Metrological evaluation of spectrophotometric and polarimetric methods in determining the griseofulvin content in the finished product

: Correctness and reproducibility of the results of spectrophotometric and polarimetric determinations of the griseofulvin content in the finished products were studied with the use of reference griseofulvin and the samples of the antibiotic industrial lots. It was shown that the relative standard deviation in determination of E1CM1% ranged within 1.6--4.6 per cent. The use of a greater number of the analytical wave lengths and special spectrophotometric methods for the assay of the substance in the presence of the admixtures resulted in significant systemic errors and did not improve the assay reproducibility. The relative standard deviation in determination of the specific rotation of 1 per cent solution of the drug in dimethyl formamide was about 0.6 per cent with the use of the same samples, no systemic errors higher than 1--2 per cent being observed. It is concluded that the use of the polarimetric method for quantitative determination of griseofulvin is more advisable.