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BACKGROUND Propiconazole is widely used to control fungal diseases in field crops, including celery and onion. The potential risk to the environment and human health has aroused much public concern. Therefore, it is significant to investigate the degradation behaviour, residue distribution, and dietary risk assessment of propiconazole in celery and onion. RESULTS: A sensitive analytical method for determination of propiconazole residue in celery and onion was established and validated through high‐performance liquid chromatography tandem mass spectrometry. The average recovery rate of propiconazole ranged from 85.7% to 101.8%, with a relative standard deviation of 2.1–6.3%. For the dissipation kinetics, the data showed that propiconazole in celery and onion was degraded, with half‐lives of 6.1–6.2 days and 8.7–8.8 days respectively. In the terminal residue experiments, the residues of propiconazole were below 4.66 mg kg−1 in celery after application two or three times and were below 0.029 mg kg−1 in onion after application of three or four times with an interval of 14 days under the designed dosages. The chronic and acute dietary exposure assessments for propiconazole were valued by risk quotient, with all values being lower than 100%. CONCLUSION: Propiconazole in celery and onion was rapidly degraded following first‐order kinetics models. The dietary risk of propiconazole through celery or onion was negligible to consumers. The study not only offers a valuable reference for reasonable usage of propiconazole on celery and onion, but also facilitates the establishment of maximum residue limits in China. © 2020 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

The dissipation and residue levels of thiacloprid, spirotetramat and its four metabolites residues in cowpeas were investigated under field conditions. The QuEChERS technique with high-performance liquid chromatography tandem mass spectrometry (HPLC–MS/MS) was used to detect thiacloprid, spirotetramat and its four metabolites residues content in cowpeas. The recoveries were 81.3–95.1% at a spike level of 0.005–0.5 mg/kg, the relative standard deviations (RSDs) were 2.1–9.5%. The dissipation kinetics data showed that thiacloprid and spirotetramat in cowpeas were degraded with the half-lives of 1.14–1.54 days and 1.25–2.79 days. The terminal residues of thiacloprid and spirotetramat were 0.0255–0.4570 mg kg−1 and 0.0314–0.3070 mg kg−1 after application 2 times with a pre-harvest interval (PHI) of 3 days under the designed dosages. The chronic and acute dietary exposure assessment risk quotient (RQ) values of thiacloprid in cowpeas for different consumers were 2.44–4.41% and 8.72–15.78%, respectively, and those of spirotetramat were 1.03–1.87% and 0.18–0.32%, respectively, all of the RQ values were lower than 100%. The dietary risk of thiacloprid through cowpeas to consumers was higher than spirotetramat. The results from this study are important reference for Chinese governments to develop criteria for the safe and rational use of thiacloprid and spirotetramat, setting maximum residue levels (MRLs), monitoring the quality safety of agricultural products and protecting consumer health. [ABSTRACT FROM AUTHOR]

Dissipation, residues and risk assessment of lufenuron during kumquat growing and kumquat processing were investigated under field and household conditions. The QuEChERS technique with high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) was used to detect lufenuron residues content in kumquats and its processed products. The recoveries were 82.3–102.8% at a spike level of 0.005–0.5 mg kg−1, the relative standard deviations (RSDs) were 1.1–9.4%. The dissipation kinetics data showed that lufenuron in kumquats were degraded with the half-lives of 9.12–12.60 days. The terminal residues of lufenuron in kumquats were 0.064–0.107 mg kg−1 after application one times with a pre-harvest interval (PHI) of 14 days under the designed dosages. The juicing process can significantly reduce the residues of lufenuron in kumquats juice, and the processing factor (PF) value of juicing process was 0.15. The chronic dietary exposure assessment risk quotient (RQ) values of lufenuron in kumquats fruit and juice for different consumers were 0.71–2.13% and 0.37–0.86%, all of the RQ values were lower than 100%. The results from this study are important reference for Chinese governments to develop criteria for the safe and rational use of lufenuron on kumquats and monitor the quality safety of agricultural products and protecting consumer health. • Residue behaviorof lufenuron in kumquats during growing and processing is reported for the first time. • The degradation half-life of lufenuron showed that lufenuron degrades relatively slowly. • The juicing process can significantly reduce the residues of lufenuron in kumquats juice. • Dietary exposure risks associated with lufenuron in kumquats fruit and juice in China are all not a health concern. [ABSTRACT FROM AUTHOR]