Determination of elemental sulfur in phosphorous pentasulfide by temperature modulated differential scanning calorimetry

Phosphorous pentasulfide is an important starting material for a number of commercial chemicals. Examples include lubricant additives (Spikes, Trib Lett 17:469?C489, 2004), agricultural insecticides (Kirk-Othmer, Enycl Chem Technol 14:549?C552, 1995), and mining ore flotation agents. Phosphorous pentasulfide is a mixture of several components, one of which is free elemental sulfur, present at levels of approximately 50?ppm to 20,000?ppm (2?%). The amount of free sulfur present in the phosphorous pentasulfide can impact manufacturing, such as zinc dithiosulfate processing. Therefore, an accurate and fast analytical method to measure elemental sulfur in phosphorous pentasulfide would be of value compared to what is available now.