Glassy tin arsenate, Sn(HAsO4)2·2.7H2O (SnAs) was prepared and characterized. The uptake of lanthanide ions La3+, Sm3+, Eu3+, and Yb3+ was followed on the glassy tin arsenate in HNO3 solution at pH 1,2 and 4. The radiotracers are140La,153Sm,152mEu, and175Yb. 500 μl (4.0·10−5 mmole) of each solution of the tracer as a mixture plus 7.5 ml HNO3 solution at the desired pH were equilibrated with 0.1g of SnAs. The selectivity order (Kd values) was found to be dependent on the pH. At pH 2 theKd values were high for all the studied metal ions [Yb (2065.4)>La (1976.1)>Sm (1826.4)>Eu (1754.4)]. TheKd values at pH 1 and 4 are quite low for all the metal ions studied. At pH 1 they range from ≈144 to 156 and at pH 4 they range
from ≈70 to 79.