Short-end injection technique in capillary electrophoresis for dissolution testing of tablets

Abstract

A capillary electrophoresis (CE) method using short-end injection technique has been developed for dissolution testing of tablets of calcium acamprosate. After dilution of dissolution bath sample solution (in 0.1 M citric acid) in water, the sample (11.5 nl) was injected on the detector side in a fused silica capillary 31.2 cm long (21 cm to the detector)×50 μm internal diameter. Acamprosate was separated from sorbate (internal standard) in a 50 mM borate buffer solution applying a 500 V cm −1 electric field. The compounds were detected at 200 nm. Relative corrected peak areas (acamprosate/sorbate) were used for quantitation. The method was shown to be specific (versus tablet excipients), linear ( r 2>0.999), accurate (average recovery of 100.3% obtained by three analysts on 3 days at five levels) and repeatable (RSD<1%). The limits of detection and quantification corresponded, respectively, to 0.8 and 2.5% of drug released. Good agreement was found between the results obtained by the CE method and a liquid chromatography (LC) method with ion-pairing (maximum difference of 1.7% relative to the LC results), for sample solutions withdrawn from the dissolution bath. CE presents the advantage of being more rapidly set-up and executed than LC (4 versus 12 min).