Quantitative NMR for detection of spinosad residues in agricultural soils

Abstract

Monitoring pesticide residues in soil is crucial for ensuring food safety and environmental sustainability. Spinosad, widely used in sustainable agriculture due to its selective toxicity and reduced environmental impact, poses detection challenges with traditional chromatographic methods, which require extensive sample preparation and are destructive. This study evaluates quantitative nuclear magnetic resonance (qNMR) as a non-destructive, efficient method for spinosad quantification in soil samples, emphasizing its potential for routine environmental monitoring. The qNMR method was validated with an 88% recovery rate for spinosad in agricultural soils, a limit of detection (LOD) of 0.0414 mg mL⁻¹, and a limit of quantification (LOQ) of 0.1254 mg mL⁻¹. The method exhibited linearity across a 2–8 mg mL⁻¹ concentration range (R² = 0.9928) and high precision, with coefficients of variation below 1% for both intraday and interday analyses. It was adaptable to diverse soil types, achieving consistent quantification in red loamy soil from Veracruz and black organic soil from Querétaro, Mexico. These results establish qNMR as a reliable, cost-effective alternative to chromatographic methods for spinosad residue analysis in soil, supporting routine environmental monitoring and regulatory compliance in sustainable agriculture.