Spectrophotometric determination of sulfanilamide using PMDA as a π-acceptor: method optimization, validation, and...

Area of Science:

• Analytical Chemistry
• Spectrophotometry
• Computational Chemistry

Background:

• Sulfanilamide is a key sulfa drug with importance in pharmaceutical analysis.
• Accurate and precise quantification methods are crucial for drug quality control.
• Charge-transfer complexation offers a promising avenue for spectrophotometric analysis.

Purpose of the Study:

• To develop a novel, rapid, economical, and precise spectrophotometric method for sulfanilamide determination.
• To investigate the charge-transfer complex formation between sulfanilamide and pyromellitic dianhydride (PMDA).
• To elucidate the electronic interactions and mechanism governing the complex formation using DFT calculations.

Main Methods:

• Spectrophotometric analysis of sulfanilamide-PMDA charge-transfer complex.
• UV-Vis spectroscopy to determine maximum absorption wavelength and Beer's law compliance.
• Mole ratio method to ascertain complex stoichiometry and stability constant.
• Density Functional Theory (DFT) calculations for mechanistic insights.

Main Results:

• The method exhibited maximum absorption at 258 nm, adhering to Beer's law in the 0.2-35 μg mL⁻¹ range.
• High accuracy (101.501% recovery) and precision (<0.6% RSD) were achieved.
• A 1:1 complex stoichiometry with a stability constant of 2.49 × 10⁸ L mol⁻¹ was determined.
• DFT analysis confirmed the electron donor-acceptor mechanism involving sulfanilamide and PMDA.

Conclusions:

• A validated, efficient spectrophotometric method for sulfanilamide quantification was successfully developed.
• The study provides a mechanistic understanding of the sulfanilamide-PMDA charge-transfer complex.
• This method offers a valuable tool for the accurate and precise determination of sulfanilamide in pharmaceutical samples.