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

In order to produce CO2 for stable isotope analyses (delta O-18 and delta C-13), 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 (C) 2005 John Wiley & Sons, Ltd.