Authors:R. Zwicker, B. Zwicker, S. Laoharojanaphand, and A. Chatt
Neutron activation analysis (NAA) methods were employed for the determination of total arsenic, and water soluble As(III)
and As(V) compounds in freshwater fish/shellfish and plant samples from Southern Thailand. Total arsenic concentrations varied
from 0.05 to 425 mg kg−1. Water soluble arsenic species were separated by solvent extraction using ammonium pyrrolidinedithiocarbamate (APDC)/methylisobutylketone
(MIBK) followed by NAA. The water soluble As(III) and As(V) levels varied from 0.07 to 26.4 and 0.03 to 22.9 mg kg−1, respectively. The As(III) and As(V) detection limits were 0.007 for fish/shellfish, 0.005 for As(III) and 0.006 mg kg−1 for As(V) in plants. This separation method allows for the determination of water soluble As(III) and As(V) using commonly
available and inexpensive laboratory equipment and chemicals, which can be coupled to a variety of quantification techniques.
Authors:W. Menendez Sanchez, B. Zwicker, and A. Chatt
A combination of solid phase extraction, coprecipitation, and neutron activation techniques has been used to develop a speciation
analysis method based on green chemistry for the major arsenic species in drinking water. Arsenate as As(V), monomethylarsonic
acid (MMA), and dimethylarsinic acid (DMA) are separated and preconcentrated by strongly anion and cation exchange columns
in tandem while As(III) remains in the effluent. These species are then selectively eluted and As(III) coprecipitated with
bismuth sulphide. This simple method has been applied to the analysis of water reference materials with good results. The
detection limits are 0.9, 1.7, 1.6, 3.8 and 16 ng mL−1 for As(III), As(V), MMA, DMA and total arsenic, respectively, using a neutron flux of 2.5 × 1011 cm−2 s−1 at the Dalhousie University SLOWPOKE-2 reactor (DUSR) facility and anti-coincidence gamma-ray spectrometry.
Chemical separation methods in conjunction with instrumental neutron activation analysis (INAA) were developed for measuring
iodine levels in commercially available bovine milk with varying milk fat (MF) content. Samples of homogenized (3.25 % MF),
partly skimmed (2 % MF), partly skimmed (1 % MF), partly skimmed calcium enriched (1 % MF + Ca), and skim (<0.05 %) milk were
purchased from local supermarkets. Ion exchange chromatography, solvent extraction, and ammonium sulfate precipitation methods
were applied to the separation of the inorganic, lipidic and proteic fractions of iodine in milk. The levels of iodine were
measured by INAA in total reactor and epi-cadmium (EINAA) neutron flux in conjunction with conventional gamma-ray and Compton
suppression spectrometry (CSS). A pseudo-cyclic INAA method coupled with CSS (PC-INAA-CSS) was also explored as an instrumental
option to further lower the detection limit of iodine. The detection limits of 0.06, 0.06 and 0.02 μg mL−1 for iodine were obtained using INAA-CSS, EINAA-CSS, and PC-INAA-CSS methods, respectively. Although the PC-INAA-CSS method
provided the lowest detection limit, the INAA-CSS method was sufficient for the determination of total iodine in almost all
samples analyzed in this work. The total iodine concentrations (μg mL−1) were: 0.40 ± 0.01 (in 3.25 % MF), 0.40 ± 0.01 (2 % MF), 0.42 ± 0.01 (1 % MF), 0.42 ± 0.01 (<0.05 %), and 0.96 ± 0.01 (1 %
MF + Ca) milk samples. Iodine bound to various fractions of the milk samples analyzed, in percent of total iodine content,
ranged: (0.05–1.8), (1.9–4.8), (90–95) for the lipidic, proteic and anionic inorganic fractions respectively. Iodine recovery
in all cases was higher than 96 %.
An advanced neutron activation technique has been developed for the accurate analysis of elemental and isotopic fissile material required in nuclear safeguards, nuclear material standardization and other applications. It is based on reactor neutron flux spectrum differentiation by cadmium screening and multistandard calibration, including the solution of a second order equation system or of computerized calibration curve fitting, taking into account the thermal neutron flux depression. Some discrepancies at high enrichments have still to be eliminated in order to achieve the required measurement accuracy.
Authors:G. P. Westphal, H. Lemmel, F. Grass, P. P. De Regge, K. Burns, and A. Markowicz
Dubbed “Analyzer” because of its simplicity, a neutron activation analysis facility for short-lived isomeric transitions is based on a low-cost rabbit system and an adaptive digital filter which are controlled by a software performing irradiation control, loss-free gamma-spectrometry, spectra evaluation, nuclide identification and calculation of concentrations in a fully automatic flow of operations. Designed for TRIGA reactors and constructed from inexpensive plastic tubing and an aluminum in-core part, the rabbit system features samples of 5 ml and 10 ml with sample separation at 150 ms and 200 ms transport time or 25 ml samples without separation at a transport time of 300 ms. By automatically adapting shaping times to pulse intervals the preloaded digital filter gives best throughput at best resolution up to input counting rates of 106 cps. Loss-free counting enables quantitative correction of counting losses of up to 99%. As a test of system reproducibility in sample separation geometry, K, Cl, Mn, Mg, Ca, Sc, and V have been determined in various reference materials at excellent agreement with consensus values.
Authors:V. Karandashev, R. Kuznetsov, and S. Grazhulene
The extraction and extraction-chromatographic behavior of many elements in the tributylphosphate — HBr solution system has been studied. The investigation performed has made it possible to develop a simple technique for neutron activation determination of 22 impurity elements in high purity indium samples with detection limits from 0.1 ppm for Fe and Zr to 0.01 ppb for Na, Sc, Cu, As, La and W.
Authors:S. Khaled, M. Mouzai, A. Ararem, L. Hamidatou, and B. Zouranen
Traditional medicinal seeds prescribed for specific treatment purposes, were purchased from local markets and analyzed by
INAA. The samples were irradiated at Es-Salam research reactor, at a power of 5 MW for 6 h. The accuracy of the method was
established by analyzing reference materials. Twenty elements were measured, with good accuracy and reproducibility. The concentration
of elements determined, was found to vary depending on the seeds. The daily intake of essential and toxic elements was determined,
and compared with the recommended values. The probable cumulative intake of toxic elements is well below the tolerance limits.