Sulfur Determination via Schoniger Combustion

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Atomic weight 32.06, Atomic Number 16, Melting Point 115.21 C, Boiling Point 444.67 C.

The solid sample is weighed into ashless paper and inserted into custom made Platinum stopper. The stopper is fitted it a flask that is charged with the appropriate reactants and oxygen. On combustion the sulfur present is oxidized from SO₂ to SO₃. The resulting liquid is then removed and titrated. With an indicator the color change is gold to pink. In cases with high levels of fluorine, it is best to add Boric acid.

The most common standard for this determination is Cystine available through the NIST. There are others that may be used on occasion.

The preceding is a brief description of our techniques used in sulfur determination. Due to the exclusive use of the flask combustion in the sulfur determination, we are not able to determine sulfur on air-sensitive samples.

Experience has shown that Phosphorus, Selenium, Iodine, or Copper do show some interference, yielding lower results.  We are unable to perform analysis if these elements are present due to the accuracy of the results.