随机选取代表性土壤样品约1 kg,四分法将土壤样品缩分,取约200 g风干、粉碎、过筛。取上述土壤样品10.0 g置于萃取池中,加入硅藻土15.0 g混合均匀后进行加速溶剂萃取(ASE),采用凝胶净化系统净化提取液。取净化液10 mL,于50 ℃氮吹至近干,残渣用1 mL甲醇溶解,过0.22 μm滤膜,采用高效液相色谱-串联质谱法(HPLC-MS/MS)测定其中林可霉素、克林霉素、洛美沙星、培氟沙星、恩诺沙星和环丙沙星等6种抗生素的含量,质谱分析采用多反应监测模式。结果表明,6种抗生素的质量浓度在0.001~1.0 mg·L^-1内与对应的峰面积呈线性关系,检出限(3S/N)为0.004~0.019 μg·kg^-1。方法用于分析单标准溶液和加标样品溶液,所得测定值的相对标准偏差(n=6)均小于4.0%。按标准加入法进行回收试验,回收率为83.8%~105%。方法用于实际样品分析,6种抗生素的检出量为15.7~221.6 μg·kg^-1。

The representative soil samples (about 1 kg) were randomly selected and divided into four parts, about 200 g of which was air dried, pulverized and sifted. 10.0 g of the above soil sample was taken into the extraction pool, and 15.0 g of diatomite was added. After mixing evenly, accelerated solvent extraction (ASE) was carried out, and the extract was purified by a gel purification system. 10 mL of the purified solution was taken and blown to nearly dryness at 50 ℃ by nitrogen. The residue was dissolved in 1 mL of methanol and the solution was passed through 0.22 μm filtration membrane. 6 antibiotics including lincomycin, clindamycin, lomefloxacin, pefloxacin, ennofloxacin and ciprofloxacin were determined by high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS). Multiple reaction monitoring mode was used for MS analysis. As shown by the results, linear relationships between the values of corresponding peak area and mass concentration of 6 antibiotics were found in the range of 0.001-1.0 mg·L^-1, with detection limits (3S/N) in the range of 0.004-0.019 μg·kg^-1. The single standard solution and the spiked sample solution were analyzed by this method, with RSDs (n=6) of the determined values less than 4.0%. Test for recovery was made by standard addition method, giving results in the range of 83.8%-105%. This method was applied to analysis of actual samples, and the detection amounts of 6 antibiotics were 15.7-221.6 μg·kg^-1.