Simultaneous determination of four active ingredients of dinocap in crops by high-performance liquid chromatography

Analytical method for the determination of meptyldinocap as the 2,4-dinitro-octylphenol metabolite in cucumber and soil using LC-MS/MS and a study of the residues in a Chinese cucumber field ecosystem

BACKGROUND

Meptyldinocap (2,4-DNOPC) is a novel powdery mildew (Erysiphe necator) fungicide which shows protectant and post-infective activities. However, there is no reliable validated LC-MS/MS method for measuring trace levels of meptyldinocap in cucumber. A method for the determination of 2,4-DNOPC using LC-MS/MS in cucumber and soil was developed. Additionally, the mode of degradation and the residue levels in cucumbers and soils were investigated.

RESULTS

Recoveries of meptyldinocap from cucumber and soil samples were found to be 81.4-95.1%. The limits of quantification were found to be 0.01 mg kg(-1) in cucumber and soil. The half-lives of metpyldinocap in cucumbers and soils were in the ranges of 1.6 to 2.2 days and 3.1 to 4.4 days. The harvest residue levels of meptyldinocap in cucumbers and soils were in the ranges of below 0.01 mg kg(-1) to 0.92 mg kg(-1) , and below 0.01 mg kg(-1) to 0.53 mg kg(-1) . 5 days after application; the harvest residue levels of meptyldinocap in cucumbers in all treatments were below 0.1 mg kg(-1) .

CONCLUSION

Compared with the MRL for meptyldinocap in cucumber (0.1 mg kg(-1) ), set by the EU, it is suggested that there should be a pre-harvest interval of 5 days at the recommended rate and times before harvest of cucumber.

Analytical method validation for the determination of meptyldinocap as 2,4-dinitrooctylphenol metabolite in mango and soil using LC-MS/MS and dissipation study of the fungicide in Indian mango field ecosystem

An analytical method for the quantitative determination of meptyldinocap (2,4-DNOPC) as 2,4-dinitrooctylphenyl (2,4-DNOP) in mango and soil was developed as well as validated using liquid chromatography tandem mass spectrometry (LC-MS/MS). The method comprised an extraction with an acetone:methanol:4 N HCl (100:10:5, v/v/v) mixture followed by hydrolytic conversion of parent 2,4-DNOPC to the corresponding phenol metabolite (2,4-DNOP), and cleanup was done by liquid:liquid partition using ethyl acetate. Final quantitation was performed by LC-MS/MS of 2,4-DNOP with negative electrospray ionization using gradient elution. The method was validated at concentrations ranging from 0.025 to 2 μg/g, and the limit of quantification (LOQ) of meptyldinocap in mango and soil samples was 0.025 μg/g. The recovery of meptyldinocap from mango and soil sample was found to be 93-98% spiked at different levels with analyte, and the relative standard deviation for repeatability (RSD(r)) and reproducibility (RSD(R)) were acceptable (2-6%). The method was rugged as evident from a low measurement uncertainty at 0.05 μg/g. In order to evaluate its safety use in India a multilocational field dissipation study on meptyldinocap in mango was conducted by following the proposed analytical method.