European Pharmacopoeia Method for Diclofenac Identification Test B using Silica Gel G TLC plates

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

Introduction

Diclofenac sodium is a non-steroidal anti-inflammatory (NSAID) drug. It is used to treat pain, inflammatory disorders, and dysmenorrhea.

Current European pharmacopoeia (version 9.5) indicates that a TLC silica gel GF254 plate should be used for the Diclofenac Sodium identification test B. TLC silica gel GF254 plate complies with the requirements for a TLC silica gel plate R but with the following modification, it contains calcium sulfate hemihydrate as binder and a fluorescent indicator having a maximum absorbance at 254 nm. The fluorescence suppression furthermore complies with the test prescribed for TLC silica gel F254 plate R.

In this application note we elaborate how Silica Gel G plates can be used for this test.

Experimental Conditions
TLC Plate Silica Gel 60G F254  20x20 cm  
Injection volume 5 µL

 

Detection
Examine in ultra violet light at 254 nm
Mobile Phase Concentrated ammonia:methanol:ethyl acetate 10:10:80 (v/v/v)
Plate development Examine under ultra violet light at 254 nm
Development Over ½ of the plate
Diluent Methanol
Drying In air
Standard a) Dissolve 25 mg of diclofenac sodium in methanol and dilute to 5 ml with methanol
b) Dissolve 10 mg of indometacin in reference solution and dilute to 2 ml with
    reference solution a (SST Solution)
Sample Dissolve 25 mg of substance  to be examined in methanol and dilute to 5 ml with the same solvent.

 

TLC Plate after development

TLC Plate after development

Chromatogram

Chromatogram
 

Chromatographic Data (SST Solution)

Chromatographic Data (SST Solution)
 

Compound Rf
Area
Indometacin 0.34 2818
Diclofenac sodium 0.38 2417

 

Chromatographic Data (Sample Solution )

Chromatographic Data (Sample Solution)
 

Compound Rf
Area
Diclofenac sodium 0.36 3065

Conclusion

  1. The principal spot in the chromatogram obtained with the test solution is similar in position, colour and size to the principal spot in the chromatogram obtained with reference solution (a).
  2. The System suitability criteria is met using reference solution (b) the chromatogram shows 2 clearly separated spots.
  3. Silica gel G plates together with LiChrosolv grade Ethyl acetate and Methanol can be used for the European Pharmacopoeia Diclofenac Sodium identification test B and all recommended products comply to set pharmacopeial requirements.

Materials