Helium-4 and neutron activation analysis for phosphorus in aluminium—silicon alloys

An instrumental determination of phosphorus in aluminium-silicon alloys by activation with 20-MeV helium-4 particles can be based on the ³¹P(α , n)^34m Cl reaction. A mixture of aluminium powder and disodium hydrogenphosphate is used as a standard. For concentrations ranging from 1.7 to 25 μg g^-1, the experimental standard deviation ranges from 1 to 24% with an average of 8%. The method was compared with thermal neutron activation analysis based on the ³¹P(n, γ)³²P reaction. ³²P was chemically separated by precipitation as ammonium molybdophosphate. This technique yielded results with a standard deviation between 0.3 and 7.5% with an average of 2%. The agreement between the two methods was satisfactory. The results were also compared with photometry and atomic absorption spectrometry.