SEPARATION OF PHARMACEUTICAL BASES FROM NEUTRAL AND ACIDIC COMPONENTSBY CAPILLARY ELECTROCHROMATOGRAPHY

Capillary electrochromatography (CEC) has proved to be applicable to t he separation of neutral and acidic (chromatographed in their ion-supp ressed mode) compounds but a major factor holding back its further dev elopment has been its perceived inability to analyse basic compounds. In this paper we demonstrate that the addition of a competing base, su ch as triethylamine (TEA) or triethanolamine (TEOA), to a low pH buffe r can achieve excellent CEC analysis of a range of strong pharmaceutic al bases. Acceptable peak symmetry and efficiencies of up to 510 000 p lates m(-1) were obtained for bases such as procainamide, nortriptylin e and diphenhydramine on CEC Hypersil C-18, C-8 and phenyl reversed-ph ase packing materials. The effect of TEA or TEOA concentration and mob ile phase pH on the separation behaviour of the bases is discussed. In addition, the paper reports the first example of the simultaneous CEC analysis of acids, bases and neutral compounds by using a mobile phas e containing TEOA phosphate at pH 2.5.