Non-destructive determination of nitrogen in malting barleys by instrumental photon activation analysis and its comparison with the Dumas method

Instrumental photon activation analysis (IPAA) was used to measure the nitrogen content of malting barleys used in brewing and breeding in the Czech Republic. The study compares the fast and non-destructive IPAA method with the classical Dumas method requiring combustion of the sample. The IPAA procedure for nitrogen assay is based on measuring the positron-electron annihilation line at 511keV from the photoactivation product N-13, which is interfered with by other positron emitting nuclides. Interference from O-15 can be eliminated by counting after a sufficient decay time. Interferences from Cl-34m and K-38 can be corrected via measuring their specific lines at 146.4 and 2167.7keV, respectively. The IPAA procedure has been verified by analysis of several biological reference materials and is suitable for nitrogen measurement in cereals and other plant materials with a detection limit down to 10(-2)wt%. Nitrogen contents in malting barleys ranged from 1.4 to 2.2wt% and were dependent on the cereal variety and growth conditions (fertilizer use and chemical protection). Copyright (c) 2018 The Institute of Brewing & Distilling