Thin Layer Chromatography Identification Test for Dextromethorphan following European Pharmacopeia Monograph on Silica Gel G 254 Plates

European Pharmacopoeia monograph method

Introduction

Dextromethorphan is a drug of the morphinan class.
It is a cough suppressant with sedative, dissociative, and stimulant properties (at higher doses) and it is the active ingredient in many over-the-counter cold and cough medicines.

This application note illustrate how Silica Gel G plates are suitable for the analysis of Dextromethorphan following the European pharmacopeia identification TLC test experimental conditions (version 9.0).

Dextromethorphan Hydrobromide

Dextromethorphan Hydrobromide

 

Experimental Conditions
TLC Plate Silica Gel 60G F254  20 x 20 cm   Injection volume 5 µL
Detection Spray with potassium iodobismuthate solution R2 (Potassium iodobismuthate solution: Suspend 1.7 g of bismuth subnitrate R and 20 g of tartaric acid R in 40 mL of water R. To the suspension add 40 mL of a 400 g/L solution of potassium iodide R and stir for 1 h. Filter. The solution may be kept for several days in brown bottles. Mix immediately before use 5 mL of the stock solution with 15 mL of water.    
Mobile Phase Concentrated ammonia: methanol : methylene chloride : ethyl acetate : toluene  2:13:10:20:55 (v/v/v/v/v )    
Plate development Spot the plate with the standard and sample solution and dry the plate for few minutes and place the plate in an unsaturated tank containing a mixture of concentrated ammonia : methanol : methylene chloride  1:20:80 (v/v/v).    
Development   Over 2/3rd of the plate
Diluent Methanol
Drying In air
Standard Dissolve 25 mg of standard timolol maleate in methanol  and dilute
to 10 ml with the same solvent
Sample Dissolve 25 mg substance to be examined in methanol and dilute
to 10 ml with the same solvent .

 

TLC plate development

TLC plate development

 

Chromatograms

Chromatograms

 

Spectrum

Spectrum

 

Chromatographic Data (Standard Solution)

Chromatographic Data (Standard Solution)

 

  Compound Rf
1 Dextromethorphan 0.29

Chromatographic Data (Sample Solution)

Chromatographic Data (Sample Solution)

 

  Compound Rf
1 Dextromethorphan 0.29

 

Standard Repeatability
STD 1 2363
STD 2 2347
STD 3 2494
STD 4 2453
STD 5 2461
Mean 2423.6
Standard Deviation 64.7
RSD (%) 2.7

 

  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.
  2. All the spots for the reference solution have a repeatability better than 3% RSD.
  3. Merck silica gel G plates provides repeatable and reproducible results for Dextromethorphan identification test and comply to all requirements as per European Pharmacopoeia.

 

Materials

     
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