Determination of Metformin Hydrochloride Assay According to USP

Metformin is one of the most commonly used drugs in the treatment of diabetes type 2. It is a biguanide. This application note describes the assay of metformin hydrochloride in compliance with USP using acetic anhydride as solvent.

Sample

Pure metformin hydrochloride powder

Sample Preparation

No sample preparation necessary

Configuration

Solutions

Blank Determination

For the determination of the blank, 4 mL of formic acid and 50 mL of acetic anhydride are placed into a titration beaker. The stirred solution is then titrated with c(HClO₄) = 0.1 mol/L in glacial acetic acid until the equivalence point is passed. The volume at which the equivalence point is achieved corresponds to the blank value.  

Analysis of Samples

50 to 75 mg of metformin hydrochloride is weighed accurately into a titration beaker to which 4 mL formic acid is added. After complete dissolution, 50 mL of acetic anhydride is added. Following a pause of 30 seconds for mixing, the solution is titrated with c(HClO₄) = 0.1 mol/L in glacial acetic acid until the equivalence point is passed.

Parameters

Results

This information has been sourced, reviewed and adapted from materials provided by Metrohm AG.

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