Filters
Results 1 - 1 of 1
Results 1 - 1 of 1.
Search took: 0.017 seconds
AbstractAbstract
[en] Iodine is an element of interest in nutritional research. Its lower limit of safe and adequate daily dietary intake for adults varies between 150 and 200 micrograms per day. In the present study, an epithermal instrumental neutron activation analysis (EINAA) method in conjunction with anti-coincidence counting has been developed for the determination of ppb levels of iodine in individual food items. Typically 200-300 mg of a sample are irradiated for 10 or 20 minutes at the Dalhousie University SLOWPOKE-2 reactor in an epithermal flux of 1x1011 n cm-2 s-1, followed by 1 min decay and then counting for 30 min. The 443-keV gamma-ray of 128I is used for measuring iodine content by anti-coincidence counting. The anti-coincidence spectrometer consists of a 25% HPGe detector surrounded by a 10''x10'' NaI(TI) annulus and a 3''x3'' NaI(TI) plug. This system has a peak-to-Compton ratio of about 650 to 1 for the 661.6-keV photopeak of 137Cs. The Compton background resulting from the scattering of many gamma-rays of energies higher than 443 keV can be reduced by a factor of about 4 using anti-coincidence counting compared to conventional counting. The detection limit for iodine can be improved by a factor of 2 to 5 depending on the sample matrix, dead time, position of the annulus and counting geometry among several other factors.The lowest detection limit of 5 ppb can be achieved for low-salt foods. This limit is comparable to that obtained by a preconcentration NAA (PNAA) method. However, a detection limit of 20 ppb is more realistic for samples containing high amounts of Na, Cl and Al. The results obtained for many reference materials are in good agreement with the certified values and those reported by the PNAA method. Details of the methods and results will be reported
Primary Subject
Source
Hardy, C.J. (ed.); Australian Nuclear Association Inc., Sutherland, NSW (Australia); 332 p; Oct 1997; p. 284-289; 2ICI: Second international conference on isotopes; Sydney, NSW (Australia); 12-16 Oct 1997; 6 refs., 2 tabs.
Record Type
Miscellaneous
Literature Type
Conference; Numerical Data
Report Number
Country of publication
ACTIVATION ANALYSIS, BARYONS, BETA DECAY RADIOISOTOPES, BETA-MINUS DECAY RADIOISOTOPES, BETA-PLUS DECAY RADIOISOTOPES, CHEMICAL ANALYSIS, COUNTING TECHNIQUES, DATA, ELECTRON CAPTURE RADIOISOTOPES, ELEMENTARY PARTICLES, ELEMENTS, ENERGY RANGE, EVALUATION, FERMIONS, HADRONS, HALOGENS, INFORMATION, INTERMEDIATE MASS NUCLEI, IODINE ISOTOPES, ISOTOPES, KEV RANGE, MATERIALS, MINUTES LIVING RADIOISOTOPES, NEUTRONS, NONDESTRUCTIVE ANALYSIS, NONMETALS, NUCLEI, NUCLEONS, NUMERICAL DATA, ODD-ODD NUCLEI, RADIOISOTOPES, SPECTROSCOPY
Reference NumberReference Number
Related RecordRelated Record
INIS VolumeINIS Volume
INIS IssueINIS Issue