The determination of pamidronate in pharmaceutical preparations by ion-pair liquid chromatography after derivatization with phenylisothiocyanate

An analytical method was developed for the determination of pamidronate [(3-amino-1-hydroxypropylidene)bisphosphonate] by ion-pair liquid chromatography. The analyte was derivatized with phenylisothiocyanate into an UV-absorbing, derivative. The reaction product was cleaned-up by a double ion-pair extraction and treated with hydrogen peroxide prior to injection. Both, the detection limit and the lower limit of quantification of pamidronate in water were 0.1 μg ml ^-1 disodium pamidronate. The intra-day precision was 3% for a 5-μg ml ^-1 pamidronate standard solution and the inter-day precision 6% for a 3-μg ml ^-1 solution. The method was applied in the quality control of pamidronate injection concentrates and tablets.