Metformin Hydrochloride European Pharmacopoeia Identification Test C using Silica gel G TLC Plates

By: Dr Sanjay Poman, Merck KGaA, Darmstadt, Germany, Life Science Application Centre (GAC), Mumbai, India


Metformin Hydrochloride is primarily used for treatment of type 2 diabetes, but is increasingly being used in polycystic ovary syndrome.

Current European pharmacopoeia (version 9.5) indicates that a TLC silica gel G plate should be used for the Metformin Hydrochloride identification test C. TLC silica gel G plate complies with the requirements for a TLC silica gel plate R but with the following modification, it contains calcium sulfate hemihydrate as binder. In this application note we elaborate how Silica Gel G plates can be used for this test.

Metformin Hydrochloride

1,1– Dimethylbiguanide hydrochloride


Experimental Conditions
TLC Plate Silica Gel 60G F254  20x20 cm   Injection volume 5 µL
Detection Spray with a mixture of equal volumes of 100 g/L sodium nitroprusside, 100 g/L potassium ferricyanide and 100 g/L of sodium hydroxide. Prepared the solution 20 minutes before use.    
Mobile Phase Glacial acetic acid:Butanol:Water 10:40:50  (v/v/v) use upper layer.    
Plate development Prewash the plate in methanol and allow to dry in air before use. Use mobile phase described above. Spot standard and sample . Develop the plate for 15 cm.Remove the plate dry in air, spray with 5 g/L potassium ferricyanide in ferric chloride Examine in day light.    
Development   Over 2/3rd of the plate
Diluent Water
Drying At 100 Degree centigrade for 15 minutes
Standard Dissolve 20 mg of Metformin Hydrochloride CRS in water and dilute to 5 mL with the same solvent.
Sample Dissolve 20 mg of substance to be examined in water and dilute to 5 mL with the same solvent


TLC Plate after development




Chromatographic Data (Standard Solution)


Chromatographic Data (Standard Solution)



  1. The principal spot in the chromatogram obtained with the test solution is similar in position, but less intense colour and somewhat smaller size to the principal spot in the chromatogram obtained with the reference solution.
  2. Silica gel G plates can be used for the Metformin Hydrochloride European Pharmacopoeia identification test C, using butanol, glacial acetic acid and water as solvents, and where all other listed products also comply to set requirements.