取匀浆后的蔬菜样品5.000 g，加入甲酸-乙腈（1+99）混合液10.0 mL，振荡提取20 min，加入氯化钠2.0 g，继续振荡20 min，离心5 min。分取上清液1.5 mL，加入由N-丙基乙二胺100 mg、十八烷基硅烷100 mg和自制的磁化碳纳米管10 mg混合组成的净化剂进行QuEChERS提取净化，混合物经0.22 μm滤膜过滤。滤液供高效液相色谱-串联质谱法分析。色谱分离中，选用Waters Cortects C₁₈色谱柱为固定相，以不同比例组成的乙腈（A）和5 mmol·L^-1乙酸铵溶液（B）的混合液为流动相进行梯度洗脱。洗脱液中29种除草剂的残留量按质谱条件进行测定。结果表明：29种除草剂的质量浓度均在5.0~40 μg·L^-1范围内与对应的峰面积呈线性关系，检出限（3S/N）在0.5~1.5 μg·kg^-1之间。以空白蔬菜样品为基体，用标准加入法进行回收试验，测得29种化合物的回收率在83.9%~99.7%之间，测定值的相对标准偏差（n=6）在1.3%~5.6%之间。

A portion of 5.000 g of the homogenized and pulpified vegetable sample was taken and extracted by shaking for 20 min with 10.0 mL of a mixture of formic acid and acetonitrile (1+99), 2.0 g of NaCl were added to the mixture and the shaking was continued for another 20 min. After centrifuging for 5 min, an aliquot of 1.5 mL of the supernatant was taken and purified by QuEChERS with a powder mixture containing 100 mg each of N-propyl ethylenediamine and octadecyl silane and 10 mg of self-prepared magnetized carbon nanotubes. The mixture was then filtered through 0.22 μm filtering membrane, and the filtrate was used for HPLC-MS/MS analysis. In the HPLC separation, Waters Cortects C₁₈ column was selected as stationary phase and mixtures of CH₃CN (A) and 5 mmol·L^-1 CH₃COONH₄ solution (B) with various ratios were used as mobile phase in the gradient elution. Residual amounts of the 29 herbicides in the eluates were determined by MS/MS under the instrumental conditions. As shown by the results, linear relationships between values of peak area and mass concentration of the 29 herbicides in the range of 5.0-40 μg·L^-1 were obtained, and the detection limits (3S/N) in the range of 0.5-1.5 μg·kg^-1. Test for recovery by standard addition method was made using a blank vegetable sample as matrix, giving results in the range of 83.9%-99.7%, and RSDs (n=6) ranged from 1.3% to 5.6%.