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TLC method for Tetrabutylammonium fluoride content in a drug a substance
A bird’s eye view on method development approach:
- Molecular weight: C16H36FN
- Molecular weight: 261.46g/mol
Following is the structure of Tetrabutylammonium fluoride
Structure drawn in ACD/ChemSketch
From the structure, it is clear that it is a quaternary ammonium salt. It does not have any chromophore and secondly, it is an ionic compound. Therefore it will neither analyzed on HPLC nor on GC.
The only possibility is to develop a qualitative TLC method. That is why widely qualitative TLC method is used for its content in Pharmaceutical substances.
In the following TLC condition it is quantified up to 0.05% in the pharmaceuticals
TLC condition
- TLC plate: Silica Gel 60 F254
- TLC mobile phase: mixture of Dichloromethane and Methanol in the rat io of 88:12.
- TLC chamber: Vertical chamber saturated with 25% ammonium hydroxide solution
- Diluent: Dichloromethane
- Sample concentration: about 150mg/ml in Dichloromethane
- Standard: Tetrabutylammonium fluoride 0.05% ( weigh about 7.5 mg of Tetrabutylammonium fluoride and dilute to 100 ml with diluent)
- Injection volume: 5µl
- Run: about 10 cm
- Detection: iodine vapour about 25 to 30 minutes
TLC Procedure
Apply 5µl of each standard and sample solution on the TLC plate and allow the spot to dry. Place the TLC plate in the equilibrated TLC chamber. Run the mobile phase up to 10 cm on the plate. Allow the plate to dry at the room temperature in the hood. Then put the TLC plate in the iodine chamber for 25 to 30 minutes. Compare the spot of Tetrabutylammonium fluoride in the sample with standard Tetrabutylammonium fluoride .
Abbreviations
TLC: Thin layer chromatography