A Convenient Approach to Simultaneous Analysis of a Pharmaceutical Drug and Its Counter-Ion by CE Using Dual-Opposite End Injection and Contactless Conductivity Detection

Abstract

Capillary electrophoresis (CE) coupled to a capacitively coupled contactless conductivity detector (C 4 D) was used for the determination in a single analysis of a pharmaceutical drug and its counter-ion. Dual-opposite end injection (DOI) was used to introduce hydrodynamically the analytes at each end of the capillary. No modification of the commercial apparatus is required. After applying the voltage, the cations and anions migrate from each end of the capillary in opposite directions toward the detector placed near the cathode outlet. The electrophoretic conditions were initially developed with three test drugs (chlorpheniramine maleate, metoprolol tartrate, clomiphene citrate) and then applied to two Vinca alkaloids (catharanthine sulfate, vinorelbine ditartrate). The 10 mM histidine-50 mM acetic acid buffer (pH 4.1)-methanol 90:10 (v/v) electrolyte was suitable for the analysis of these high or medium mobile anions by CE-C 4 D due to its low conductivity background and high buffer capacity. Finally, the CE procedure developed was successfully validated for catharanthine sulfate. The method developed herein is fast (\10 min) and accurate (repeatability on migration time \ 0.6% and peak areas \ 1.3%, n = 6).

Contactless conductivity detection for analytical techniques: Developments from 2010 to 2012

“…Other examples of CE‐C 4 D determination of non‐UV‐absorbing species in pharmaceutical preparations cover the analysis of antimycotic drugs , muscle relaxants , antiseptic/antimicrobial preparation , and manitol . Dual opposite end injection, which enables simultaneous CE analysis of cations and anions, was applied to the determination of basic drugs and their counter anions in various pharmaceutical formulations .…”

Recent advances in capillary electrophoretic migration techniques for pharmaceutical analysis (2013–2015)

“…A more efficient approach for simultaneous analysis of drug compound and its counter ion by CE is referred to as “dual‐opposite end injection” which involves the simultaneous injection of the sample at the same time from both anodic and cathodic ends of the capillary. Cations migrating to the cathode and anions migrating to the anode will pass a detector in the center of the capillary.…”

“…The application of dual‐opposite end injection for simultaneous determination of drug and its counter‐ion applying either UV or C 4 D detection was reported . Particularly the use of dual‐opposite end injection and contactless conductivity detection (DOE‐CE‐C 4 D) is currently an attractive CE approach to easily quantify a drug and its counter‐ion in the same run .…”

Dual‐opposite injection capillary electrophoresis: Principles and misconceptions

“…The distinction between the movement of the detector itself (e.g., C 4 D) versus the movement of the detection window in spectroscopic‐based detection methods with respect to instrument design may be confused or overlooked by some readers. However, when using the C 4 D detector, a window for detection is not necessary and therefore, the detector itself is moved along the capillary to avoid co‐detection between oppositely charged analytes. For manuscripts referencing DOI‐CE works published after 2002, it will be important for the reader to discern which type of detector was used in order to better understand the design of the experiment.…”