Field Screening Test for Iron Leached from Well Bore Rock Samples by Using Color Development of Iron(III)-Xylenol Orange System

A field test for iron leached from rocks has been developed by using a purple blue iron(III)-Xylenol Orange (XO) complex formed at the iron(III) concentrations above the molar concentration of XO. The test is performed in an aqueous drop on a Tefron® plate. When the iron content exceeds a criterion, a distinct color change from yellow to purple blue appears in the drop containing a 10-mg rock sample, HC1, XO, and (NH4)2S2 O8. This method was applied to the prediction of water quality in aquifers.