反相离子对色谱-电感耦合等离子体质谱法测定明胶空心胶囊中铬的形态

Determination of chromium form Cr(Ⅲ) and Cr(Ⅵ) in the gelatin hollow capsule by RPIC / ICP-MS

目的建立明胶空心胶囊中的铬的形态检测方法。方法以0.25 mmol/L乙二胺四乙酸二钠-2 mmol/L四丁基氢氧化铵-5%甲醇为流动相,经Agilent Eclipse XDB-C18（3.0 mm×150 mm,5μm）色谱柱分离,微波提取反相离子对色谱分离电感耦合等离子体质谱完成明胶空心胶囊中的Cr（Ⅲ）和Cr（Ⅵ）测定。结果水微波提取和分析过程中Cr（Ⅲ）和Cr（Ⅵ）不相互转化,三价铬由于没有形成络阴离子,不会形成色谱峰,此时只能测定Cr（Ⅵ）,用乙二胺四乙酸二钠提取时,三价铬与之形成络阴离子,进而形成色谱峰,此时有部分六价铬转化为三价铬,根据峰面积计算出此时三价六价铬的含量总值,减去用水提取出的六价铬,即可得到三价铬真实含量。Cr（Ⅲ）、Cr（Ⅵ）检出限分别为0.6和0.51 mg/kg,线性范围：5~100μg/L。结论本方法能使用于明胶空心胶囊中铬形态的测定。

Objective To establish a method for the determination of chromium form Cr（ Ⅲ） and Cr（ Ⅵ）simultaneously in gelatin capsule. Methods Chromium in gelatin capsule was ultrasonic extracted and determined using reversed-phase ion-pair chromatography with inductively coupled plasma mass spectrometry（ RPIC / ICP-MS）. Results Cr（ Ⅲ） and Cr（ Ⅵ） were not interchangeable in the process of ultrasonic extraction and analysis,and only Cr（ Ⅵ） could be determined. When extracted by EDTA,both Cr（ Ⅲ） and Cr（ Ⅵ） could be measured. Because of the interconversion between Cr（ Ⅲ） and Cr（ Ⅵ）,the total chromium could be calculated accordding to peak area. The amount of Cr（ Ⅲ）could be determined by subtracting Cr（ Ⅵ） from the total chromium. The detection limit of Cr（ Ⅲ） and Cr（ Ⅵ） were0. 67 and 0. 51 mg / kg,and the linear range was 5-100 μg / L. Conclusion This method could be used to determine the chromium form in gelatin capsule.