A fluorometric method for the specific determination of serum arginine with 2,3-naphthalenedicarbaldehyde

A specific and simple fluorometric method for the determination of serum arginine was developed which consists of (1) deproteinization of serum sample with 10% perchloric acid, (2) blocking thiol compounds with N-ethylmaleimide, (3) fluorescence reaction with 2,3-naphthalenedicarbaldehyde in 0.2 M borate buffer, pH 9.3, in the presence of beta-cyclodextrin (25 min at 20 degrees C, excitation wavelength: 462 nm, emission wavelength: 520 nm). Since the fluorescence reaction is highly specific for arginine, the method requires no other separation step. Linearity, recovery, and reproducibility of the method were found to be satisfactory.