Field screening test for iron leached from well bore rock samples by usingcolor development of iron(III)-xylenol orange system

A field test for iron leached from rocks has been developed by using a purp le blue iron(III)-Xylenol Orange (XO) complex formed at the iron(III) conce ntrations above the molar concentration of XO. The test is performed in an aqueous drop on a Tefron(R) plate. When the iron content exceeds a criterio n, a distinct color change from yellow to purple blue appears in the drop c ontaining a 10-mg rock sample, HCl, XO, and (NH4)(2)S2O8. This method was a pplied to the prediction of water quality in aquifers.