Determination of para-aminobenzoic acid (PABA) in BB-complex tablets using the Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS) method

The para-aminobenzoic acid (PABA) product is an amphoteric component that has three forms in an aqueous solution. PABA can titrate with strong acid or a strong base. The conjugated acid of PABA can ionize in two sections, and two peaks can be detected to overlap. In this situation, the correct resolution and quantitation of the analytes is not possible, An UV spectrophotometric acid-base titrations method is proposed for the quantitative determination of PABA products in pharmaceutical samples. The acid-base equilibrium model is included in the Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS) method. This method makes data evaluation possible, even when spectra of contributing substances are highly overlapping or reaction intermediates have to be detected. Furthermore, quantification of analytes is possible in the presence of unknown interferents if pure analyte standards are available. The results obtained indicate a recovery of >91% and relative error of <9% in the proposed approach for the PABA product.