c Sttek Mu Lire 22 6 LINC he a ee er ee ea oy DPA umnown isotone and the intercept of the line with the wero abacrber axis represents the relative amount of that isotope present in a mixture, The advantaze of this method lies in its applicability to low counting levels. This is possible because the line slope can be determined from light absorbers rather than the heavy absorbers required for Feather analyses. Tne method is in tentative use for isotope characterization for mixtures of isotopes and should be applicable to determination of Sr®?/2° ratios. mee Cf UNCLASSIFIED