DETERMINATION OF PEROXYACETIC ACID USING HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY WITH EXTERNAL CALIBRATION

A new method for the determination of peroxyacetic acid (PAA) in aqueo us solutions is described. Methyl p-tolylsulfide (MTS) is oxidized by PAA, forming the corresponding methyl p-tolylsulfoxide sulfoxide (MTSO ), which can be separated easily by high-performance liquid chromatogr aphy on a reversed-phase column and detected by ultraviolet spectrosco py at a wavelength of 230 nm. MTSO is a commercially available solid s ubstance which can be used as an external standard for calibration. Th erefore, calibration with the unstable PAA can be avoided. This method is characterized by a high reproducibility, low detection limits at 4 x 10(-7) mol/L (30 mu g/L), an applicable concentration range of more than two decades, and negligible cross reactivity toward hydrogen per oxide.