Determination of peroxygen species present in pulp fiber matrixes.

A new chromatographic method for the determination of oxidants, such as peroxyborates and peroxides, present in a pulp matrix has been developed. The new method is characterized by its high reproducibility, its low limit of detection, and its high selectivity. Thioanisole (methylphenyl sulfide) is shown to selectively and quantitatively react with oxidants that are present within a pulp matrix. The experimental protocol proposed requires an HPLC system with a normal-phase column. The method allows for the quantitative monitoring of the thioanisole starting material, as well as the products of oxidation, methylphenyl sulfoxide and methylphenyl sulfone. After a 2-day reaction period, the analysis time for a sample is less than 20 min. The detection limit is 2.7 × 10(-6) M for the sulfoxide and sulfone and less than 5.0 × 10(-7) M for the thioanisole. This novel approach for monitoring oxidants present on solid lignocellulosic matrixes may provide pulp and paper manufacturers with a new tool for the study of the long-term bleaching effectiveness of peroxy-containing chemical additives.