HPLC Determination of p-Xylene and Its Oxidation Products with Dual Wavelength Detector

HPLC was applied to the determination of p-xylene and its oxidation products with photo-diode array detector. Detection at 210 nm for p-toluic alcohol and p-xylene and 254 nm for other products were used. A better separation of the peaks was achieved by optimizing the eluent and elution gradient program. In addition, the ratio of acetonitrile was decreased to 20%-30%. Effect of solvent on 4-carboxybenzalaldehyde and p-toluic aldehyde was investigated by HPLC and GC-MS. Both 4-carboxybenzalaldehyde and p-toluic aldehyde could react with the solvent of methanol to generate acetals. Detection limits (3S/N) of the method found were ranged from 0.07 to 0.8 mg·L-1. Values of recovery of analytes found were in the range of 99.2%-100%, with RSD′s (n=6) less than 2.5%.