DETERMINATION OF PAMIDRONATE IN URINE BY ION-PAIR LIQUID-CHROMATOGRAPHY AFTER DERIVATIZATION WITH 1-NAPHTHYLISOTHIOCYANATE

A sensitive method for the determination of pamidronate disodium [(3-a mino-1-hydroxypropylidene)bisphosphonate, APD] in urine has been devel oped and validated, The procedure involves a triple co-precipitation w ith calcium phosphate, solid-phase extraction on a quaternary ammonium column, derivatization with 1-naphthylisothiocyanate and ion-pair liq uid-liquid extraction. From the two reaction products, naphthylthiocar bamyl-APD is converted into the other, naphthylcarbamyl-APD, by an oxi dative desulphuration with hydrogen peroxide prior to analysis by ion- pair HPLC and fluorescence detection at 285/390 nm. The method has a c oefficient of variation of 7% for the intra-assay precision of 99 ng m l(-1) APD and 118 for the inter-assay precision, The lower limit of qu antification is 3 ng ml(-1) APD in 2.5 ml of human urine. (C) 1997 Els evier Science B.V.