Prompt gamma ray neutron activation analysis methodologies were standardized using a reflected neutron beam and Compton suppressed
γ-ray spectrometer to quantify boron from trace to major concentrations. Neutron self-shielding correction factors for higher
boron contents (0.2–10 mg) in samples were obtained from the sensitivity of chlorine by irradiating KCl with and without boron.
This method was validated by determining boron concentrations in six boron compounds and applied to three borosilicate glass
samples with boron contents in the range of 1–10 mg. Low concentrations of boron (10–58 mg kg−1) were also determined in two samples and five reference materials from NIST and IAEA.
The neutron spectra of one outer (#10) and two inner (#2 and #3) sites of the Dalhousie University SLOWPOKE-2 reactor (DUSR) have been calibrated for the k0-based neutron activation analysis (k0-NAA). The parameters determined include the cadmium ratio (RCd), epithermal neutron flux shape factor (), subcadmium-to-epithermal neutron flux ratio (f), thermal-to-fast neutron flux ratio (fF), modified spectral index r()(Tn/T0)1/2, Westcott gLu(Tn)-factor, and absolute neutron temperature (Tn). The a-values of -0.0098±0.0045 and -0.0425±0.0047 and -0.0422±0.0053 and f-values of 57.1±2.2 and 18.8±0.4 and 18.9±0.4 were obtained for the sites #10, #2 and #3, respectively. The modified spectral index (MSI), gLu(Tn)-factor, and Tn have been determined for the handling of non 1/v (n,) reactions. The accuracy of the method was evaluated by analyzing reference materials.
Epithermal instrumental neutron activation analysis (EINAA) technique in conjunction with anti-coincidence gamma-ray spectrometry
(AC) has been applied for the determination of ppm to ppb levels of iodine in biological materials containing high levels
of Al, Br, Cl, K, Mn, and Na. Both conventional EINAA-AC and pseudo-cyclic EINAA-AC (PC-EINAA-AC) methods using a combination
of Cd and B filters have been developed using Dalhousie University SLOWPOKE-2 reactor (DUSR) facility. The expanded uncertainties
(EU), at about 95% confidence level, for iodine in biological materials by EINAA-AC varied between 6 and 10%. The advantages
of the non-destructive PC-EINAA-AC method has been successfully demonstrated by analyzing the NIST Pine Needles (SRM 1575)
containing a low amount of iodine in presence of high quantities of Mn and other interfering elements where an iodine content
of 92.8 μg kg−1 with an EU of 6.1 μg kg−1 and a detection limit of 40 μg kg−1 has been obtained at the end of fourth cycle.
Nickel contents in different finished product alloys were determined using a k0-based internal monostandard instrumental neutron activation analysis (IM-INAA) method. Five stainless steels (SS) and three
high nickel alloys were analyzed by IM-INAA. BCS CRMs 225/1 (low alloy steel) and 466 (austenitic SS) and NIST SRM 247 (high
Ni alloy) were analyzed to evaluate the accuracy of the method. The results of CRMs and SS were found to be in good agreement
with certified or specified values. The Ni contents in the high nickel alloys were also determined by relative method of NAA
for verification. Nickel contents in BCS CRM 466 and SS 316M were determined by UV–Visible spectrophotometry and the values
were found to be in good agreement with IM-INAA results.
Ground water samples obtained from West Bengal, India were analyzed for total arsenic and its inorganic species contents by
instrumental neutron activation analysis (INAA). Two anion exchange separation methods using Dowex 1X8 in chloride and acetate
forms were standardized for the speciation of As(III) and As(V) using radiotracers. The method by Dowex 1X8 in the acetate
form was validated using synthetic mixtures of As(III) and As(V), and applied to water samples; the species concentrations
were determined by INAA. The accuracy of the INAA method was evaluated by analyzing the NRCC CRM DORM-2 for total arsenic.
Uranium and thorium mixed oxides are being prepared using natural U and Th for studies on fuels for Advanced Heavy Water Reactors,
wherein composition of U and Th is specific and requires strict control in terms their contents and homogeneity. Chemical
quality control necessitates accurate and precise compositional characterization of the fuel material by a suitable analytical
method. Among various analytical methods for U and Th, instrumental neutron activation analysis (INAA) is one of the best
methods for their simultaneous determination without chemical dissolution and separation. INAA methods using reactor neutrons
namely thermal NAA and epithermal NAA were standardized for the determination of U and Th in their mixed oxides. Standards,
synthetic samples and U–Th mixed oxide samples, prepared in cellulose matrix, were irradiated at pneumatic carrier facility
of Dhruva reactor as well as at self serve facility of CIRUS reactor under cadmium cover (0.5 mm). Radioactive assay was carried
out using a 40% relative efficiency HPGe detector. Both activation and daughter products of 238U (239U and 239Np) and 232Th (233Th and 233Pa) were used for their concentration determination. The method was validated by analyzing synthetic samples of 6–48%U–Th
mixed oxides. The standardized method was used for the concentration determination of U and Th in 4–30%U–Th mixed oxide samples.
Results of U and Th concentrations including associated uncertainties obtained from the INAA methods are presented in this
Authors:R. Maharia, R. Dutta, R. Acharya, and A. Reddy
Three commonly used medicinal plants, e.g., Adhatoda vasica, Cassia fistula, and Withania somnifera grown in two contrasting environmental conditions, namely from copper mining site and from control site corresponding to
soil not contaminated with Cu, to understand correlations between high Cu bioaccumulation in medicinal plants on their antioxidant
activities. Concentrations of some essential metals, e.g., Cr, Mn, Fe, Cu, Zn, and Se in the leaves of these plants were measured
by instrumental neutron activation analysis. The Cu levels in the samples from mining site were in the range of 32.6 to 57.2 mg/kg,
which were 5–7 folds higher than the control samples, while Cr levels were about 2-folds higher in the mining site. Speciation
studies of Cr revealed negligible content of toxic hexavalent Cr. Antioxidant assay of these plants from both the sampling
sites, measured as total phenolic content, total flavonoid content, 2,2′-diphenyl-1-picrylhydrazyl, free radical scavenging
ability, and chelating ability with ferrous ions exhibited maximum activity for A. vasica, while that of W. somnifera was minimum. However, the variations in the antioxidant activities for each medicinal plant species from mining site and
control site did not reveal significant differences.