Supercritical fluid chromatography coupled to tandem mass spectrometry for the analysis of pesticide residues in dried spices. Benefits and drawbacks.

This study describes the high sensitivity and the reduced ion suppression and matrix effect that can be achieved by supercritical fluid chromatography (SFC) in the analysis of dried spices as complex matrices. Samples selected for the evaluation were cayenne and black pepper, which are representative of complex dried spices. To carry out the evaluation of this technique, blank samples were fortified with a solution containing 162 pesticides at two concentration levels (50 and 200 μg kg-1). During the modified QuEChERS method, EMR sorbent was used as dispersive SPE in the clean-up step. The samples were analysed by supercritical fluid chromatography coupled to tandem mass spectrometry. The validation parameters studied were recovery, inter and intraday precision, linearity and matrix effect. Recoveries for the majority of compounds were in the 70-120% range recommended by DG-SANTE guidelines and showed a precision lower than 20% in terms of RSD. Matrix effect was low (0-20% signal suppression) for 132 pesticides in cayenne and 91 in black pepper. The method was used to analyse 47 real samples of spices from different countries. A high number of these samples presented one or more pesticides (81%). Some of these detected pesticides are not approved in the European Union and, in many cases, the positive findings exposed concentrations that exceed the EU MRLs.