Abstract: A new method is disclosed for determining sulfur levels in liquid or solid samples. The method is capable of accurate determination of sulfur content at sub-parts per million levels. The method and apparatus utilize high temperature oxidation of the samples to form sulfur oxides, absorption of the sulfur oxides on copper oxide as copper sulfate, thermal decomposition of the sulfate to convert sulfur present to sulfur dioxide which is evolved and coulometric titration to measure the quantity of evolved sulfur dioxide from which sulfur content of the sample can be calculated.