Simply because you will discover similarities in between arsenic acid and phosphoric acid, the likelihood that arsenate can swap the important phosphate group in biologically essential molecules (like the monosaccharide phosphates and adenosine triphosphate) have to be thought of. During the processing of As2O3 the oxide is Typically minimized withcarbon: https://simonpibtl.mappywiki.com/1299640/arsenic_lll_oxide_fundamentals_explained