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Impurities Method for Metformin HCl Formulation
Simple separation of API from Melamine and Cyanoguanidine
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printable Application Sheet
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Sample: 100mg strength ground tablet was weighed in a 100 mL volumetric flask. Then 60 mL methanol was added and the flask was vortexed.
Mobile phase was then added to volume. The solution was filtered through a 0.45 µm nylon filter (MicroSolv Tech Corp.) The sample
for injection was diluted 1:100 with 50:50 solvent A:B mixture. Accuracy was demonstrated by spiking the sample with a known amount of
cyanoguanidine and melamine.
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Method Conditions
| Column |
Cogent Diamond Hydride™, 4µm, 100A |
| Catalog No. |
70000-15P-2 |
| Dimensions |
2.1 x 150 mm |
| Solvents |
| A: | 50% isopropanol/ 50% DI water/ 0.1% acetic acid |
| B: | Acetonitrile/ 0.1% acetic acid |
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| Gradient |
| time (min.) |
%B |
time (min.) |
%B |
| 0 |
100 |
9 |
20 |
| 2 |
100 |
10 |
100 |
| 5 |
20 |
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| Post Time |
5 min |
| Injection Vol. |
1 microL |
| Flow rate |
0.4 mL/min. |
| Detection |
ESI – POS - Agilent 6210 MSD TOF mass spectrometer |
| Peak |
1. Cyanoguanidine 85.0509 m/z (M +H)+
2. Melamine 127.0727 m/z (M +H)+
3. Metformin 130.1087 m/z (M +H)+ |
| t0 |
0.9 min |
Discussion
A simple method was developed for the analysis of the widely prescribed anti-diabetic drug metformin hydrochloride and for determination of two
impurities (cyanoguanidine and melamine) in tablet formulations. The method has the ability to separate metformin from its impurities. In
addition to accurate mass for all three compounds, the peaks were confirmed by injections of the standards. The USP-specified impurity limits
are not more than 0.02% and 0.01% for cyanoguanidine and melamine respectively.
The precision of this method was evaluated by calculating %RSD of the peak areas of five replicate injections (see Figure B). The obtained value
was 0.2%.
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