GammaLab: a suite of programs for k 0 -NAA and gamma-ray spectrum analysis

Characterization of toothpastes for fluorine and other elements by INAA and ICP-OES

Fluoride toothpastes have made a significant contribution towards oral hygiene. This study proposes instrumental neutron activation analysis (INAA) as a suitable technique for determining fluorine in toothpastes. The method involved a 10 s irradiation, followed by 10–20 s decay, and counting for 10 s, using a pneumatic system and high purity germanium detector. All irradiations were performed at miniature neutron source reactor with thermal neutron flux 1 × 1012 cm−2 s−1. Since Na was present in all toothpastes, the quantification of fluorine required correction for 23Na(n,α)20F threshold reaction. Fluorine determination was validated by analysing the samples by ion chromatography. All toothpastes were also analysed for other elements by k 0-INAA and ICP-OES. Both techniques quantified 28 elements including Al, As, Ba, Ca, Ce, Cl, Co, Cr, Cu, F, Fe, Hf, K, La, Mg, Mn, Na, P, S, Sb, Sc, Si, Sm, Sn, Sr, Ta, Ti and Zn. This study, categorized toothpastes in five groups based on concentrations of Ca, P and Ti.

Soil mineral analysis and environmental radioactivity in Ghizer, Eastern Hindukush, Pakistan

Distribution of natural and anthropogenic radionuclides (226Ra, 232Th, 137Cs and 40K) was determined in 32 samples from Ghizer, an Eastern Hindukush district at an altitude of 2286 m in Pakistan using high resolution gamma-ray spectrometry. Mineralogical analysis by X-ray diffractometry identified quartz, calcite, albite and anorthite as major phases whereas actinolite, chlorite serpentine and kaolinite as minor phases. The activity concentrations for 226Ra, 232Th, 137Cs and 40K varied from 25.2 ± 1.7 to 145.3 ± 10.1 Bq kg−1, 24.9 ± 1.1 to 197 ± 9 Bq kg−1, 2.03 ± 0.21 to 16.7 ± 1.1 and 252 ± 6 to 1433 ± 35 Bq kg−1, respectively. The samples yielded average radium equivalent activity as 178.4 ± 23.3 Bq kg−1. The majority of the samples revealed external hazard index and representative level index less than one. The average air absorbed dose rate was 91.2 ± 13.6 nGy h−1 corresponding to the annual effective dose rate 111.8 ± 17.4 μSv y−1. These values were higher than the world averages for air absorbed dose rate and outdoor annual effective dose rate. Principal component analysis was applied to obtain distribution pattern within the samples and among the radionuclides.

CHARACTERIZATION OF SAND SAMPLES FROM KARACHI BEACHES USING GAMMA SPECTROMETRY AND XRD

Chemical phase and distribution of natural radionuclides (226Ra, 232Th and 40K) were determined for sand samples collected from ten different beaches of Karachi. All samples, except one, were identified with major and minor phases as SiO2 and CaCO3, respectively. The average activity concentrations were 24.9, 25.0 and 239 Bq kg-1 for 226Ra, 232Th and 40K, respectively. Including all samples, the average radium equivalent activity was 79.1 Bq kg-1. The external and internal radiation hazard indices and representative level index were all found below unity. The average air absorbed dose rate at 1 m above the sand due to the natural radionuclides was 18.3 nGy h-1, which was less than the world average for soil. The corresponding annual effective dose rate was 22.4 μSv y-1. It was found that Raeq had positive significant correlation with the amount of quartz present at the beaches.

Elemental Characterization of Medicinal Plants and Soils from Hazarganji Chiltan National Park and Nearby Unprotected Areas of Balochistan, Pakistan

The aim of this work was to evaluate the variability in elemental composition of seven medicinal plants and their respective soils belonging to protected and nearby unprotected sites of the Hazarganji Chiltan National Park. The medical plants under study were Achillea wilhelmsii C. Koch, Peganum harmala Linn, Sophora mollis (Royle) Baker, Perovskia atriplicifolia Benth, Seriphidium quettense (Podlech.) Ling, Hertia intermedia (Bioss) O. Ktze, and Nepeta praetervisa Rech. F. Macro (C, H, N, S, K, Ca), micro (Cl, Cu, Fe, Mn, and Zn), beneficial (Al, Co, Na), others (As, Br, Cr, Cs, Hf, Pb, Rb, Sb, Sr, Sn, V and Th) and rare earth elements (Ce, Eu, La, Lu, Nd Sc, Sm, Tb and Yb) were characterized by means of standard organic elemental and instrumental neutron activation methodologies and by flame atomic absorption spectroscopy. Results showed that, among macro nutrients, carbon concentration was the highest element in both plant and soil samples followed by H and K. Elements such as Cl, Na and Fe were detected in considerably good amounts; all the other elements were found in trace quantities. Principal component analysis (PCA) was applied to identify spatial variation in elemental composition of medicinal plants, in which 80-90% of the total variance in whole set of data was found. In particular, the findings highlighted the presence of essential and beneficial elements such as C, H, N, K, Ca, Fe, Mn and Na, in samples from protected sites, while potentially dangerous elements such as Al, As, Br and Cr were detected in samples from unprotected sites. These results emphasized on the need for rational exploitation of valuable medicinal plants and supporting protected areas as an excellent source of biodiversity conservation.

Development of radiochemistry in Pakistan – 1960 to 2010

With the inception of Pakistan Atomic Energy Commission (PAEC) in 1956, peaceful uses of atomic energy commenced for the benefit of scientific community as well as masses of Pakistan. Radiochemistry played a vital role right from the beginning. The research and development in this field accelerated soon after the criticality of the first research reactor named as Pakistan Research Reactor (PARR- 1) at the Pakistan Institute of Nuclear Science and Technology (PINSTECH), Islamabad. The first radioisotope produced at PARR-1 for application in nuclear medicine was 131I. Later on, many other radioisotopes were prepared and radiopharmaceuticals were synthesised for their use in industry and hospitals. Besides providing pure radioactive tracers for nuclear medicine, radiochemistry also enhanced the detection limit of impurities at all stages of nuclear fuel cycle for power generation. In 1983, research in the field of nuclear data measurement began. The main aim was to identify suitable conditions for the production of radionuclides for cancer diagnostics, treatment and therapy. With the establishment of a second research reactor (PARR-2) at PINSTECH, research in neutron activation analysis, radioisotope production and separation studies gained more momentum and many research articles were published. Solvent extraction, adsorption and ion-exchange were the main routes of separation in those studies. Separation of heavy metals and treatment of waste generated in a nuclear power plant are other important aspects related to environmental restoration and nuclear waste management, where radiochemistry is required. In future, work in radiochemistry will be continued on similar lines to develop novel radiopharmaceuticals, identify indigenous schemes for nuclear waste management and work out intelligent procedures for material characterization for benefit to mankind, especially the people of Pakistan.

Determination of the risk associated with the natural and anthropogenic radionuclides from the soil of Skardu in Central Karakoram

The radioactivity levels were determined in 39 soil samples from six towns of Skardu using gamma-ray spectrometry. The samples were collected at an average altitude of 2293 m above sea level in Central Karakoram. The activity concentration data were analysed by principal component analysis for outlier detection and data structure elucidation and for frequency distributions. The median activity concentrations of (226)Ra, (232)Th, (40)K and (137)Cs were found to be 49.8 ± 12.6, 80.9 ± 18.7, 977 ± 91 and 4.37 ± 4.08 Bq kg(-1), respectively. An uncertainty analysis showed that the main contribution to uncertainty budget was from the counting statistics and uncertainty in the reference activity of standard. The activity concentration data showed a positive significant correlation between (226)Ra and (232)Th. Three hazard indices named the radium equivalent activity, external hazard index and internal hazard index were calculated. In the total activity concentration, (40)K accounted for the most (87.5 %), whilst in the radium equivalent activity, (232)Th contributed the most (48.5 %). In the Skardu samples, the air-absorbed dose rate was found to be 112 ± 17 nGy h(-1), annual effective dose rate from terrestrial to be 243 ± 38 μSv y(-1), effective dose rate due to the deposition of (137)Cs on soil to be 1.1 ± 2.4 μSv y(-1) and dose rate from the cosmic radiations to be 1371 ± 107 μSv y(-1). The ratio of mass fractions of Th/U was 4.8 ± 0.6.The results were compared with the similar measurements made in other parts of the world. A comparison with the other cities of Pakistan revealed that the soil in Skardu presented the highest external exposure rate.

Neutron activation analysis and atomic absorption spectrophotometry for the analysis of fresh, pasteurised and powder milk

This study shows the application of semi-absolute k 0 instrumental neutron activation analysis (k 0-INAA), epithermal neutron activation analysis (ENAA) and atomic absorption spectrophotometry (AAS) for the determination of 21 elements (Br, Ca, Cl, Co, Cr, Cs, Cu, Fe, Hf, I, K, Mg, Mn, Na, Ni, P, Pb, Rb, Sc Sr, and Zn) in different types of milk samples. The ENAA was required for the determination of iodine, AAS for Cu, Ni and Pb and the rest of the elements were measured by k 0-INAA. Thirteen elements (Br, Ca, Cl, Cs, Cu, Fe, K, Mg, Na, P, Rb, Sr and Zn) were identified in all milk samples. Ni was detected in eleven and Pb in two samples. Concentrations of most of the elements were within the ranges of the world reported data. The data was further explored by principal component analysis to find relationships between samples and elements.

Comparative performance of semi-absolute k 0-instrumental neutron activation analysis and Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) for compositional decoding of aluminum base alloys

Samples of certified aluminum base alloys were analyzed by semi-absolute, standardless k 0-instrumental neutron activation analysis (k 0-INAA) for compositional decoding. Irradiations were performed at two research reactors located at Pakistan Institute of Nuclear Science and Technology having nominal thermal neutron fluxes of 1013 and 1012 cm−2 s−1. The experimentally optimized parameters for NAA suggest a maximum of three sets of irradiations for the quantification of 8 major and minor elements. Moreover, the same conditions provided quantitative results for 10 other elements as impurities, which were not reported by the supplier of the reference material. The same alloys were analyzed by inductively coupled plasma optical emission spectrometry (ICP-OES) where all impurity elements, quantified by k 0-INAA, were below the detection limits. A comparison of % relative deviation of the results obtained by k 0-INAA and ICP-OES revealed that the former has better accuracy than ICP-OES, but k 0-INAA has poor limits of detection for Mg, Si and Ti in aluminum base alloy.

Morus nigraplant leaves as biomonitor for elemental air pollution monitoring

The present paper deals with the determination of 36 elements in 120 leaf samples ofMorus nigraplant to assess their potential as biomonitor for elemental air pollution monitoring. The elemental quantification was made by employing Instrumental Neutron Activation Analysis (INAA) and Atomic Absorption Spectrometric (AAS) techniques. The leaf samples were collected in spring, summer and winter seasons from various sites in Islamabad with different types of anthropogenic activities as well as from a reference site with minimum of such activities. Twenty four soil samples from the respective sites were also analyzed. The reliability of the adopted procedures was established by analyzing the certified reference materials,i.e., citrus leaves-1572 and soil-7, from NIST and IAEA, respectively, under identical experimental conditions and comparing the results obtained with the certified values which are in quite good agreement with each other. The enrichment values and Pollution Load Index (PLI) of the determined elements were computed and discussed accordingly. The elemental translocation from soil to roots, stem and leaves has also been studied by analyzing these parts of the same plant. The results indicated that the leaves ofMorus nigraplant have promising potential to monitor the extent of air pollution in the vicinity of industrial as well as in high traffic areas.

Determination of the activation constants for miniature neutron source reactor (MNSR) by linear least squares regression

This paper presents a detailed description of the determination of experimental activation constants for 22 elements for miniature neutron source reactor (MNSR). The activation constants have been measured for the most intense γ-rays of the radionuclides commonly observed in neutron activation analysis. The experimental values have been compared with those based on mathematical expression and calculated by using f and α of the irradiation channel and k 0 and Q 0 factors from published literature. A comparison of the expression-based and experimentally determined activation constants shows a good agreement, except for some cases where difference is about 10% of the expression-based values. The activation constants were validated by analyzing synthetic multielement standards (SMELS-I and -II); the results revealed all elements within ±3 Z-score.