Persistence of metalaxyl residues on tomato fruit using high performance liquid chromatography and QuEChERS methodology

Metalaxyl is a widely used fungicide around the world. Very limited data have been reported concerning the dissipation and residue of metalaxyl in agricultural products. Residues and dissipation rate of metalaxyl were estimated in tomato fruit by HPLC following single application of the fungicide at 262.5 g a.i. ha−1. The average initial deposit of metalaxyl on tomato fruits was found to be 2.39 mg kg−1. Residues of metalaxyl dissipated below the maximum residue limit (MRL) of 0.5 mg kg−1 in 7 days. Half-life (t1/2) for degradation of metalaxyl on tomato fruit was observed to be 1.81 days. A waiting period of 7 days is suggested for safe consumption of tomato. The results would be useful for the safe use of metalaxyl and to prevent any health problem to customers

Dissipation Profile and Human Risk Assessment of Pyrimethanil Residues in Cucumbers and Strawberries

Background. The present investigation was undertaken to study the persistence of pyrimethanil in strawberries and cucumbers following good agricultural practices under field conditions. A secondary objective was to validate a quick, easy, cheap, effective, rugged and safe (QuEChERS) method for the determination of pyrimethanil levels in strawberries and cucumbers using high performance liquid chromatography with photodiode array detection. Methods. Pyrimethanil (20% wettable power (WP)) was sprayed on strawberries and cucumbers grown under field conditions at the dosage recommended by the manufacturer. The dissipation rates of pyrimethanil were described using first-order kinetics and its half-life was 2.9 days in strawberries and 2.2 days in cucumbers. A risk assessment was performed using the risk quotient (RQ). Results. At fortification levels of 0.05, 0.1 and 0.5 mg/kg in strawberries and cucumbers, recoveries ranged from 90.1 to 109% with a relative standard deviation (RSD) ranging from 2.0–7.9%, which is within the acceptable limits for routine analysis of pyrimethanil residues. The limit of quantification (LOQ) was established at 0.05 mg/kg. The results showed that the RQ value was significantly lower than 1. Conclusions. The results of the present study suggest that the risk of pyrimethanil use in strawberries and cucumbers at the recommended dosage is negligible to humans. This study could provide guidance for the safe and reasonable use of pyrimethanil in strawberries and cucumbers to prevent health problems in consumers. Competing Interests. The authors declare no competing financial interests