取水产养殖用非规范药品样品1.00 g,加入1.0 mg·L^-1扑草净-d₆(内标)溶液10 μL和水20 mL,其中固态样品经均质、超声处理后离心5 min,液态样品经涡旋振荡混匀后离心5 min,均取上清液用水定容至100 mL;养殖水样经0.45 μm滤膜过滤,取滤液200 mL,加入1.0 mg·L^-1扑草净-d₆溶液10 μL,振荡混匀。将上述样品溶液过NPO HLB固相萃取柱(预先用5 mL甲醇、5 mL水活化),用5 mL水淋洗,用6 mL甲醇洗脱,将洗脱液于40 ℃氮气吹至近干,加入体积比3∶7的甲醇-含0.1%(体积分数,下同)甲酸的2 mmol·L^-1乙酸铵溶液混合液1.0 mL复溶,经涡旋、超声振荡、离心、过滤后,采用超高效液相色谱-串联质谱法同时测定其中扑草净、阿维菌素和伊维菌素的残留量。以Waters ACQUITY UPLC C₁₈柱为固定相,以不同体积比的甲醇-含0.1%甲酸的2 mmol·L^-1乙酸铵溶液混合液为流动相进行梯度洗脱,质谱分析采用电喷雾离子(ESI)源,正离子(ESI⁺)扫描及多反应监测模式,内标法定量。结果表明:扑草净标准曲线的线性范围为0.2~15.0 μg·L^-1,阿维菌素、伊维菌素标准曲线的线性范围为2.0~150.0 μg·L^-1,非规范药品样品中检出限(3S/N)分别为0.2,2.0,2.0 μg·kg^-1,水样中检出限(3S/N)分别为1.0,10,10 μg·L^-1。按照标准加入法进行回收试验,回收率为84.8%~105%,测定值的相对标准偏差(n=6)小于9.0%。方法用于分析80个实际样品,结果显示,1个非规范药品样品中检出阿维菌素,其残留量为718 mg·kg^-1,1个水样中检出扑草净,其残留量为3.2 ng·L^-1。

The non-standard drug sample for aquaculture (1.00 g) was taken, and 10 μL of 1.0 mg·L^-1 prometryne-d₆ (internal standard) solution and 20 mL of water were added. The solid sample was centrifuged for 5 min after homogenization and ultrasonication, while the liquid sample was centrifuged for 5 min after stirring well by vortex oscillation, both in which the supernatant was taken and made its volume up to 100 mL with water. The aquaculture water sample was filtered through a 0.45 μm filter membrane, 200 mL of the filtrate was taken, and 10 μL of 1.0 mg·L^-1 of prometryne-d₆ solution was added, shaking and mixing well. The above sample solution was passed through NPO HLB solid phase extraction column (activated with 5 mL of methanol and 5 mL of water), washed with 5 mL of water, and eluted with 6 mL of methanol. The eluent was blown to near dryness at 40 ℃ by nitrogen. The residue was redissolved in 1.0 mL of a mixture of methanol and 2 mmol·L^-1 ammonium acetate solution containing 0.1% (volume fraction, the same below) formic acid at a volume ratio of 3∶7. After vortex, ultrasonic oscillation, centrifugation and filtration, the residues of prometryne, avermectin and ivermectin were determined by ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS), using Waters ACQUITY UPLC C₁₈ column as stationary phase and mixtures of methanol and 2 mmol·L^-1 ammonium acetate solution containing 0.1% formic acid at different volume ratios as mobile phase for gradient elution. Electrospray ion (ESI) source was used for mass spectrometry, with multiple reaction monitoring mode in positive scanning mode. Internal standard method was used for quantitative analysis. As shown by the results, the linear ranges of the standard curve were 0.2-15.0 μg·L^-1for prometryne, and 2.0-150.0 μg·L^-1 for avermectin and ivermectin, with detection limits (3S/N) of 0.2, 2.0, 2.0 μg·kg^-1 respectively in the non-standard drug samples, and 1.0, 10, 10 μg·L^-1respectively in water samples. Test for recovery was made by standard addition method, giving results in the range of 84.8%-105%, with RSDs (n=6) of the determined values less than 9.0%. This method was applied to the analysis of 80 actual samples, and it was shown that avermectin was detected with a residue of 718 mg·kg^-1 in a non-standard drug sample, and prometryne was detected with a residue of 3.2 ng·L^-1 in a water sample.