Methods for the quantitation of bromosulfophthalein and its glutathione conjugate in biological fluids

This paper describes a solvent-gradient HPLC method which was developed for the quantitation of bromosulfophthalein (BSP) in erythrocyte and albumin containing (blood) perfusate samples, and of BSP and its glutathione conjugate (BSP-GSH) in bile samples obtained from rat liver perfusion experiments. Phenolphthalein was used as an internal standard. The cysteinyl-, N-acetylcysteinyl-, and cysteinylglycinyl-BSP conjugates did not interfere with the HPLC assay and cysteine, N-acetylcysteine, [3H]GSH, and [3H]GSSG eluted within the first 6 min postinjection onto the HPLC system. A spectrophotometric method was also developed for the rapid quantitation of BSP in blood perfusate; tracer [14C]urea was utilized as the internal standard. Although the spectrophotometric method was less sensitive than the HPLC method, good correlation was found to exist between the methods.