Assessing the feasibility of direct injection for pesticide residue analysis in grape juice by liquid chromatography/triple quadrupole mass spectrometry

In Brazil, the regulation of pesticide residues is guided by the National Health Surveillance Agency (ANVISA) and the Ministry of Agriculture and Livestock (MAPA), emphasizing the importance of monitoring pesticide levels in agricultural products to protect consumer health. High pesticide residue concentrations can compromise the organoleptic qualities and overall quality of the grape juice, in addition to being harmful to the consumer’s health, making residue analysis crucial. Traditional methods for pesticide analysis in grape juice and wine, like Solid Phase Extraction (SPE) and Dispersive Solid-phase Extraction (dSPE), are time-consuming and costly. An alternative approach, the Dilute-and-Shoot (DnS) technique, has been explored using Liquid Chromatography-Mass Spectrometry (LC-MS), but its robustness and reliability have not been thoroughly assessed. In this study, 71 pesticides were analyzed in grape juice using Liquid Chromatography-Triple Quadrupole Mass Spectrometry (LC/MS-MS) with a direct injection method, including 450 injections over 9 days. The results showed that direct injection with only a 50% dilution and filtration was effective, with stable peak intensities up to 350 injections, indicating the feasibility of this method without complex sample preparation. The study suggests that simple procedures can improve injection throughput, although factors like pre-column saturation and column wear need further investigation for optimization.