INTRODUCTION

These test methods cover the determination of 4-carboxybenzaldehyde (4-CBA, 4-formylbenzoic acid) and p-toluic acid (p-TOL, 4-methylbenzoic acid) in purified terephthalic acid (PTA) by capillary electrophoresis (CE) with normal or reverse voltage mode and UV detection.

MEASUREMENT METHOD

The measurement methods are based on capillary zone electrophoresis with direct UV detection at the wavelength of 200 nm.