Determination of total sulfur contents in the international rock reference material SY-2 and other mafic and ultramafic rocks using an improved scheme of combustion/iodometric titration

An extensively modified combustion/iodometric titration method was used for the determination of sulfur in SY-2, a CANMET international rock reference material, in coarse-grained mantle rocks and glassy materials at the microgram level. Replicate analysis (n = 27) of SY-2 demonstrated the potential for this sample to be certified as a reference sample for S. Our mean sulfur concentration (122 +/- 3 mu g g(-1)) suggests that the recommended value (0.011% w/w) could underestimate the true value by 10%. The other results compare well with those generated by other more sophisticated techniques such as X-ray fluorescence spectrometry and electron probe microanalysis, whether S is dissolved in glassy materials or occurs as discrete sulfides.