High-Performance Liquid Chromatography Using Ultraviolet Detection for Separation of Terephthalic Acid and Associated Impurities from Recycled Materials.

The article focuses on the development and validation of an optimized reversed-phase high-performance liquid chromatography (RP-HPLC) method for the rapid, precise separation, identification, and quantification of eight acidic impurities in recycled terephthalic acid (TPA). Using a Waters X-Select HSS T3 column and a mobile phase containing 0.1% trifluoroacetic acid (TFA), the method achieves baseline separation of all compounds within 17 minutes, with improved peak shapes and resolution attributed to suppression of analyte ionization via mobile phase acidity tailored to analyte pKa values. The study compares standard addition and external calibration quantification approaches, finding comparable results even at low impurity concentrations below 10 ppm, and addresses key validation parameters including sensitivity, selectivity, linearity, limit of detection, and quantitation. This method meets the criteria of the QuEChERS approach—quick, easy, cheap, effective, rugged, and safe—offering a viable analytical tool for quality control of recycled TPA used in polyester production.