Semimicro-titrimetric method for the determination of activity-concentration of heparin

A semimicro-titrimetric method for the determination of heparin is developed. The method depends upon the determination of the sulphate content of the acid drolysate of heparin by adding an excess of barium chloride and back titration with standard sulphuric acid, using sodium rhodizonate as indicator. The method measures the biological activity of 10-50 mg of heparin, with a mean accuracy (p = 0.05) 99.73 +/-0.81%. Application of the proposed method for the determination of heparin in some pharmaceutical preparations is carried out by precipitation of the intact heparin molecule with cetyltrimethylammonium bromide, ashing of the precipitate and determination of its sulphate content; alkaline and acid degradation products do not interfere with the proposed procedure.