Phosphorus Determination by Murphy-Riley Method

The Murphy-Riley colorimetric method has been widely used to measure the phosphorus content in natural waters as well as in foods. The method is applicable to most foods after dry ashing of a food sample. The Murphy-Riley method involves an oxidation-reduction reaction in which phosphorus is reacted to form a chromogen-mineral complex that can be measured with a spectrophotometer at a visible wavelength. In this laboratory exercise, the phosphorus content of an ashed milk sample is determined by the Murphy-Riley method, which involves preparation of a phosphorus standard curve.