Determination of bisphosphonates by ion-pair HPLC

The optimization of the two bisphosphonates (disodium pamidronate and zoledronic acid) separation by ion-suppression and ion-pair high-performance liquid chromatography is described. The influence of the eluent pH, composition of the mobile phase and the concentration of complexing ion-pairing agents was investigated. This developed method provides high separation and specificity to bisphosphonate analysis. In quantitative analysis in the optimized conditions (10mM n-amylamine or n-butylamine; 14% acetonitrile in 0.1 M sodium phosphate buffer, pH=7.0), the method showed good linearity (r=0.9999-0.9998) and sufficient sensitivity (10^-7-10^-8g/ml). It can be easily and conveniently adopted for the routine quality control analysis.