For attainment of near-intrinsic losses in the 2 to 4 µm range, concentrations of cations such as iron, cobalt, nickel, and copper must lie in the 0.2 to 10 ppb range (1 ppb = 1 mol/109 mol of glass). Commercial grades of zirconium salts tend to form colloids and to contain hundreds or thousands of times more than the tolerable concentrations. We have found filtration to be partially effective for colloid removal. Working with relatively concentrated (2 molar, about 17% by weight) solutions of Zr salts, we have introduced about 7000 ppb each of Fe, Co, Ni, and Cu. We have determined that all of these metals can readily be removed by laboratory-scale ion-exchange methods to meet the cation-purity standards for near-intrinsic absorption.