Determination of Metalaxyl in Potatoes and Soil by Dispersive Solid-Phase Extraction and High-Performance Liquid Chromatography

A simple and sensitive high-performance liquid chromatography method with photodiode array detection combined with dispersive solid-phase extraction was developed to quantify metalaxyl residues in potatoes and soil. The limits of detection and quantification of metalaxyl were 0.0015 and 0.005mgkg(-1). The recoveries of metalaxyl extracted from potato, potato foliage, and soil ranged from 81.53-95.50%, 90.12-94.72%, 93.16-103.0%, respectively, with relative standard deviations less than 9.74%. The method was applied to determine metalaxyl in potatoes and soil; the results showed that the dissipation rates were described by first-order kinetics. The half-lives in potato foliage and soil were 0.75 days and 5.87 days to 8.45 days, respectively. At harvest, the residue of metalaxyl in potatoes was less than 0.05mgkg(-1) following the recommended dosage at an interval of seven days from the final application. These results may be used to help establish appropriate application frequencies and harvest intervals for metalaxyl on potatoes.