title: Use of the caffeine reagent in direct spectrophotometry of bilirubin.
abstract: The molar absorptivity of unconjugated bilirubin in caffeine reagent is independent of the protein matrix. This finding, together with the simplicity of a dilution step for direct spectrophotometry, will improve the calibration methods of bilirubin and make them more nearly accurate. This is encouraging for the development of a new method for bilirubin determination in neonates; moreover, the caffeine reagent has a clearing influence on the turbidity of human sera. These findings should also be important for standardization, especially because the method of Jendrassik and Gróf is also protein-independent. Therefore, the introduction of one reliable, inexpensive, "universal" standard of bilirubin in bovine serum albumin will be of importance for both methods.
mesh_terms: D001663:Bilirubin / Q000097:blood* / Q000592:standards; D001881:Borates; D002110:Caffeine; D006801:Humans; D007202:Indicators and Reagents; D007231:Infant, Newborn; D008433:Mathematics; D012709:Serum Albumin; D012996:Solutions; D013053:Spectrophotometry / Q000379:methods
chemical_list: D001881:Borates; D007202:Indicators and Reagents; D012709:Serum Albumin; D012996:Solutions; D002110:Caffeine; D001663:Bilirubin