Chiral ligand-exchange capillary electrophoresis is flexible but can not be applied to the analysis of unknown samples or chiral compounds without a chiral ligand. We tried to solve this problem by exploring some non-analyte chiral ligands aiming at the assaying the L-dopa tablets. With aromatic D, L-amino acids ( dopa analogues) as mimetic analytes, chiral selecting systems of Cu2+-tartarate and Ni2+-tartarate were obtained among the metal complexes of Cu2+, Ni2+, Zn and Co2+ formed from tartaric, lactic and malic acids. Cu2+ -tartarate worked better at an acidic condition while Ni2+ -tartarate better at a weakly basic condition. The latter system suited for quantitative analysis of L- and D-dopa in oral tablets. Its linear range was in between 0. 025-2. 5 mmol/L D- or L-dopa, with linear coefficients all above 0. 9999 and recovery at around 96. 3%. The detection limit reached about 0. 5% (mass fraction) D-dopa. Several batches of L-dopa oral tablets were then assayed, given the content of (97. 33+0. 70)% (mass fraction) of the specified data. The ratio of ligand to central ion was found to be the most crucial factor, besides, pH and complex concentration were also highly important. Other conditions such as additives and the type of buffer reagents impacted also obviously on the chiral resolution and better optimized.%以L-多巴为测定目标,以天然芳香氨基酸为替代样品,建立了以非样品α-羟基酸为手性配体,以铜和镍等二价金属为中心离子的手性配体交换毛细管电泳新方法.当弱配位的α-羟基酸与中心离子的摩尔比大于6∶1时,所建立的方法即可实现对D,L-氨基酸和D,L-多巴的基线分离,可用于口服多巴药片含量的测定,检测出质量分数为0.5％的异构体杂质,其定量的线性范围是0.025～2.5 mmol/L,回收率为96.3％.据此方法测得某商品药片的实际含量(质量分数)为标称值的(97.33±0.70)％.
展开▼
