Evaluation and validation of an HPLC procedure for the determination of the positional isomeric impurity in 2-[4-(1-hydroxy-4-[4-(hydroxydiphenylmethyl)-1-piperidinyl]-butyl)-phenyl]-2-methylpropionic acid

A high-performance liquid chromatographic (HPLC) procedure was evaluated for the determination of a positional isomeric impurity in bulk 2-[4-(1-hydroxy-4-[4-(hydroxydiphenylmethyl)-1-piperidinyl]-butyl)-phenyl]-2-methylpropionic acid HCl drug substance. The use of a β-cyclodextrin bonded-phase column with a mobile phase of 20/80 (v/v) acetonitrile/water containing an ammonium acetate buffer at apparent pH 4.0 and a flow rate of 0.45 mL/min resulted in an excellent separation of the isomers. Ultraviolet detection was used at 220 nm. A recovery study of known spike levels (0.1 to 1.5% w/w) showed that the procedure was accurate. A two-day, two-column repeatability study showed consistent results with the test batch of the bulk compound. The level of impurity in the tested lot of the compound had a mean level of 0.32% (w/w) and a standard deviation of 0.038% (w/w, n = 5). The text was submitted by the author in English.