Fluorometric method for the microdetermination of protein using indigo carmine

A simple, rapid, sensitive and reproducible fluorometric method for determining microamount protein is developed. The method is based on the reaction between protein and Indigo Carmine (IC) in an aqueous solution, which results in a long-wave fluorescence emission (lambda (ex) = 690 nm, lambda (em) = 780 nm). The calibration curves of several proteins are given. Under the optimized experimental conditions, there is little interference from amino acids, some drugs, and most metal ions. rn the detection of total amount of proteins in human serum, this method gives values close to those of the CBB G-250 method. (C) 2001 Elsevier Science B.V. All rights reserved.