摘要
Santrock, Studley and Hayes emphasized in a recent paper on the isotopic analyses based on the mass spectrum of carbon dioxide the necessity of a direct measurement of the absolute abundance of 17O in V-SMOW. Utilizing a sample of 46O-water containing 99.991 479 atom% 16O, and the accurate value of R45,NBS-20=0.011 943（24）, previously determined for its liberated CO2, we have found R17,v-CMOW-0.000379 9（8）, corresponding to 0.03790（8） atom% 17O in V-SMOW,
