Determination of etidronate disodium and its related substances in its tablets by ion chromatography

Objective:To establish an ion chromatography method with suppressed conductivity detection for the determination of Etidronate Disodium and its related substances in Etidronate Disodium and its tablets.Methods:The separation was performed on an Ionpac AS11-HC anion exchange column eluted with 30 mmol L-1 potassium hydroxide solution at an isocratic elution program.Etidronate Disodium and its related substances such as phosphate,phosphite were determined by suppressed conductivity detection.Results:A good linear relationship was observed in the concentration range of Etidronate Disodium of 0.0021-0.1243 g·L-1(r=0.9997).The limits of detection were 0.66 ng,0.36 ng,0.15 ng for Etidronate Disodium,phosphate and phosphite.The average recovery of the tablets was 98.0%(RSD=0.5%).The related substances gained a completely chromatography separation with the principal peak.Conclusion:The method is accurate,sensitive and simple,which provides a new reliable analytical method for the quality control of etidronate disodium and its tablets.