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Ion exchange separation of chromium from natural water matrix for stable isotope mass spectrometric analysis

J.W. Ball·R.L. Bassett
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Abstract

A method has been developed for separating the Cr dissolved in natural water from matrix elements and determination of its stable isotope ratios using solid-source thermal-ionization mass spectrometry (TIMS). The separation method takes advantage of the existence of the oxidized form of Cr as an oxyanion to separate it from interfering cations using anion-exchange chromatography, and of the reduced form of Cr as a positively charged ion to separate it from interfering anions such as sulfate. Subsequent processing of the separated sample eliminates residual organic material for application to a solid source filament. Ratios for 53Cr/52Cr for National Institute of Standards and Technology Standard Reference Material 979 can be measured using the silica gel-boric acid technique with a filament-to-filament standard deviation in the mean 53Cr/52Cr ratio for 50 replicates of 0.00005 or less.

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J.W. Ball, R.L. Bassett. 2000. Ion exchange separation of chromium from natural water matrix for stable isotope mass spectrometric analysis. https://doi.org/10.1016/s0009-2541(00)00189-3

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