Comparison of different cleanup procedures for oil crops based on the development of a trace analytical method for the determination of pyraclostrobin and epoxiconazole

Abstract

The effects of different cleanup procedures in removing high-molecular-mass lipids and natural colorants from oil-crop extracts, including dispersive solid-phase extraction, low-temperature precipitation and gel permeation chromatography, were studied. The pigment removal, lipid quantity, and matrix effects of the three cleanup methods were evaluated. Results indicated that the gel permeation chromatography method is the most effective way to compare the dispersive solid-phase extraction and low-temperature precipitation. Pyraclostrobin and epoxiconazole applied extensively in oil-crop production were selected as typical pesticides to study and a trace analytical method was developed by gel permeation chromatography and ultra high performance liquid chromatography with tandem mass spectrometry. Average recoveries of the target pesticides at three levels (10, 50, and 100 μg/kg) were in the range of 74.7-96.8% with relative standard deviation values below 9.2%. The limits of detection did not exceed 0.46 μg/kg, whereas the limits of quantification were below 1.54 μg/kg and much lower than maximum residue limit in all matrices. This study may provide the essential data for optimizing the analytical method of pesticides in oil-crop samples.

Stereoselective determination of dufulin in watermelon under field conditions using chiral ultra high performance liquid chromatography with high‐resolution mass spectrometry

“…Dissipation dynamics were calculated from the first‐order rate equation, C t = C 0 e – kt , where C t is the concentration of the pesticide residue at time t , C 0 is the initial concentration, and k is the rate constant (days –1 ). The half‐life ( t 1/2 ) was calculated from the k value for each experiment ( t 1/2 = ln 2/ k ) . The dissipation dynamics of the two dufulin enantiomers in watermelon samples collected from Guizhou and Beijing were fitted with first‐order kinetics (Fig.…”

Effects of Planting and Processing Modes on the Degradation of Dithianon and Pyraclostrobin in Chinese Yam (Dioscorea spp.)

“…The combination of these two pesticides shows higher fungicidal activity and longer lifetimes than either alone . In previous studies, residues of dithianon and pyraclostrobin have been determined in various fruits, vegetables, and grain by high-performance liquid chromatography coupled with ultraviolet detector (HPLC-UV), high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS), and gas chromatography coupled with time-of-flight mass spectrometry (GC-TOFMS). − …”