High pressure liquid chromatographic separation and quantitation of chlordiazepoxide.HCl and two of its related compounds.

A method is described for the separation and quantitative determination of chlordiazepoxide. HCl and 2 related compounds, 7-chloro-1-3-dihydro-5-phenyl-2H-1,4-benzodiazepin-2-one-4-oxide (CBO) and 2-amino-5-chlorobenzophenone (ACB), by high pressure liquid chromatography. The 3 compounds are separated on a reverse phase microparticulate column packing, using a mobile phase of acetonitrile and aqueous ammonium acetate. Bulk powders or capsule formulations are quantitated by direct comparison of their peak heights to those of appropriate reference standards. Data are presented showing the limit of detectability for the related compounds to be less than 80 ng CBO/ml and less than 40 ng ACB/ml. Based on peak heights, the relative standard deviation for the precision for chlordiazepoxide.HCl is 0.42%. Recoveries from laboratory-prepared samples for chlordiazepoxide.HCl were 99.4%; CBO, 102.4%; and ACB, 99.7%.