Determination of the potency of sodium heparin injection using Thionin I_660

The potency of sodium heparin injection was determined by using Azure I. Experiments showed that heparin reacts sensitively with Azure I in most buffer solutions at pH 6-8, but with little response outside this range. Therefore, distilled water was used as the medium in this method. However, due to the significant effect of medium acidity on the decrease in absorbance after the reaction between Azure I and heparin, a control method rather than a standard curve method was adopted.

3.2 The kmax of Azure I is not affected by the medium's acidity. In different pH mediums, kmax remains consistently at 633nm.

3.3 Since this method utilizes the reduction in Azure I's absorbance for determination, it is appropriate for the absorbance of the Azure I control solution to be approximately 0.8.

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