Application of Automated Mini-Solid-Phase Extraction Cleanup for the Analysis of Pesticides in Complex Spice Matrixes...

Pesticide residues are routinely tested in spices for trade compliance. This results in a huge sample load for food testing laboratories and demands automation in sample preparation. Although there exists a method for the analysis of pesticides in fruits using an automated sample cleanup by mini-solid-phase extraction (mini-SPE) technique, no study is available to date on spices.

This study aims to develop an automated sample cleanup method using mini-SPE technique in a range of spices, including chili powder, turmeric, black pepper, cumin, coriander, and cardamom.

This automated sample preparation workflow involved an X-Y-Z instrument autosampler, and a set of mini-SPE cartridges comprising cleanup sorbents. Spice samples were extracted by acetonitrile, and the extract was put into an autosampler vial for automated mini-SPE cleanup before analysis by GC tandem MS. For an efficient cleanup, three different sorbent compositions were compared along with various automated workflows.

For the relatively simple matrixes (e.g., coriander, cumin, and cardamom), the LOQ for the target pesticides was 10 ng/g with acceptable recovery, and precision. The method provided an LOQ of 10 ng/g for around 77% of the compounds in the relatively complex matrixes (e.g., turmeric, chili powder, and black pepper). The remainder of the compounds had satisfactory recoveries at 20 ng/g and higher levels.

Given its time effectiveness and efficient analytical performance, this method can be adopted in commercial food testing laboratories for time-bound analysis of a large volume of samples.

The study describes effectiveness of the automated mini-SPE cleanup in multiresidue analysis of pesticides in a range of spice matrixes. The method facilitates high-throughput residue analysis in compliance with the regulatory requirements of sensitivity and method performance.