New practical approach for using an analyte protectant for priming in routine gas chromatographic analysis

A new practical approach of using an analyte protectant (AP) for priming a gas chromatography (GC) system has been investigated for routine pesticide residue analysis. Matrix co-extractives are known to cause signal improvement, called the “matrix-induced chromatographic response enhancement effect”. APs are known to provide advantages of signal enhancement independent of the matrix, but it takes time in routine applications to follow the common approach of adding APs to every extract. It is faster and easier to compensate for matrix effects by injecting an AP solution to coat active sites in the GC system at the beginning of the analytical sequence. In this study, 100 pesticides in highly pigmented QuEChERS extracts of chili were evaluated in the AP priming approach using GC–tandem mass spectrometry (MS/MS) over the course of many injections. The AP priming approach presented significantly more consistent results (87% of pesticides met RSD criteria) compared with injection sequences without the use of APs (42% of pesticides met RSD criteria). Also, AP priming with 300 ng d-sorbitol was found to display a similar trend to mixed AP in priming effect. We demonstrated that this approach is fit-for-purpose in routine analysis.