The spectrophotofluorometric determination of tryptophan in plasma and of tryptophan and tyrosine in protein hydrolysates.

A spectrophotofluorometer capable of continuous activation of solutions and measurement of resultant fluorescence throughout the quartz-ultraviolet and visible regions of the spectrum has been previously described (1). The ability of such an instrument to deliver high intensity monochromatic light at the absorption maxima of tryptophan and tyrosine, and to measure the resulting ultraviolet fluorescence spectra, provides the basis for a simple and extremely sensitive method for the determination of these amino acids in tissues and in protein hydrolysates.