Simultaneous determination of tryptophan and tyrosine in binary mixture by zero-crossing second derivative spectrophotometry.

Rapid and accurate binary mixture resolution of tryptophan and tyrosine was performed.differential-derivative spectrophotometry with a zero-crossing measurement technique was used for the quantitative determination of tryptophan and tyrosine in laboratory-prepared mixtures. neither sample pretreatment nor separation were required. linear calibration graphs of differential second derivative values were (at 222.4 and 217.9 nm for tryptophan and tyrosine , respectively) versus concentration in the ranges 0.1–20.0 and 1.0– 50.0 μg ml_1, and the linearity was satisfactory (r = 0.9987 and r = 0.9997), for tryptophan and tyrosine , respectively) were obtained .the relative standard deviations were found to be less than 1.03%, indicating reasonable repeatibility of method.the results obtained by the proposed method has been statistically compared by means of student t-test and by the variance ratio f-test where shows a good agreement .