Instrumental analysis of phosphorus in organic material using high energy beta-counting after photoactivation (IPAA)

C, N, O, F and P can be analyzed by instrumental photon activation analysis (IPAA) including decay curve analysis. The interference of ³⁰P (T _1/2 = 149.9 s) by ¹⁵O (T _1/2 = 122.2 s) can be ruled out by direct positron measurement making use of the largely different maximum β⁺-energies of both nuclides (3.24 MeV and 1.73 MeV, respectively). Interference by carbon (¹¹C) can be avoided by sub-threshold activation with 17 MeV bremsstrahlung. The short half-life of ³⁰P allows a high productivity of the method. Reliability was demonstrated in the range of 0.2%–2% P (detection limit = 40 μg/g). Analysis of a certified reference material (BCR-CRM 063) yielded excellent agreement with the certified data.