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Short communication
F A Mohamed1, A I Mohamed, S R El-Shabouri
1Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Assiut University, Assiut, Egypt.
Journal of Pharmaceutical and Biomedical Analysis
|January 1, 1988
Summary
A new calorimetric method accurately determines 10 sulphonamides and sulphamethoxazole-trimethoprim combinations. This rapid technique uses phenothiazine and N-bromosuccinimide for analysis without prior separation.
Area of Science:
- Analytical Chemistry
- Pharmaceutical Analysis
Background:
- Sulphonamides are crucial antimicrobials.
- Accurate quantification of sulphonamides in pharmaceutical formulations is essential for quality control.
Purpose of the Study:
- To develop a simple, rapid, and accurate calorimetric method for determining sulphonamides.
- To analyze sulphonamides as single entities and in combination with trimethoprim without prior separation.
Main Methods:
- A colorimetric reaction involving sulphonamide, phenothiazine, and N-bromosuccinimide at pH 6.
- Measurement of the blue colored product at 605 nm after acidification.
- Optimization of reaction variables including reagent concentrations, time, and pH.
Main Results:
- The method demonstrated adherence to Beer's Law for all analyzed sulphonamides.
- Successful application to pharmaceutical formulations (tablets, ophthalmic solutions) with high accuracy (96.7-100.67% of labelled claim).
- A strong correlation (r=0.9005) was found between molar absorptivities and pKa values of the sulphonamides.
Conclusions:
- The developed calorimetric method is simple, rapid, and suitable for the quantitative determination of sulphonamides.
- This method offers a reliable alternative for quality control of sulphonamide-containing pharmaceutical products.
- The correlation with pKa values suggests a predictable spectrophotometric behavior for these compounds.