Rapid determination of bisphosphonates by ion chromatography with indirect UV detection

Rapid methods for etidronate, clodronate, pamidronate, and alendronate assays are presented. The methods are based on ion chromatography with indirect UV detection, which avoids the need for chemical derivatization procedures. Each compound is analyzed on an individual basis. There is no need for having separation among these analytes because the aim of the proposed methods is to analyze each compound separately either in bulk material or pharmaceuticals. Phenosphere (150 x 2.0-mm, 5 μm) and Sphereclone (250 x 2.0-mm, 5 μm) anion exchange columns were employed with sodium citrate (20mM) as the mobile phase. The methods are simple, rapid (analysis time of 5 min for etidronate and clodronate and 7 min for alendronate and pamidronate), and demonstrate precision (relative standard deviation was lower than 2.0% in all concentrations), accuracy, and specificity. Calibration curves are linear with r2 > 0.99 over the concentration range of 50 to 400 μg/mL for etidronate and clodronate, and of 100 to 500 μg/mL for pamidronate and alendronate. Furthermore, they employed silica-based columns, which are cheaper than polymeric columns frequently used in previous reported methods.