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Use of differential scanning potentiometry in pharmaceutical analysis
R H Manzo1, E Luna, D A Allemandi
1Departamento de Farmacia, Facultad de Ciencias Quimicas, Universidad Nacional de Córdoba, Argentina.
Journal of Pharmaceutical Sciences
|January 1, 1991
Summary
Differential scanning potentiometry (DSP) offers a superior method for analyzing pure drugs and mixtures, providing insights into identity, purity, and pKa values. This technique excels in assaying small samples and those with weak acidic or basic groups compared to traditional methods.
Area of Science:
- Analytical Chemistry
- Pharmaceutical Analysis
- Electrochemistry
Background:
- Accurate assessment of drug identity, purity, and ionization properties is crucial in pharmaceutical analysis.
- Conventional potentiometric methods can be limited in assaying small sample volumes or complex mixtures.
- Developing novel analytical techniques for enhanced drug characterization is an ongoing need.
Purpose of the Study:
- To demonstrate the application of differential scanning potentiometry (DSP) for the quantitative analysis of pure drugs and mixtures.
- To evaluate the efficacy of DSP in determining drug identity, chemical purity, and pKa values.
- To compare the performance of DSP with conventional aqueous acid-based potentiometry.
Main Methods:
- Differential scanning potentiometry (DSP) was employed to analyze model drug compounds including glycine, sulfanilamide, epinephrine, and norfloxacin.
- DSP was also utilized to determine the degree of hydrolysis in a parenteral solution of procaine hydrochloride.
- Analysis involved scanning drug samples and quantifying peak areas (A+, A-, and At) to assess assay parameters.
Main Results:
- DSP successfully generated characteristic profiles for pure drugs, yielding quantifiable areas (A+, A-, and At) useful for identity and purity assessment.
- The pKa values of ionizing groups within the analyzed drugs were determined using DSP.
- DSP accurately quantified the degree of hydrolysis in a procaine hydrochloride mixture, demonstrating its capability for mixture assay.
Conclusions:
- Differential scanning potentiometry (DSP) is a powerful and versatile technique for the assay of pure drugs and complex mixtures.
- DSP provides valuable information regarding drug identity, chemical purity, and ionization characteristics (pKa).
- DSP significantly outperforms conventional potentiometry for the analysis of small sample sizes and compounds with weak acidic/basic functionalities.