Rapid Spectrofluorometric Assay for Total Bile Salts in Bile

An assay is presented for total bile salts in bile. The procedure involves one precipitation and extraction step and then treatment with concentrated sulfuric acid to produce fluorescent products, which are then measured at an excitation wavelength of 470 nm and emission wavelength of 505 nm. With sodium taurocholate as the standard (fluorescence intensity of 1.00), the average fluorescence intensity of equimolar concentrations of the taurine and glycine conjugates of cholic, deoxycholic, and chenodeoxycholic acid is 1.01 (standard dev., 0.05). The average recovery of the six bile salts from pooled rat bile is 95.7% (standard dev., 8.5). The assay compares well with the established gas—liquid chromatographic and enzymatic methods, but it is simpler, faster, less costly, and just as reliable as the alternative methods.