高效液相色谱法测定土壤中的二氯喹啉酸

用50 ml甲醇︰0.05 mol/L硼砂溶液(p H=10)(9︰1,v/v)作为提取剂对20 g(或适量)土壤样品中残留的二氯喹啉酸振荡提取2 h,离心过滤后分取滤液25 ml浓缩,甲醇定容至2 ml,再用滤膜过滤后待测定;高效液相色谱仪(HPLC)以1.0 ml/min的甲醇︰1%乙酸水溶液(55︰45,V/V)为流动相,柱温45℃,在238 nm的紫外光波长下进行二氯喹啉酸的外标法定量。该方法精密度为6.0%,检出限为0.012 mg/kg,不同类型土壤的加标回收率74.9%~98.8%,能满足有机分析要求。该方法既简捷易操作,又能满足土壤中二氯喹啉酸低残留量的测定。

Determination of Quinclorac in Soil Sampleswith High Performance Liquid Chromatography (HPLC)

Quinclorac is an effective herbicide commonly used in rice plantation. But Quinclorac residue in soil probably brings teratogenesis to some Quinclorac sensitive rotation crops, like Solanaceae plants, Leguminosae emblements. So the residue in soil should be accurately detected. Quinclorac residue in soil sample was extracted on a to-and-fro shaker for 2 hours with 50 ml extractant, which was the mixture of methanol and 0.05 mol/L borax solution (pH = 10) at the ration of 9︰1 (v/v). The extracts was centrifuged and subsequently filtered. 25 ml filtrate was concentrated to about 1 ml and then diluted to 2 ml with methanol for high performance liquid chromatography (HPLC) determination. Content of Quinclorac in extracts was calculated according to external standard method by HPLC under optimized condition. Briefly, 1.0 ml/min methanol: 1% (v/v) acetic acid solution (55︰45,v/v) was selected as mobile phase to elute the target compound for ultraviolet (UV) detection at 238 nm wavelength. The Quinclorac detection limit of this method was 0.012 mg/kg; the recovery rates of different type soil samples lingered in the scope of 74.9% – 98.8% with precision being 6.0% (n=6). All demonstrate that the method meets the requirements of organic analysis. The method is relatively simple and easy to operate. As well as it can be used to analyze the low concentration of Quinclorac residue in soil sample.