柑橘样品经随机采摘、手工分离、匀浆和缩分后,分取柑橘全果、橘肉、橘皮样品各5.00 g,加入体积比为1∶9的0.1%(体积分数)三氟乙酸溶液和乙腈的混合溶液(流动相)10 mL及氯化钠3 g,涡旋5 min混匀,超声提取20 min,离心5 min,重复提取一次。合并上清液,分取5 mL,用5 mg石墨化碳黑(GCB)净化,离心5 min。分取上清液4 mL,旋转蒸发至近干,用1 mL流动相复溶,用0.22 μm水相滤膜过滤,滤液进入高效液相色谱仪,在SunFire^® C₁₈色谱柱上用流动相进行等度洗脱分离,得到的目标物在检测波长254 nm处检测。结果表明:喹啉铜的质量浓度在0.1~5.0 mg·L^-1内与其对应的峰面积呈线性关系,检出限为0.1 mg·kg^-1。以阴性柑橘全果、橘肉、橘皮样品为基质进行3个浓度水平的加标回收试验,回收率为83.6%~95.6%,测定值的相对标准偏差(n=5)为2.3%~6.7%。方法用于实际样品的分析,未检出喹啉铜的残留,用于按照推荐剂量喷施2 h后柑橘样品的分析,在全果和橘皮中检出喹啉铜的残留。

Citrus samples were randomly picked, manually separated, homogenized and reduced, and an aliquot (5.00 g) of citrus whole fruit, flesh and peel was taken respectively. The mixed solution (mobile phase, 10 mL) of 0.1% (volume fraction) trifluoroacetic acid solution and acetonitrile at volume ratio of 1:9 and 3.0 g of sodium chloride were added into the samples, the mixture was treated by vortex mixing for 5 min, ultrasonic extraction for 20 min and centrifugation for 5 min, and the extraction was repeated once again. The supernatants obtained were combined, an aliquot (5 mL) was purified by 5 mg of GCB. After centrifugation for 5 min, 4 mL of the supernatant was evaporated by rotation to nearly dry. The residue was redissolved by 1 mL of mobile phase, filtered by a 0.22 μm aqueous phase filtration membrane, and analyzed by HPLC. The target compound was separated on SunFire^® C₁₈ column with mobile phase by isocratic elution, and detected at wavelength of 254 nm. It was shown that linear relationship between values of mass concentration of oxine-copper and its peak area was kept in the range of 0.1-5.0 mg·L^-1, with detection limit of 0.1 mg·kg^-1. Test for the spiked recovery was made at three concentration levels with negative citrus whole fruit, flesh and peel as matrices, giving recoveries in the range of 83.6%-95.6%, and RSDs (n=5) of the determined values ranged from 2.3% to 6.7%. The proposed method was applied to the analysis of actual samples, oxine-copper was not detected, and the residue of oxine-copper could be detected in citrus samples of whole fruit and peel after spraying at the recommended dose for 2 h.