Section 2: Principle of the Method

In this method, the detergent is dissolved in water and heated with ammonium persulphate and sulphuric acid to destroy a large part of the organic material and to hydrolyze the polyphosphates to orthophosphates. The solution is then diluted in a "Technicon Autoanalyzer" system, ammonium molybdate is added to form the heteropolymolybdophosphoric acid, and this complex is then reduced to molybdenum blue with stannous chloride. Because of the great dilution in the system and the high sensitivity of the stannous chloride-molybdenum, blue determination, it is possible to run the digested detergent solution directly without filtration or dialysis.