Improved detection of acephate residues in tomatoes using PSI-MS/MS with functionalized polyacrylamide modified substrate.

The increasing use of pesticides in agriculture has significantly improved crop quality and yield; however, concerns regarding their toxicity and environmental impact remain pressing. Acephate (ACE), an organophosphorus insecticide widely used in tomato cultivation, has been associated with various health risks, including neurotoxicity, reproductive toxicity, and metabolic disorders. Traditional methods for ACE detection, such as gas and liquid chromatography coupled with mass spectrometry (MS), offer high sensitivity and specificity but are time-consuming, solvent-intensive, and unsuitable for rapid on-site analysis. In this context, ambient ionization mass spectrometry (AIMS) has emerged as a promising alternative, enabling direct analysis with minimal sample preparation. Paper spray ionization mass spectrometry (PSI-MS) stands out as an effective AIMS technique, offering rapid, low-cost pesticide residue analysis compared to traditional chromatographic systems. However, unmodified chromatographic paper lacks selectivity for diverse analytes. To enhance ACE detection, this study introduces a novel PSI-MS substrate modified with polyhydroxamicalkanoate (PHA), a polyacrylamide functionalized with hydroxamic and carboxylic acid groups. This functionalized paper improves ionization efficiency and sensitivity for ACE analysis in tomato samples. The successful functionalization of the polyacrylamide polymer was confirmed through PHA characterization, ensuring its suitability for analysis. The proposed optimized method enables a rapid analysis time of just 3 min, demonstrating excellent linearity, precision, and accuracy. It also achieved low limits of detection and quantification, at 0.24 and 13.25 μg/kg, respectively, providing an innovative and efficient approach for pesticide residue determination in food matrices. ACE was detected in commercially available tomatoes, revealing regulatory non-compliance despite its prohibition under Brazilian legislation.