柱前衍生毛细管电泳-电致化学发光法测定瓜瓤组织中的瓜氨酸含量

Determination of Citrulline Content in Melon Pulp by Pre-column Derivatization Capillary Electrophoresis Coupled with Electrochemiluminescence Detection

以甲醛和硼氢化钠为主要衍生反应试剂,对瓜氨酸分子中的α-氨基进行N-甲基化得到具有强电致化学发光信号的单一衍生产物。据此建立了一种用毛细管电泳-电致化学发光法(CE-ECL)高选择性测定瓜瓤组织中瓜氨酸含量的新方法。在优化的实验条件下,瓜氨酸的衍生物可在5 min内达到电泳分离,且瓜氨酸浓度在9.0～250μmol/L范围内时,其衍生物的电泳峰强度值与待测浓度间呈良好的线性关系(r^2=0.999 6),检出限(S/N=3)为3.2μmol/L。对同一标准样品平行进样6次,测得其电泳峰强度值和迁移时间值的相对标准偏差分别为2.6%和0.92%。此外,采用标准加入法对4种鲜瓜瓤组织中的瓜氨酸进行了定量测定,结果表明西瓜、甜瓜、籽瓜、哈密瓜的鲜瓜瓤组织中瓜氨酸的含量分别为2.75、0.95、1.26、1.19 mg/g,对实际样品的加标回收率为91.4%～106%。

A new method for the highly selective determination of citrulline in the melon pulp was established by capillary electrophoresis coupled with electrogenerated chemiluminescence detection (CE-ECL ),based on the N-methylation derivatization reaction of the α-amino groups in citrulline molecules,with formaldehyde and sodium borohydride as main derivatization reagents to obtain a single derivative product emitting a strong electrochemiluminescence signal.Under the optimized experimental conditions,the citrulline derivative could be separated within 5 min,and there existed a good linear relationship ( r ^2 =0.999 6 )between the electrophoretic peak intensity of the derivative and the original concentration of citrulline in range of 9.0-250 μmol/L with the detection limits of 3.2 μmol/L ( S/N =3 ).The relative standard deviations of peak height and migration time for the same standard sample ( n=6 )were 2.6 % and 0.92 %,respectively.Additionally,four kinds of actual melon samples were quantitatively determined by the standard addition method.Results showed that the citrulline contents in fresh melon pulp tissues of watermelon,melon,seeding melon and cantaloupe melon were 2.75,0.95,1.26 and 1.19 mg/g,respectively,while the recoveries for these real samples were between 91.4 % and 106 %.