“If a commercial aspirin tablet is properly hydrolyzed and complexed with iron(III), its absorbance at λmax (~530 nm) will correlate to a concentration of salicylic acid that, when back-calculated, confirms the labeled 325 mg of ASA.”

Spectrophotometric analysis determines the acetylsalicylic acid content in aspirin tablets by measuring the absorbance of a violet-colored iron(III)-salicylate complex, using Beer-Lambert's Law to relate absorbance to concentration. The process involves generating a calibration curve from standards to calculate the experimental mass and percentage error compared to the label claim. Access the full report at clame.nyu.edu New York University

Direct analysis of ASA is difficult due to its low absorptivity and tendency to hydrolyze slowly. Therefore, complete hydrolysis was induced.