The extractant system in Eichrom's Sr Resin is 1.0M 4,4'(5')-di-t-butylcyclohexano 18-crown-6 (crown ether) in 1-octanol.A 40% (w/w) loading of this organic solution is loaded onto an inert chromatographic support. The bed density of Sr Resin is approximately 0.35 g/mL.