On the Estimation of Organic Phosphorus

In attempting to use the methods of Bloor and Bell and Doisy for estimating liopoid phosphorus, difficulty was experienced in securing uniform results. A study of these methods was therefore made using pure inorganic phosphate solutions. Complete recovery was rarely possible and the apparent losses were quite variable. After excluding other steps in the processes as possible causes of error, attention was given to the ashing process, modifications of the Neumann ashing process being used. In this method, which had given satisfaction for the macro estimation of phosphorus for a long time, two possible sources of error were discovered.Although when heated alone, phosphoric acid does not volatilize until a temperature of about 260° C. is reached, when it is heated with sulphuric acid at 180°-200° C. it volatilizes slowly in the vapors of sulphuric acid—a fact which the writer subsequently found had been demonstrated by Hillebrand and Lundell. This source of loss was found to occur both in the Bloor and Bell ...