Abstract: A method and apparatus for determining the phosphorus content which can be volatilized in a solid carbon sample. The sample is heated in the presence of steam to produce a vaporous steam containing volatile phosphorus. Next, the vaporous stream is passed through a zinc oxide layer whereby the voliatle phosphorus is retained. A colored solution is formed upon adding to the zinc oxide layer a vanadate-molybdate reagent. Finnally, the intensity of the colored solution is determined by a spectrophotometer; and the phosphorus content is determined by comparison with a standard intensity graph.