Heparin assay: a comparison between titrimetric and amidolytic methods.

Titration assay of heparin with protamine sulfate permits the quantitative measurement of the concentration of the heparin molecule; on the contrary, the amidolytic method allows only a determination of the biological activity of heparin because it is subjected to the interferences of antiheparin factors. These may even be assayed with the amidolytic method by the evaluation of the residual activity after the addition to plasma of known amounts of heparin. The combined used of the two methods may prove useful in the assessment of concentration and specific activity of unknown heparin solutions in mediums free of antiheparin activities.