Residue and dissipation dynamics of boscalid in strawberry and soil

Field experiments were conducted to study the residues and dissipation dynamics of boscalid in Chinese strawberry and soil in Shandong and Beijing for two years. The dispersive solid phase extraction combined with gas chromatography-mass spectrometry (GC-MS) method was established to determine the boscalid residue in strawberry and soil rapidly. The impact of different variety of agricultural products and environmental conditions on digestion rate were studied. The recoveries of boscalid in strawberry were 91%-121% with RSDs between 5.8% and 9.9% with spiking at 0.05, 0.3 and 3 mg/kg. The limit of quantitation (LOQ) of this method in strawberry samples was 0.05 mg/kg. The recoveries of boscalid in soil were 91%-100% with RSDs between 5.4% and 6.5% with spiking at 0.1, 0.3 and 3 mg/kg. The LOQ of this method in soil samples was 0.1 mg/kg, which could meet the requirement of max residue limits (MRLs) of boscalid. In decline study, the dissipation equations of boscalid in strawberry fit the pseudo-first-order reaction dynamic equations or the first-order reaction dynamic equations, and the half-lives of dissipation of boscalid were estimated to be 6.2 d and 11.8 d in strawberry. Boscalid was detected in soil samples from Shandong and Beijing, however, its dissipation dynamic equations did not fit the first-order reaction dynamic equation. The recommended dosage of 50% boscalid WG for control of grey mold in strawberry was 337.5 g/hm2, the drug may delivered no more than 3 times, each time should over 3 d interval. The maximum final residue of boscalid strawberry and soil were 1.97 mg/kg and 0.38 mg/kg, respectively.