Hi, I have been searching for detailed protocols on determination of ion exchangeable rare earths in ion adsorption ore. The method I currently used is by titration against EDTA using xylenol orange disodium salt as indicator (0.1g dissolved in 100ml water) with ammonium acetate as buffer to maintain pH 5. I still has doubt with the results obtained. Could anyone provide me with detailed references for this protocol? Thank you very much.