Physiochemical studies of indocyanine green (ICG): absorbance/concentration relationship, pH tolerance and assay precision in various solvents.
Indocyanine green (ICG) obeyed the Beer-Lambert law within the concentration range 1.25 micrograms/ml-10.0 micrograms/ml in distilled water, methanol, dimethylformamide (DMF), 1.2-propanediol and aqueous buffers (pH 9.0), but only up to 7.5 micrograms/ml in human bile and 0.5% human albumin, and only to 5.0 micrograms/ml in human duodenal fluid. ICG was rapidly (less than 1 h) decomposed to a colorless derivative at pH less than 5 and greater than 11, but remained relatively stable for 48 h at pH 8-10. ICG is an indicator and a weak acid with a pKa of 3.27. In bile stabilized with 25% methanol, the precision of the method (CV) is 5% and the accuracy is 106-127%.
D001646:Bile / Q000378:metabolism; D001647:Bile Acids and Salts / Q000378:metabolism; D004386:Duodenum / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007208:Indocyanine Green / Q000378:metabolism*; D007700:Kinetics; D012709:Serum Albumin / Q000378:metabolism; D012997:Solvents
D001647:Bile Acids and Salts; D012709:Serum Albumin; D012997:Solvents; D007208:Indocyanine Green