Analysis of small amines in pharmaceuticals by capillary ion electrophoresis with conductivity detection

Capillary ion electrophoresis (CIE) with direct conductivity detection is a simple, fast, and versatile method for analysis of ions. In this study CIE with conductivity detection was used to analyze for hydroxylamine which is often used in the synthesis of pharmaceutical intermediates and drug substances. The conductivity response of hydroxylamine was investigated by using different buffer types and buffer concentrations. Other small amines were also studied with this method and were correlated with the molecular weight of the amines. The response of hydroxylamine increased significantly with MES–glycylglycine buffer as compared to MES–histidine buffer (LOD from 10 to 1 ppm). The detection of trace level of hydroxylamine in a drug substance proved to be possible with this method. The developed method was also tested for the linearity range, reproducibility, and selectivity with several small amines. The method developed in this study was demonstrated as a sensitive and reliable method for detection and quantification of small amines in pharmaceutical substances.