SPECTROPHOTOMETRIC DETERMINATION OF PYROCATHECOL AND PYROGALLOL BASED ON THEIR REDOX REACTION WITH IRON(III)/PHENANTHROLINE SYSTEM - Mudasir, Mudasir; Department of Chemistry, Faculty of Mathematics and Natural Sciences, Gadjah Mada University, Sekip Utara, P.O. Box Bls. 21, Yogyakarta 55281 (Universitas Gadjah Mada, 2010)