[Polarographic assay of nicotinic acid in the culture liquid].

The method of potarographic assay of nicotinic acid in the culure liquid has been developed. The effect of all the constituents of the culture liquid on the accuracy of measurements has been tested. The analytic scheme which provides elimination of interfering components has been devised. As the polarographic medium 0.1 n HCl was used. The quantity of nicotinic acid was measured with respect to the wave of E1/2 = - 1.18 v. The described method makes it possible to identify nicotinic acid at concentrations of 3.3 X 10(-4) M to 3.3 X 10(-3) M in the culture liquid with an error of not more than +/-5%.