Determination of bisphosphonates by ion chromatography–inductively coupled plasma mass spectrometry

An ion chromatography–inductively coupled plasma mass spectrometry (IC–ICP-MS) was introduced in the analysis of bisphosphonates. Two compounds (alendronic acid and etidronic acid) were separated on a Dionex AS-7 anion-exchange column with dilute nitric acid employed as the mobile phase. The analytes were detected at m/z 31, as they contain phosphorus. The detection limits achieved were 0.20 mg l−1 for alendronic acid and 0.05 mg l−1 for etidronic acid. Since the determination of phosphorus by ICP-MS is difficult due to polyatomic interferences at m/z 31 (15N16O+, 14N16O1H+, and 12C1H316O+), a detailed study of the influence of plasma parameters on phosphorus and background signal was performed.