A simple, rapid, sensitive and reproducible fluorometric method for determi
ning microamount protein is developed. The method is based on the reaction
between protein and Indigo Carmine (IC) in an aqueous solution, which resul
ts 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 CB
B G-250 method. (C) 2001 Elsevier Science B.V. All rights reserved.