METHOD FOR SEPARATE DETERMINATION OF TRYPTOPHAN AND TYROSINE IN AQUEOUS SOLUTION

FIELD: analytical chemistry, namely processes for continuous fermentation of proteins at standard analysis of pharmaceutical preparation production. ^ SUBSTANCE: method comprises steps of preliminarily preparing aqueous solution of tryptophan and tyrosine at initial concentration 0.01 and 0.1 mg/ml respectively; adding to it lithium sulfate - crystalline salting out agent in quantity 20 -25 mass% in relation to quantity of aqueous solution of amino acids; agitating till complete dissolving of salt; adding to prepared aqueous -salt solution of tryptophan and tyrosine extragent - preliminarily prepared mixture of hydrophilic solvents at volume relation of aqueous-salt solution and extragent mixture 10 : 1 , while preparing mixture of hydrophilic solvents from 60 mass % of butyl alcohol and 40 mass% of acetone; then extracting mixture in vibration mixer for 5 min; curing for 1 - 2 min; separating extract; determining content of tryptophan and tyrosine by potentiometer titration. In order to realize differential diagram of relationship of solution EMF change depending upon volume of added titrant is plotted. Such diagram has two maximums. First maximum corresponds to titrant volume used for titration of tyrosine and second maximum corresponds to total content of aminoacids in solution. Extraction degree of tryptophan and tyrosine is calculated by means of formula R = D - 100/D + r where D -distribution coefficient of tryptophan and tyrosine between binary mixture of hydrophilic solvents and aqueous-salt solution; R - relation of volumes of aqueous and organic phases. Method allows to determine up to 97 -98% of tryptophan and up to 98 -99% of tyrosine. ^ EFFECT: enhanced efficiency of method of determining tryptophan and tyrosine in aqueous solution with use of extraction by means of binary mixture of hydrophilic solvents. ^ 2 notes, 1 tbl