超高效液相色谱-荧光检测法准确定量调味油中罗丹明B的两种前处理方法比较

Two pretreatment methods for the accurate determination of rhodamine B in chili oil by ultra-high performance liquid chromatography with fluorescence detection

目的研究有效提取和净化调味油中罗丹明B的两种前处理方法,为超高效液相色谱-荧光检测(UPLC-FLR)法的准确定量提供有价值的参考。方法第一种方法用酸化乙腈提取,混合型阳离子交换固相萃取(SPE)柱净化;第二种方法用含20%丙酮的正己烷提取,中性氧化铝SPE柱净化。两种方法的净化液吹至近干,用50%甲醇-水复溶,滤膜过滤后用UPLC-FLR测定。结果两种方法中罗丹明B在5.0、50.0、200.0μg/kg三个水平下的加标回收率分别在82.8%~101.9%、80.9%~93.6%之间,相应相对标准偏差(RSD)分别在1.5%~2.9%(n=6)、1.0%~2.1%(n=6)之间。结论两种方法均可满足调味油中罗丹明B的测定,第一种方法在5.0、50.0μg/kg加标水平的回收率均优于第二种方法,且无需大容量SPE柱;高浓度(200.0μg/kg)加标水平的回收率差异无统计学意义(P>0.05)。

Objective Two sample pretreatment method for the effective extraction and purification of rhodamine B in chili oil were investigated in detail. Valuable information for the accurate assay of rhodamine B by ultra-high performance liquid chromatography with fluorescence detection（ UPLC-FLR） was provided. Methods The chili oil was extracted with acidified acetonitrile and then purified by a mixed type cation exchange solid phase extraction（ SPE） column in the first method. In the second method,n-hexane containing 20% acetone was used to extract rhodamine B. The extraction was then purified by a neutral alumina SPE column. Both of the purified sample solution was blown to nearly dryness,redissolved in 50% methanol-water,filtrated and then analyzed by UPLC-FLR. Results The recoveries at three spiked levels（ 5. 0,50. 0,200. 0 μg/kg,respectively） were in the ranges of 82. 8%-101. 9% and 80. 8%-93. 6%,with relative standard deviations ranging from 1. 5%-2. 9%（ n = 6） and 1. 0%-2. 1%（ n = 6）,respectively. Conclusion Both of the two pretreatment method could meet the requirements of accurate determination of rhodamine B in chili oil. However,the recoveries at spiked levels（ 5. 0 and 50. 0 μg/kg） of the first method were higher than those of the second method.Furthermore,no large capacity SPE column was needed. There was no significant difference between recoveries of the two method at high spiked level（ 200. 0 μg/kg）.