取家畜尿样10.0 mL置于离心管中，加入自制的磁性石墨烯50 mg，用10 mmol·L^-1氢氧化钠溶液调节混合物的酸度至pH 8.0，超声提取20 min。用碳铁分离液固两相，弃去液相，先后3次超声提取固相，每次用乙腈2 mL，提取5 min。将3次所得液相合并，置于40℃水浴中吹氮至近干，盐类用乙腈和0.1%（体积分数，下同）甲酸溶液（1+9）的混合液1.0 mL溶解，所得溶液经0.22 μm滤膜过滤，在所选定的仪器工作条件下，对所要测定的10种苯并二氮杂卓类化合物（BZDs）进行色谱分离和质谱测定。采用Acquity UPLC HSS T3色谱柱为固定相，以（A）0.1%甲酸溶液和（B）含0.1%甲酸的乙腈混合液为流动相，按梯度洗脱程序进行分离；质谱测定选用电喷雾离子源、正离子扫描和多反应监测模式。结果表明：10种BZDs在1.0~100.0 μg·L^-1范围内与其峰面积值呈线性关系，其测定下限（10S/N）在0.09~0.40 μg·L^-1之间。以空白猪尿液为基质，按标准加入法进行回收试验，测得回收率在74.6%~95.2%之间，测定值的相对标准偏差（n=6）在2.5%~9.4%之间。

An aliquot (10.0 mL) of the urine sample of domestic animal was taken and mixed with 50 mg of the self-prepared Fe₃O₄-G; the acidity of the mixture was adjusted to pH 8.0 by adding 10 mmol·L^-1 NaOH solution and the mixture was then extracted ultrasonically for 20 min. The solid and liquid phases were separated with magnetic iron, the liquid phase was discarded, and the solid phase was then extracted thrice with CH₃CN (2 mL were used for each extraction of 5 min). The 3 extracts were combined and evaporated to near-dryness by N₂-blowing in a water bath at 40℃. 1.0 mL of a mixture of acetonitrile and 0.1% (φ) formic acid solution (1+9) was added to dissolve the residue. The solution was filtered through 0.22 μm filtering membrane, and the filtrate was used for HPLC separation of the 10 benzodiazepines (BZDs) and their determination by MS/MS, under precribed instrumental conditions. Acquity UPLC HSS T3 column was used as stationary phase, and mixtures of (A) 0.1% (φ) formic acid solution and (B) acetonitrile containing 0.1% (φ) formic acid solution mixed were used as mobile phase in the separation by programmed gradient elution. The modes of ESI, positive-ion scanning and MRM were adopted in MS/MS analysis. As shown by the results, linear relationships between values of peak areas of the 10 BZDs and their mass concentrations were obtained in the same range of 1.0-100.0 μg·L^-1, with values of lower limits of determination (10S/N) in the range of 0.09-0.40 μg·L^-1. Using blank pig's urine sample as matrix, recovery was tested by standard addition method, giving results of recovery in the range of 74.6%-95.2%, values of RSDs (n=6) were found ranged from 2.5% to 9.4%.