expected, the ease of detection was often dependent on the particular pesticide/commodity combinations that were targeted, especially at the lowest concentrations tested (0.01 mg/kg). The two examples also clearly demonstrated that the percentage of pesticides detected was dependent on many factors, but particularly on the capabilities of the automated software/library packages and the parameters and threshold settings selected for operation. Another very important consideration was the condition of chromatographic system and detector at the time of analysis. If the system was relatively clean, then the detection rate was much higher than if it had become contaminated over time from previous injections of sample extracts. The parameters and criteria suggested for method validation of qualitative MRMs are aimed at achieving a 95% confidence level of pesticide detection. However, the presence of any pesticide that is ‘detected’ will need subsequent analysis for quantification and, depending on the qualitative method used, further evidence of identity. © 2012 John Wiley & Sons, Ltd. There is a current trend to use qualitative multi‐residue methods (MRMs) for the detection of pesticide residues in food based on gas chromatography‐mass spectrometry (GC‐MS) and liquid chromatography‐mass spectrometry (LC‐MS). This paper sets out to assess the performances of two such qualitative MRMs against a set of parameters and criteria that might be suitable for their effective validation. The most important factors influencing the effectiveness of the methods, in terms of their selectivity and sensitivity, are highlighted and discussed.