Evaluation of multidimensional capillary electrophoretic methodologies for determination of amino bisphosphonate pharmaceuticals

Alendronate and pamidronate are amino bisphosphonate analogues of pyrophosphate used for the treatment of a variety of bone diseases. Analysis of these compounds is problematic due to their polar ionic nature, lack of a suitable chromophore and chelation properties and current analytical approaches involve extensive sample preparation and derivatization procedures. The potential of multidimensional capillary electrophoretic methodological approaches, which eliminate sample preparation have been evaluated for the analysis of these compounds both in aqueous and urinary matrices. Capillary isotachophoresis (cITP) was employed as a pre-separation and on-line sample concentration step prior to analytical determination using either cITP or capillary zone electrophoresis (CZE) with conductivity detection. Single cITP, cITP–cITP and cITP–CZE approaches were partially validated with respect to repeatability, recovery and linearity of response for both compounds. The increases in sensitivity achievable through increasing injection volume from 30 to 300 μL may render such strategies appropriate for determination of these agents at biologically relevant concentrations with minimal sample work-up.