草甘膦铵盐在苎麻田的残留及消解动态

建立了简单、灵敏的土壤及苎麻中草甘膦残留量的气相色谱检测方法。土壤样品用0.01 mol/L 的氢氧化钠水溶液提取,其他样品用水和丙酮提取,经阴离子交换柱(AG1-X8)净化,与原乙酸三甲酯(TMOA)和冰醋酸反应,用气相色谱带火焰光度检测器(FPD)检测,外标法定量。结果表明:当草甘膦在麻蔸和土壤中的添加水平在0.05~1 mg/kg时,添加回收率分别为 73.6%~102.6% 和85.9% ~105.1%,相对标准偏差分别为2.3% ~8.1% 和5.4% ~13.0%。草甘膦的最小检出量(LOD)为0.5×10-10 g,在麻蔸中的最低检测浓度(LOQ)为0.05 mg/kg。2年3地的残留试验结果表明:草甘膦铵盐在湖南省、广西壮族自治区及福建省土壤中的半衰期分别为1.6~2.6 d,1.0~1.8 d和1.1~1.5 d。无论是在高浓度处理区 还是在低浓度处理区 ,苎麻收获时(距施药60 d),土壤和麻蔸样品中均未检出草甘膦铵盐。

Residue and field decline study of glyphosate-ammoniumin ramie field

A simple,sensitive and selective method using gas chromatorgaphy equipped with flame photometric detector (GC-FPD) was developed to determine residues of glyphosate-ammonium in soil and ramie root.Soil samples were extracted with 0.01 mol/L sodium hydroxide and other samples were extracted with water and acetone.Glyphosate was previously derived with trimethylorthoacetate (TMOA) in the presence of acetic acid.Combination of AG1-X8 anion exchange chromatography with Florisil cartridge cleanup process was favorable for the GC-PFPD analysis.The recovery ranged from 73.6% to 102.6% and 85.9% to 105.1% with the relative standard deviations of 2.3% to 8.1% and 5.4% to 13.0%,respectively.The limit of detection (LOD) of the method was 0.5×10^-10 g.The limit of quantification (LOQ) was 0.05 mg/kg.The half-life of glyphosate-ammonium was 1.6-2.6 d,1.0-1.8 d and 1.1-1.5 d in soil of Hunan,Guangxi and Fujian Province at two years,respectively.No glyphosate-ammonium residues were detected in ramie and soil samples at treatments of 2 250-3 375 g(a.i.)/ha at harvest season (60 days after the treatment).