Residue and dissipation of pyraclostrobin by high performance liquid chromatography in tobacco and soil

A new method was developed to detect pyraclostrobin residues in tobacco and soil using HPLC with diode-array detector.Tobacco and soil samples were extracted with acetonitrile,cleaned up by Solid Phase Extraction Column(SPE) C18 and PSA columns and detected by High Performance Liquid Chromatography-Diode Array Detector(HPLC-DAD).Average recoveries of pyraclostrobin fortified at 0.01,0.2 and 2 mg/kg in tobacco leaves ranged from 97.5% to 101.9% and in soil from 93.4% to 101.2% with the relative standard deviations(RSD) of 4.8% to 6.8%,1.5% to 10.5%,respectively.The limit of quantity(LOQ) was 0.01 mg/kg in soil and tobacco leaves.Field experiments were performed in Qingdao,Shandong province and Changsha,Hu'nan province during 2011 to 2012.Using the above method,residue dissipation of pyraclostrobin in tobacco leaves and soil were detected.In Shandong province the results showed that,the half-lives of pyraclostrobin were 5.9-9.5 d in green tobacco leaves and 11.1-13.4 d in soil,respectively,whereas in Hu'nan province,the half-lives were 3.1-5.3 d in green tobacco leaves and 5.4-6.4 d in soil,respectively.