Assay of acebutolol in pharmaceuticals by analytical capillary isotachophoresis

Acebutolol [N-{3-acetyl-4-[(2-hydroxy-3-(isopropylamino)propoxy]phenyl} butanamide] is a cardioselective β-blocker with a potent antihypertensive and antiarrhythmic effect. The optimised operational system of electrolytes for the newly developed ITP separation of acebutolol consisted of 10 mM potassium acetate +10 mM acetic acid (pH 4.65) as the leading electrolyte and 10 mM β-alanine with pH ≈4 (adjusted with acetic acid) as the terminating electrolyte. The driving and detection currents were 75 and 20 μA, respectively and the analysis took ≈13 min. Under these conditions the effective mobility of acebutolol was determined as 20.7 × 10−9 m2 V−1 s−1. The calibration dependence was rectilinear in the range 0.14-1.4 mg ml−1 of acebutolol base (r = 0.9995); relative standard deviation (RSD) values were 1.1% and 1.2% (n = 6) when determining 0.42 and 0.98 mg ml−1 of acebutolol in a pure standard solution. The method, with the limit of detection (LOD) of 0.04 mg ml−1 and limit of quantification (LOQ) of 0.12 mg ml−1, was applied to the assay of acebutolol in Sectral tablets, Acecor tablets, Apo-acebutol tablets (nominal content 400 mg of acebutolol per tablet) and Acebirex tablets (nominal content 200 mg of acebutolol per tablet) with RSD = 0.7-1.7% (n = 6). No interference from any excipients present in the tablets was observed. The recoveries ranged from 98.8% to 102.4% as found by the standard addition technique.