EXTRACTION AND SPECIATION OF CHROMIUM(VI) AND CHROMIUM(III) AS ION-ASSOCIATION COMPLEXES OF TETRAMETHYLAMMONIUM-CHROMATE - Wandoyo, Valencia Widiyaningrum; Department of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Gadjah Mada, Sekip Utara PO. Box BLS 21 Yogyakarta 55281 (Universitas Gadjah Mada, 2010)