State Key Laboratory Breeding Base of Green Pesticide and Agricultural Bioengineering, Key Laboratory of Green Pesticide and Agricultural Bioengineering, Ministry of Education, Guizhou University, Guiyang 550025, P. R. China.
J Agric Food Chem. 2021 Jan 13;69(1):501-510. doi: 10.1021/acs.jafc.0c05938. Epub 2021 Jan 4.
Four difenoconazole stereoisomers were well separated on a Superchiral S-OX column. The absolute configurations of the four stereoisomers of difenoconazole eluted in an orderly fashion with the chiral column were confirmed as (2,4), (2,4), (2,4), and (2,4)-difenoconazole, respectively, by single-crystal X-ray diffraction. For the first time, a simple and efficient trace detection method for the determination of residues of the four stereoisomers of difenoconazole in a plant sample by HPLC-MS/MS was developed. The mean recoveries were 78.23-104.38% with RSDs of 0.33-9.95%. The limits of detection for the four difenoconazole enantiomers were 0.0002-0.0004 mg/kg, and the limits of quantitation were 0.0044-0.011 mg/kg in citrus leaves and whole fruits. There was no obvious enantioselectivity upon degradation of the four stereoisomers in citrus leaves and whole fruits in Hunan and Guizhou. In Guangzhou, the rate of degradation of (2,4)-difenoconazole was the slowest among the four stereoisomers of difenoconazole.
四种联苯菊酯对映异构体在 Superchiral S-OX 柱上得到了很好的分离。通过单晶 X 射线衍射，确定了在手性柱上依次洗脱的四种联苯菊酯对映异构体的绝对构型分别为（2,4）、（2,4）、（2,4）和（2,4）-联苯菊酯。首次建立了一种简单、高效的高效液相色谱-串联质谱法测定植物样品中联苯菊酯四种对映异构体残留量的痕量检测方法。平均回收率为 78.23%-104.38%，相对标准偏差为 0.33%-9.95%。四种联苯菊酯对映异构体在柑橘叶片和全果中的检出限为 0.0002-0.0004mg/kg，定量限为 0.0044-0.011mg/kg。在湖南和贵州，四种联苯菊酯对映异构体在柑橘叶片和全果中的降解没有明显的对映体选择性。在广州，四种联苯菊酯对映异构体中（2,4）-联苯菊酯的降解速度最慢。
