Chromatographic analysis of bisphosphonates

Chromatographic analysis of bisphosphonates in the past has been based prim arily on reversed-phase liquid chromatography (RPLC) and ion-exchange chrom atography. Gas chromatography (CC) and recently even capillary electrophore sis have also been employed. For bioanalysis, pre-treatment of the sample i s a major part of the analysis; protein precipitation, calcium precipitatio n, solid-phase extraction (SPE) and derivatization have demonstrated to pla y an important role in bisphosphonate assays. For some of these treatments, for example SPE and derivatization, automation may be possible. Derivatiza tion is a prerequisite for GC analysis of bisphosphonates; a volatile deriv ative has to be formed. For liquid chromatography, two types of derivatizat ion are known for bisphosphonates. Fiat, the bisphosphonate side chain can be modified by a chemical reaction to yield a derivative with advantageous chromatographic and spectroscopic properties. Secondly, by complexation of both phosphonate groups or of phosphate after decomposition of the analyte, a coloured complex can be formed. The most sensitive bioanalytical methods are based on RPLC and fluorescence detection, if necessary after derivatiz ation. if low detection limits are not required, for example for analysis o f pharmaceutical preparations, non-specific detection methods can be applie d.