Pesticide residues in spices and herbs: Sample preparation methods and determination by chromatographic techniques

Most widely developed approaches for pesticide residues analysis in spices and herbs present serious limitations; this is because of the high number of interferences that they typically contain, which makes it difficult to identify/quantify compounds in a considerable percentage of cases. Different strategies are applied to overcome these difficulties including extensive clean-up steps, dilution of the extracts, more selective detection techniques and other effective methods. However, there is a strong matrix effect present with the most complex matrices. Recent advances with new clean-up sorbents and the greater sensitivity and selectivity provided by modern mass spectrometers facilitates the determination of pesticide residues in these complex matrices at the desired limits of quantification. This review summarizes the main sample extraction and clean-up procedures for pesticide residues in spices and herbs published between 2008 and 2018, evaluating both their strengths and limitations. In addition, the high-end mass spectrometry detection methods are critically discussed.