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Water determination in drugs containing thiols
1The National Physical Laboratory of Israel, Givat Ram, Jerusalem, Israel.
International Journal of Pharmaceutics
|November 5, 1999
Summary
A novel analytical method accurately determines water and thiol content in pharmaceutical tablets. This rapid technique overcomes limitations of standard Karl Fischer titration for thiol-containing compounds.
Area of Science:
- Analytical Chemistry
- Pharmaceutical Analysis
Background:
- Thiol-containing compounds like alpha-Mono-thioglycerol and Captopril present challenges for direct Karl Fischer titration due to thiol interference.
- Accurate water content determination is crucial for pharmaceutical quality control and drug stability.
Purpose of the Study:
- To develop and validate a rapid analytical method for simultaneous water and thiol determination in pharmaceutical formulations.
- To provide a reliable alternative to conventional Karl Fischer titration for thiol-containing samples.
Main Methods:
- A novel consecutive titration approach was employed using a single sample and cell.
- The method involves initial titration of thiol using a new reagent (iodine, potassium iodide, sodium acetate in non-aqueous medium).
- Subsequent titration of water is performed using a conventional Karl Fischer reagent with electrometric 'dead-stop' endpoint detection for both titrations.
Main Results:
- The developed method demonstrated satisfactory repeatability and accuracy for both water and thiol content determination.
- The analytical procedure is rapid and suitable for routine quality control of pharmaceutical products.
Conclusions:
- The new consecutive titration method effectively quantifies water and thiol in challenging pharmaceutical matrices.
- This approach offers a robust and efficient solution for the analysis of thiol-containing drugs, improving analytical capabilities in pharmaceutical quality assurance.