The Quantitation of a Residual Quaternary Amine in Bulk Drug and Process Streams Using Capillary Electrophoresis

A capillary electrophoretic method for the determination of a residual alkyl quaternary amine, tetra-n-butylammonium ion (TBA+), in bulk drug and process streams was developed. Since the analyte does not have a chromophore, detection was performed utilizing indirect photometric detection. The influence of the quinine, tetrahydrofuran and sodium acetate concentrations and pH app in the background electrolyte solution upon the efficiency of the separation and effective electrophoretic mobility of both TBA+ and electro-osmotic flow were studied. The ranges in which the various parameters were examined had considerable effects upon both the efficiency and the effective electrophoretic mobility of the electro-osmotic flow; however, the effective electrophoretic mobility of TBA+ was not significantly affected. The optimized method was validated in terms of detector linearity, sensitivity, precision and accuracy.