METHOD FOR DETERMINATION OF LYSINE IN AQUEOUS SOLUTION Russian patent published in 2007 - IPC G01N31/16 G01N27/48 

FIELD: analytical chemistry, amino acids.

SUBSTANCE: method involves preparing lysine aqueous solution in the concentration 0.01-0.1 mg/ml, addition of crystalline lithium sulfate as a desalting agent in the concentration 25 wt.-% to the lysine solution followed by stirring the solution and addition of mixture of hydrophilic solvents prepared from 50-60 wt.-% of isopropyl alcohol and 40-50 wt.-% of ethyl acetate. Extract is separated and the lysine content in extract is determined by method of potentiometric titration. The differential curve is built showing dependence of the medium potential from the titrating agent volume. The extraction degree (R, %) of lysine is calculated by the following formula: R = D^*100/D + r wherein D means the distribution coefficient of lysine between mixture of solvents and aqueous-saline solution; r means the ratio of equilibrium volumes of aqueous and organic phases. Method provides the possibility for determination of lysine concentration in aqueous solution with using a desalting agent and mixture of hydrophilic solvents. Invention can be used in development of processes in manufacturing foodstuffs containing biologically active supplements.

EFFECT: improved assay method of lysine.

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