固相萃取-高效液相色谱法测定焦糖色素中副产物2-甲基咪唑、4-甲基咪唑和2-乙酰基-4-(1,2,3,4-四羟基丁基)咪唑

Simultaneous Determination of 2-Methylimidazole,4-Methylimidazole and 2-Acetyl-4-( 1,2,3,4-tetrahydroxybutyl) imidazole in Caramel Colours by Solid Phase Extraction-High Performance Liquid Chromatography

建立了固相萃取法结合高效液相色谱同时检测焦糖色素中2-甲基咪唑（2-Methylimidazole,2-MEI）、4-甲基咪唑（4-Methylimidazole,4-MEI）和2-乙酰基-4-（1,2,3,4-四羟基丁基）咪唑（2-Acetyl-4-（1,2,3,4-tetrahydroxybutyl）imidazole,THI）的方法。样品经加水涡旋提取后,经混合型强阳离子交换固相萃取小柱富集净化,以乙腈-0.05%氨水（10∶90,V/V）为流动相,流速为0.6 m L/min,用反向色谱柱Polaris C18-A（250 mm×4.6 mm,5μm）柱分离,分别在二极管阵列检测器215 nm波长条件下检测焦糖色素中的2-甲基咪唑、4-甲基咪唑和287 nm波长条件下检测2-乙酰基-4-（1,2,3,4-四羟基丁基）咪唑的含量。2-甲基咪唑、4-甲基咪唑和2-乙酰基-4-（1,2,3,4-四羟基丁基）咪唑在0.2~20 mg/L之间线性关系良好（r〉0.9996）,在10,25和100 mg/kg添加浓度的回收率范围为75.3%~93.4%,相对标准偏差均小于10%,检出限分别为为2.6,3.0和1.5 mg/kg,定量限分别为8.5,10.0和5.0 mg/kg。

An analytical method was developed to extract and determine 2-methylimidazole （2-MEI）, 4-methylimidazole （4-MEI） and 2-acetyl-4- （ 1,2,3,4-tetrahydroxybutyl ） imidazole （ THI ） in caramel colors using solid phase extraction and high performance liquid chromatographic （SPE-HPLC）. Caramel colours were dissolved in water and enriched and purified by strong cation exchange solid phase extraction. Then the purified solution was separated by Polaris Cls-A （250 minx4.6 mm, 5 μm） column and 2-MEI and 4-MEI were measured at UV wavelength of 215 nm and THI at UV wavelength of 287 nm with a mobile phase consisting of acetonitrile （A） and 0.05 % ammonia in water （ B ） in proportion of A ： B = 10： 90 （V!V）. The flow rate was 0.6 mL/min. The method had good linearity within the concentration range of 0.2-20 mg/L with correlation coefficients of greater than 0. 9996. The recoveries of 2-MEI, 4-MEI and THI were between 75.3%-93.4% and relative standard deviations （RSD） were less than 10% at three spiked level of 10 mg/kg, 25 mg/kg and 100 mg/kg. The limits of detection （LOD） were 2.6, 3.0 and 1.5 mg/kg and the limits of quantitation （LOQ） were 8.5, 10.0 and 5.0 mg/kg, respectively.