Improved thermal decomposition of sulfates to SO2 and mass spectrometric determination of delta S-34 of IAEA SO-5, IAEA SO-6 and NBS-127 sulfate standards

We describe a significant improvement to our low-temperature thermal decomp osition of sulfates to SO2 for isotopic analysis (Halas S, Szaran J. Anal. Chem. 1999; 71: 3254) that has led to better reproducibility and efficiency of measurements. In the present approach we use a mixture of two reagents, NaPO3 + V2O5, mixed in a weight ratio of 3:5. The addition of V2O5 prevent s overboiling of NaPO3 at temperatures, T, increased to 800 degreesC. Using this modified method we obtained the following delta S-34 values (in parts per thousand): +21.17 +/- 0.12 for NBS-127, +0.15 +/- 0.06 for IAEA SO-5, and -34.12 +/- 0.11 for IAEA SO-6. Copyright (C) 2001 John Wiley & Sons, Lt d.