高效液相色谱法测定巧克力中胭脂树橙的含量

Determination of annatto in chocolate by high performance liquid chromatography

目的建立高效液相色谱法测定巧克力中胭脂树橙含量的分析方法。方法采用氨水乙醇提取样品中的色素,石油醚除脂后,在酸性条件下采用二氯甲烷反提取目标物,选用C18色谱柱分离,以乙腈:2%乙酸(75:25,V:V)作为流动相进行等度洗脱,用紫外检测器在458 nm波长检测,外标法定量。结果降红木素的定量限为1.0 mg/kg,红木素的定量限为2.0 mg/kg,线性范围为1~50 mg/kg。降红木素和红木素回收率分别为87.8%~92.0%和88.7%~92.1%,相对标准偏差(relative standard deviation,RSD)分别为1.1%~5.0%和1.7%~5.2%。结论本方法简单、便捷,适用于巧克力中胭脂树橙含量的测定。

Objective To establish a method for determination of annatto in chocolate by high performance liquid chromatography.Methods The pigment in the sample was extracted with ammonia water ethanol,and defatted by petroleum ether.Then,the target compound was back-extracted with dichloromethane under acidic conditions,and separated on a C18 column and isocratic eluted with acetonitrile:2%acetic acid(75:25,V:V)as mobile phase.The targets were detected by a ultraviolet detector at the wavelength of 458 nm,and quantified by external standard method.Results The limits of quantification of norbixin and bixin were 1.0 mg/kg and 2.0 mg/kg,respectively.The linearities of norbixin and bixin ranged from 1 to 50 mg/kg.The spiked recoveries of norbixin and bixin ranged from87.8%-92.0%and 88.7%-92.1%with the standard deviations of 1.1%-5.0%and 1.7%-5.2%,respectively.Conclusion This method is simple and convenient,which is suitable for the detection of annatto in chocolate samples.