Marák Jozef, Mikus Peter, Maráková Katarína, Kaniansky Dusan, Valásková Iva, Havránek Emil
Department of Analytical Chemistry, Faculty of Natural Sciences, Comenius University, Mlynská Dolina CH-2, SK-842 15 Bratislava, Slovak Republic.
J Pharm Biomed Anal. 2008 Apr 14;46(5):870-6. doi: 10.1016/j.jpba.2007.05.019. Epub 2007 May 25.
The present work illustrates potentialities of on-line combined isotachophoresis-capillary zone electrophoresis (ITP-CZE) separation techniques coupled with on-capillary diode array detector (DAD) for enantiomeric purity testing of drugs in pharmaceuticals. The general advantages of the proposed method are its (i) high selectivity, (ii) low concentration limit of detection (LOD) obtainable, (iii) enhanced sample loadability, and (iv) enhanced reliability. For separation of brompheniramine (BP) enantiomers, serving as model analytes, carboxyethyl-beta-cyclodextrin (CE-beta-CD) was appropriate chiral selector providing complete enantioresolution. Given by a high sample load capacity (30 microl sample injection volume) and preconcentration of the analytes in ITP stage, concentration LOD of levobrompheniramine (LBP), serving as model impurity, was 2.5 ng/ml (8 x 10(-9)mol/l). Such separation and detection conditions enabled to easily determine LBP in samples containing a 10(3) excess of dexbrompheniramine (DBP). DAD detection in comparison with single wavelength detection can enhance value of analytical information when analytes and interferents have different spectra (distinguishing impurities in analyte zone, confirmation of migration positions of migrants). In this context purity of BP zones was confirmed with higher reliability in pharmaceutical sample. Moreover, distinguishing the trace analyte signal superposed on the baseline noise was provided with sufficient reliability (for this purpose the background correction and smoothing procedure had to be applied to the raw DAD spectra). Successful validation and application of the proposed ITP-CZE-DAD method suggest its routine use for the enantiomeric purity testing of pharmaceuticals.
本研究展示了在线等速电泳 - 毛细管区带电泳（ITP - CZE）分离技术与毛细管二极管阵列检测器（DAD）联用在药物对映体纯度检测方面的潜力。该方法的总体优势在于：（i）高选择性；（ii）可实现的低检测浓度限（LOD）；（iii）增强的样品负载能力；（iv）更高的可靠性。以溴苯那敏（BP）对映体作为模型分析物进行分离时，羧乙基 - β - 环糊精（CE - β - CD）是合适的手性选择剂，可实现完全的对映体拆分。鉴于高样品负载量（进样体积30微升）以及在ITP阶段对分析物的预富集，作为模型杂质的左溴苯那敏（LBP）的浓度LOD为2.5纳克/毫升（8×10⁻⁹摩尔/升）。这样的分离和检测条件能够轻松测定含有10³倍过量右溴苯那敏（DBP）的样品中的LBP。与单波长检测相比，当分析物和干扰物具有不同光谱时（区分分析物区域中的杂质、确认迁移物的迁移位置），DAD检测可增强分析信息的价值。在此背景下，药物样品中BP区域的纯度得到了更高可靠性的确认。此外，能够以足够的可靠性区分叠加在基线噪声上的痕量分析物信号（为此必须对原始DAD光谱应用背景校正和平滑程序）。所提出的ITP - CZE - DAD方法的成功验证和应用表明其可常规用于药物的对映体纯度检测。
