Detection of pyridaben residue levels in hot pepper fruit and leaves by liquid chromatography–tandem mass spectrometry: effect of household processes

Zhao

et al. 2018

The present study investigates the occurrence of pymetrozine residues in cauliflower samples obtained from six cauliflower‐producing areas of China during fixed time periods in 2017 and estimates the dietary risk of pymetrozine in cauliflower. A liquid chromatography with tandem mass spectrometry method was developed and validated to detect pymetrozine in cauliflower. The samples were extracted using 20 mL of acetonitrile and purified with dispersive solid‐phase extraction using C18 as sorbent. The limit of quantification of pymetrozine was 0.008 mg/kg in cauliflower. The recoveries of the analyte were 82.04–95.18% with RSD <8.45%. The calibration curves for pymetrozine showed good linearities in the concentration range 0.004–2.0 mg/L with determination coefficients (R2) >0.999. Pymetrozine dissipated rapidly in cauliflower with a half‐life of <4 days. The terminal residues of pymetrozine were <0.008–0.0881 mg/kg in cauliflower at 7, 10 and 14 days after spraying from six sites. The routine washing process removed about half amount of the pymetrozine in cauliflower; the reduction ratios were 51.0–52.8%. The dietary risk assessment indicated that pymetrozine did not exhibit obvious dietary health risks in cauliflower when good agricultural practices were implemented.

Section: Resultsmentioning

confidence: 99%

Monitoring residue levels and dietary risk assessment of pymetrozine for Chinese consumption of cauliflower

Jia

Zhao

et al. 2018

“…Processing factor (PF) was used to evaluate the change of dimethachlon concentration in rice. The PF is the ratio between residue concentration (mg/kg) in processed food and residue concentration (mg/kg) in an unprocessed commodity (Kim et al, ). As could be seen, dimethachlon residue levels were reduced in rice after being processed into polished rice, the reduction ratios were 36.3–38.5% and the PFs were 0.615–0.637.…”

Section: Resultsmentioning

confidence: 99%

Residual level of dimethachlon in rice‐paddy field system and cooked rice determined by gas chromatography with electron capture detector

Sun

Zhong

et al. 2018

In this study, a modified quick, easy, cheap, effective, rugged and safe method coupled with gas chromatography with electron capture detection was established to determine dimethachlon residues in paddy soil, rice husk, rice straw, brown rice and cooked rice. The limits of quantification of dimethachlon were 0.01 mg/kg for paddy soil, brown rice and cooked rice and 0.02 mg/kg for rice straw and rice husk. The mean recoveries were in the range 78.59-104.7% with relative standard deviation values of <10% for dimethachlon in the five matrices. For field experiments, the final residues of dimethachlon in paddy soil were < 0.05 mg/kg and were < 1.21 mg/kg in rice straw from six sites. The final residues of dimethachlon in the brown rice at 21, 28 and 35 days after spraying from six sites were 0.08-7.58 mg/kg, and 0.16-30.1 mg/kg in rice husk. Our six test sites covered the main rice-producing areas of China. The routine rice cooking process of a Chinese family could apparently increase the removal of dimethachlon in rice compared with brown rice, and the reduction ratios were > 96%.

“…The method is also environmentally friendly because of its lower consumption of organic solvents, which is in agreement with the new trends in green analytical chemistry. Many studies have reported various modified QuEChERS methods to determine pesticide residues in peppers (Jang et al ., ; Zhu et al ., ; Rajski et al ., ; Kim et al ., ; Morales et al ., ; Mezcua et al ., ). Jang reported an analytical method for the analysis of etoxazole in red pepper using gas chromatography coupled with a nitrogen–phosphorus detector, which involved the application of a modified QuEChERS procedure (Jang et al ., ).…”

Section: Introductionmentioning

confidence: 99%

Multiresidue determination of pyrethroid pesticide residues in pepper through a modified QuEChERS method and gas chromatography with electron capture detection

Zhang

et al. 2015

This study developed and used a modified quick, easy, cheap, efficient, rugged and safe (QuEChERS) method coupled with gas chromatography with electron capture detection to determine eight pyrethroid pesticide residues in green, red and dehydrated red peppers. Pyrethroids were extracted with acetonitrile, partitioned with sodium chloride and purified with primary secondary amino and graphitized carbon black in hexane. The QuEChERS extraction conditions were optimized, and the matrix effects that might influence recoveries were evaluated and minimized using matrix-matched calibration curves. Under the optimized conditions, the calibration curves for pyrethroid pesticides showed good linearities in the concentration range of 0.05-20 µg/mL with determination coefficients (R(2) ) >0.997. The limits of quantification of eight pyrethroids were 0.004-0.04 mg/kg for green and red pepper and 0.04-0.5 mg/kg for dehydrated red pepper. These values are below the suggested regulatory maximum residue limits. The mean recoveries ranged between 79.0 and 104%, and the relative standard deviations were <11%. The developed method was successfully applied to commercial samples. Some samples were found to contain pyrethroid pesticides with levels below the legal limits.