ABSOLUTE ISOTOPIC ABUNDANCE AND ATOMIC WEIGHT OF A REFERENCE SAMPLE OF SILVER.

Abstract

The atomic weight of a reference sample of silver has been determined by mass spectrometry, with an uncertainty of one part in 10**6, using a single filament silica gel procedure. Accurately known quantities of chemically pure **1**0**7Ag and **1**0**9Ag were mixed to produce standards of known isotopic composition for calibration of the mass spectrometer. The absolute isotopic ratio of the reference sample of silver is **1**0**7Ag/**1**0**9Ag equals 1. 07638 plus or minus 0. 00022 yielding an atomic weight of 107. 86815 plus or minus 0. 00011. The indicated uncertainties represent an overall limit of error at the 95 percent confidence level which is the sum of the uncertainty components for the ratio determined and the components covering effects of known sources of possible systematic error.