The Residue Behavior Of Carbendazim And Triadimefon In White Paeony, Large-Head Atractylodes And Cultivated Soil

A simple, rapid residue analytical method of carbendazim and triadimefon in White paeony , Large-head Atractylodes and their cultivated soil was developed. The residues of carbendazim were extracted from samples with a methanol and 0.2 M hydrochloric mixture (V:V=90:10), concentrated extracts, regulated the pH to 7.0-7.5 with 2.0 M NaOH, extracted three times with 40ml methylene dichloride and determined by HPLC with a ultraviolet absorption detector. The detectable limit of HPLC estimated for carbendazim is 0.05 ng, and the minimum detectable concentration is 0.0125 mg/kg. The fortified recoveries of carbendazim in analytical samples were in range of 77.6%～97.6%, with relative standard deviations of 1.14～3.24%.The residues of triadimefon were extracted from samples with acetone ,the extracts were cleaned up by liquid-liquid extraction with dichloromethane and florisil column, determined by GC using capillary column equipped with a electron capture detector. The detectable limit of GC-ECD estimated for triadimefon is 0.01 ng, and the minimum detectable concentration is 0.0025 mg/kg. The fortified recoveries of triadimefon in analytical samples were in range of 78.9%～97.1%, with relative standard deviations of 1.17～2.90%.According to the result of residue test under the control condition of 30, 20,10℃, degrading speed of carbendazim and triadimefon in soil were related to the temperature. The higher the temperature was, the higher degrading speed was. The half lives of carbendazim in Xinwo soil were 7.22(30℃), 15.93(20℃), 22.35(10℃) days respectively. The half lives of triadimefon in Xinwo soil were 8.84(30℃), 11.00(20℃), 18.63(10℃) days respectively.Results of field test showed that the half lives of carbendazim were 4.51～6.50 days and 6.51～7.98 days in White paeony and cultivated soil, and were 5.02～7.01 days and 7.45～9.04 days in Large-head Atractylodes and cultivated soil respectively. The half lives of triadimefon were 5.16～7.87 days and 5.26～8.56 days in White paeony and cultivated soil, and were 6.00～7.53 days and 6.55～11.43 days in Large-head Atractylodes and cultivated soil respectively. It is 30 days that the carbendazim residue in White paeony was degraded below 0.1 mg/kg in two dosage (675 g a.i./hm~2 and 1000 g a.i./hm~2) treated trials, and below 0.2 mg/kg in Large-head Atractylodes. It is 30 days that the triadimefon residue was degraded below 0.1 mg/kg in 60 g a.i./hm~2 treated trials. But the residues of triadimefon in Large-head Atractylodes (Baizhu town) were 0.1319 mg/kg in 60 g a.i./hm~2 treated trials. If 0.3mg/kg is recommended as the MRL of carbendazim in White paeony and Large-head Atractylodes, and 0.2 mg/kg as the MRL of carbendazim in White paeony and Large-head Atractylodes, the pre-harvest interval (PHI) of carbendazim in White paeony and Large-head Atractylodes is 21 days for the 675 g a.i./hm~2 treatment, and PHI of triadimefon is 30 days for the 60 g a.i./hm~2 treatment, respectively.