[Extraction and polarimetric method of determining phenacetyl-D(-)-alpha-aminophenylacetic acid].

Equilibrium distribution of phenacetyl-D-(--)-alpha-aminophenylacetic acid obtained on fermentative hydrolysis of D,L-aminophenylacetic acid in a two-phase system (chloroform-water) was studied within a wide range of the substance concentration in the organic phase. It was shown than in the organic phase the distributing substance formed associates. The empirical equation: y = A + Bx describing the dependence of the effective distribution of the non-dissociated form of phenylacetyl-D-(--)-alpha-aminophenylacetic acid on its concentration in the organic phase was suggested. Coefficients A and B of the equation were determined and an equation for evaluating equilibrium concentrations in the equeous phase was suggested. On the basis of the studies an extraction-polarometric method for quantitative determination of phenacetyl-D-(--)-alpha-aminophenylacetic acid concentration was developed. The method consists of extraction of the non-dissociated form of phenylacetyl-D-(--)-alpha-aminophenylacetic acid with chloroform, determination of the equilibrium concentration of the distributing substance in the organic phase by the polarimetric method and subsequent estimation of the equilibrium and initial concentrations of the electrolyte in the aqueous phase.