Related Experiment Video
Updated: Jan 2, 2026

High Precision Zinc Isotopic Measurements Applied to Mouse Organs
Published on: May 22, 2015
Absolute Isotopic Abundance Ratios and the Atomic Weight of a Reference Sample of Chromium
William R Shields1, Thomas J Murphy1, Edward J Catanzaro1
1Institute for Materials Research, National Bureau of Standards, Washington, D.C.
Abstract:
Absolute values have been obtained for the isotopic abundance ratios of a reference sample of chromium, using surface emission mass spectrometry. Samples of known isotopic composition, prepared from nearly pure separated chromium isotopes, were used to calibrate the mass spectrometers. The resulting absolute values are Cr50/Cr52 = 0.051859 ±0.000100, Cr53/Cr52 = 0.113386 ±0.000145, Cr54/Cr52 = 0.028222 ±0.000059, yielding an atomic weight (CI2=12) of 51.99612 ±0.00033. The indicated uncertainties arc overall limits of error based on 95 percent confidence limits for the mean and allowances for effects of known sources of possible systematic error.
Related Concept Videos
Atomic Mass
Atomic Weight
Mass Spectrometry: Isotope Effect
High-Resolution Mass Spectrometry (HRMS)
Atomic Absorption Spectroscopy: Lab
Solutions containing organic solvents, such as low-molecular-mass alcohols, esters, or ketones, enhance absorbances by increasing...
Chemical Shift: Internal References and Solvent Effects
The internal reference compound generally used in NMR spectroscopy is tetramethylsilane (TMS). TMS is preferred because it is chemically inert, soluble in NMR solvents, and easily removable. Also, the highly shielded methyl protons in TMS yield an intense...

