Rapid HPTLC Quantification of p-Aminobenzoic Acid in Complex Pharmaceutical Preparations

A particularly rapid HPTLC method has been established for chromatographic separation and quantification of p-aminobenzoic acid (PABA) in complex dietary supplement tablets. After chromatography, PABA was determined by spectrodensitometry at 270 nm. PABA spots were then visualized by a novel staining procedure involving the Bratton-Marshall coupling reaction after spraying with 8-hydroxyquinoline in situ on the chromatographic plates. After visualization, spectrodensitometric analysis was repeated at 500 nm. Linearity, intermediate precision, sensitivity, accuracy, and precision were compared for both methods. Results from tablet analysis were verified with the modified Bratton-Marshall spectrophotometric procedure.