A simplified method of preparing phosphoric acid for stable isotope analyses of carbonates

Abstract

In order to produce CO2 for stable isotope analyses (δ18O and δ13C), carbonate samples are commonly digested in phosphoric acid. The acid recipe here presented is based on phase shifting crystalline orthophosphoric acid of pro-analysis quality to a liquid state through heating, followed by pre-vacuum treatment during a start-up procedure before mass analyses for common acid bath preparation, or adding a small amount of phosphoric pentoxide for single drop equipments, respectively. This methodology results in a final acid concentration of 104%. Copyright © 2005 John Wiley & Sons, Ltd.