高效液相色谱法测定柑橘中喹啉铜的残留量

Determination of Residues of Oxine-Copper in Citrus by HPLC

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0.22μm水相滤膜过滤,滤液进入高效液相色谱仪,在SunFire■ C_(18)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 0.22μm aqueous phase filtration membrane,and analyzed by HPLC.The target compound was separated on SunFire■ C_(18) 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.