Fluorescent detection of 0-quinones formed in lignin-containing pulps during irradiation
1995
Zhu, J.H. | Olmstead, J.A. | Gray, D.G.
omicron-Quinones are thought to play a key role in the photoyellowing of mechanical pulps. The facile reaction between omicron-quinones and phenylenediamine to give fluorescent phenazines is examined as a possible way to detect quinonoid intermediates in pulp sheets. The method was tested on omicron- quinone-rich mechanical pulp sheets prepared by chemical treatment with Fremy's salt (potassium nitrosodisulphonate). The presence of photochemically generated omicron-quinone groups in peroxide-bleached mechanical pulps was inferred from the fluorescence observed from omicron-phenylenediamine treated sheets. This fluorescence increased with increasing radiation time up to a limiting value. The quinones (but not their phenazine dervatives) are stable upon storage in the dark.
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