Application of k 0-based internal monostandard NAA for large sample analysis of clay pottery: as a part of inter comparison exercise

As a part of inter comparison exercise of an IAEA Coordinated Research Project on large sample neutron activation analysis, a large size and non standard geometry size pottery replica (obtained from Peru) was analyzed by k ₀-based internal monostandard neutron activation analysis (IM-NAA). Two large size sub samples (0.40 and 0.25 kg) were irradiated at graphite reflector position of AHWR Critical Facility in BARC, Trombay, Mumbai, India. Small samples (100–200 mg) were also analyzed by IM-NAA for comparison purpose. Radioactive assay was carried out using a 40 % relative efficiency HPGe detector. To examine homogeneity of the sample, counting was also carried out using X–Z rotary scanning unit. In situ relative detection efficiency was evaluated using gamma rays of the activation products in the irradiated sample in the energy range of 122–2,754 keV. Elemental concentration ratios with respect to Na of small size (100 mg mass) as well as large size (15 and 400 g) samples were used to check the homogeneity of the samples. Concentration ratios of 18 elements such as K, Sc, Cr, Mn, Fe, Co, Zn, As, Rb, Cs, La, Ce, Sm, Eu, Yb, Lu, Hf and Th with respect to Na (internal mono standard) were calculated using IM-NAA. Absolute concentrations were arrived at for both large and small samples using Na concentration, obtained from relative method of NAA. The percentage combined uncertainties at ±1 s confidence limit on the determined values were in the range of 3–9 %. Two IAEA reference materials SL-1 and SL-3 were analyzed by IM-NAA to evaluate accuracy of the method.     

Analysis of large and non-standard geometry samples of ancient potteries by internal monostandard neutron activation analysis using in situ detection efficiency

The k ₀-based internal monostandard neutron activation analysis (IM-NAA) method was used for the analysis of 30 large and non-standard geometry ancient pottery samples obtained from Buddhist sites of Andhra Pradesh, India. One freshly finished pottery and a sun-drenched pottery were also analyzed for comparison. Samples were irradiated in thermal column facility of Apsara reactor and also in graphite reflector position of critical facility of Bhabha Atomic Research Centre. Radioactive assay was carried out using a 40% relative efficiency HPGe detector coupled to MCA. Concentration ratios of 15 elements with respect to Sc were determined. The La/Ce values as well as statistical cluster analysis utilizing concentration ratios of elements were used for grouping/provenance of the potteries.     

A standardless approach of INAA for grouping study of ancient potteries

The k ₀ based internal monostandard neutron activation analysis was used to analyze 41 ancient pottery samples from three major locations of Andhra Pradesh state, India, belonging to two different age groups namely Megalithic and Buddhist periods. Samples were irradiated with neutron flux obtained from CIRUS reactor and radioactive assay was carried out using a 40% relative efficiency HPGe detector coupled to 8?k MCA. Concentration ratios of 21 elements were calculated with respect to internal monostandard Sc. Absolute concentrations for six (three each from both Megalithic and Buddhist periods) representative samples along with a modern pottery were obtained for comparison. Elemental concentration ratios with respect to Sc were used for grouping of these archaeological samples. Preliminary grouping of these artifacts was done using La/Ce values, and the grouping was confirmed by statistical cluster analysis using eleven selected trace elements. The IAEA RM SL-3 sample was analysed for validation of the method, where in both concentration ratios and absolute concentrations were calculated.     

Large sample neutron activation analysis of dross for gold and silver

Large sample neutron activation analysis of dross from India Government Mint, Mumbai was carried out for quantification of gold (Au) and silver (Ag) using graphite reflector position of Advanced Heavy Water Reactor critical facility at Bhabha Atomic Research Centre, Mumbai. The k ₀-based internal monostandard NAA was used to calculate concentration ratios of Au and Ag with respect to sodium (Na), which was used as an internal monostandard. The concentration ratio values of Au to Na of varying mass of dross showed that mass ≥2 g was the representative sample size for analysis. Concentrations of gold and silver were found to be in the range of 200–400 and 1200–1700 mg kg^?1, respectively in three different samples.     

Evaluation of soil to tea plant elemental correlation using instrumental neutron activation analysis

Instrumental neutron activation analysis using relative and k ₀-based internal monostandard methods were employed for determination of concentrations of 12 elements in soil and tea plants collected from three different tea producing regions in India namely Assam, Darjeeling and Kangra. A total of 17 tea leaf samples along with corresponding soil samples were analyzed for elemental content. The obtained concentration data was used for the soil–plant elemental correlation studies. Positive correlation was observed between elemental concentrations of tea plants and the associated soil with Pearson correlation coefficient values in the range 0.6–0.9 for ten elements. Variations in transfer factor values were also observed according to the geo-chemical variation.     

Trace element determination in high-purity aluminum clad samples by k 0-based internal monostandard instrumental neutron activation analysis

The k₀-based internal monostandard instrumental neutron activation analysis (IM-INAA) method was applied for quantification of trace impurities in seven high purity aluminum samples used as fuel cladding in a research reactor. Samples along with BCS CRM 182 (Si–Al alloy) were irradiated in high flux reactor neutrons for 10–15 h. In situ detection efficiency, needed in concentration calculation ratio by IM-INAA, was obtained using gamma rays of activation products produced in the samples. Elemental concentration ratios obtained with respect to Fe (used as internal monostandard) were converted to absolute concentrations by determining concentration of Fe by relative method of NAA. Concentrations of ten trace elements (Sc, Cr, Co, Zn, Ga, La, Ce, Sm, W and Hf) including major element Fe were determined in this work. The method used is non-destructive in nature and does not need multielement standards. Results of IM-INAA were compared with those obtained by relative method of INAA and inductively coupled plasma atomic emission spectrometry (ICP-AES). Details of methodologies and results obtained by all methods are discussed and compared in the paper.     

Application of k 0-based internal mono-standard PGNAA for compositional characterization of cement samples

The k ₀-based internal mono-standard prompt gamma-ray neutron activation analysis (IM-PGNAA) method was used for compositional analysis of a cement standard provided by the International Atomic Energy Agency as a part of inter-laboratory comparison exercise. The PGNAA was also applied to a local cement sample for comparison purpose. The concentration ratios of elements with respect Ca were determined using the internal mono-standard method. The concentration ratios were then converted to the absolute concentrations by determining concentration of Ca in the cement using relative method. Concentrations of 11 elements were determined in both sample and standard of cement. The results of cement standard are found to be in good agreement with the certified values. The uncertainties on the elemental concentrations were in the range of 5–10 %.     

The preparation and homogeneity study of synthetic multi-element standards (SMELS) for QC/QA of k0-NAA

Three new synthetic multi-element standards (SMELS) were developed for testing the performance of the k ₀-standardization neutron activation analysis (k ₀-NAA) method when implemented in a laboratory. SMELS consist of a phenol-formaldehyde polymer matrix spiked with different groups of elements according to the half-lives of the formed radionuclides. They are classified as Type I for short-, Type II for medium- and Type III for long-lived radionuclides. This article presents the preparation of SMELS including different aspects such as choice of the matrix and spiking elements, chemical compounds, target concentrations, purity of the matrix and spiking procedure and the homogeneity study for all the spiked elements in order to demonstrate the quality of the produced materials.     

Calibration of the B54X channel and implementation of k 0-NAA at the RA3-reactor,Ezeiza, Argentina

The B54X position of the 8 MW RA3 research reactor at the Ezeiza Atomic Centre of the Argentine National Atomic Energy Commission is currently being used for NAA irradiations. The facility with a nominal average fluence of 5 × 10¹³ cm^?2 s^?1 is dedicated to long irradiations of up to 5 h. Samples are being measured after a decay of typically 7 and 30 days. With the aim of implementing the k ₀-NAA method at the Nuclear Analytical Techniques Laboratory of the Centre, the reactor parameters α and f were estimated applying multi monitor methods using the Kayzero for Windows software. After a careful recalibration of the HPGe detector, SMELS III, NIST SRM 1633b and several other matrix RM’s were analyzed using the k ₀ standardization in order to verify the proper implementation of the k ₀-NAA approach. The found accuracy and associated uncertainties are discussed. In general, good agreement was obtained between results of this work and the reference values of the individual reference materials, thus proving successful first implementation of the above method and trueness of the results achieved. The obtained detection limits for several elements were evaluated.     

Determination of Nateglinide in Human Plasma by LC-ESI-MS and Its Application to Bioequivalence Study

To evaluate the bioequivalence of nateglinide, a rapid and specific liquid chromatographic-electrospray ionization mass spectrometric method was developed and validated to determine nateglinide for human plasma samples. The analyte was detected using electrospray positive ionization mass spectrometry in the selected ion monitoring mode. Tinidazole was used as the internal standard. A good linear relationship obtained in the concentration ranged from 0.05 to 16 μg mL^?1 (r ² = 0.9993). Lower limit of quantification was 0.05 μg mL^?1 using 100 μL of plasma sample. Intra- and inter-day relative standard deviations were 2.1–7.5 and 4.7–8.9%, respectively. Among the pharmacokinetic data obtained, T _max was 2.09 ± 1.06 h for reference formulation and 2.40 ± 0.97 h for test formulation. C _max was 4.17 ± 1.31 μg mL^?1 for reference formulation and 4.37 ± 1.53 μg mL^?1 for test formulation. The half-life (t _½) was 1.93 ± 0.44 h for reference formulation and 1.92 ± 0.29 h for test formulation. AUC_0–10h was 13.67 ± 4.36 μg h mL^?1 for reference formulation and 13.21 ± 4.09 μg h mL^?1 for test formulation. This method was successfully applied to the pharmacokinetic study in human plasma samples.     

HPLC Analysis and Pharmacokinetic Study of Paeoniflorin after Intravenous Administration of a New Frozen Dry Powder Formulation in Rats

A simple and specific high performance liquid chromatographic (HPLC) method with UV detection using picroside II as the internal standard was developed and validated to determine the concentration of paeoniflorin in rat plasma and study its pharmacokinetics after an single intravenous administration of 40 mg kg^?1 paeoniflorin to Wistar rats. The analytes of interest were extracted from rat plasma samples by ethyl acetate after acidification with 0.05 mol L^?1 NaH₂PO₄ solution (pH 5.0). Chromatographic separation was achieved on an Agilent XDB C₁₈ column (250 × 4.6 mm I.D., 5 μm) with a Shim-pack GVP-ODS C₁₈ guard column (10 × 4.6 mm I.D., 5 μm) using a mobile phase consisting of acetonitrile–water–acetic acid (18:82:0.4, v/v/v) at a flow rate of 1.0 mL min^?1. The UV detection was performed at a wavelength of 230 nm. The linear calibration curves were obtained in the concentration range of 0.05–200.0 μg mL^?1 in rat plasma with the lower limit of quantification (LLOQ) of 0.05 μg mL^?1. The intra- and inter-day precisions in terms of % relative standard deviation (RSD) were lower than 5.7 and 8.2% in rat plasma, respectively. The accuracy in terms of % relative error (RE) ranged from ?1.9 to 2.6% in rat plasma. The extraction recoveries of paeoniflorin and picroside II were calculated to be 69.7 and 56.9%, respectively. This validated method was successfully applied to the pharmacokinetic study of a new paeoniflorin frozen dry power formulation. After single intravenous administration, the main pharmacokinetic parameters t _1/2, AUC_0-∞, CL_TOT, V _Z, MRT_0-∞ and V _ss were 0.739 ± 0.232 h, 43.75 ± 6.90 μg h mL^?1, 15.50 ± 2.46 L kg^?1 h^?1, 1.003 ± 0.401 L kg^?1, 0.480 ± 0.055 h and 0.444 ± 0.060 L kg^?1, respectively.     

LC Determination of a Novel Synthetic Thiazolidinedione (BP-1107) in Rat Plasma and Its Application to a Pharmacokinetic Study

A simple, rapid, sensitive and reliable liquid chromatographic method for the quantification of BP-1107 in rat plasma has been established. Plasma samples were prepared by extraction with tert-butyl methyl ether, and troglitazone was used as an internal standard. The analytical separation was performed on a C₁₈ column using acetonitrile–0.3% phosphoric acid in water (pH 4.00 adjusted with triethylamine) (75:25, v/v) as a mobile phase. A detailed validation of the method was performed as per USFDA guidelines. For BP-1107 at the concentrations of 2.42, 16.11 and 32.22 μg mL^?1 in rat plasma, the extraction recoveries were 114.14 ± 9.75, 95.37 ± 12.06 and 90.00 ± 6.46%, respectively. The mean recovery for internal standard was 91.96 ± 2.51%. The lower limit of quantitation of BP-1107 was 16 ng. The linear quantification range of the method was 0.81–53.70 μg mL^?1 in rat plasma with a correlation coefficient greater than 0.999. The intra-day and inter-day accuracy for BP-1107 at 2.42, 16.11 and 32.22 μg mL^?1 levels in rat plasma fell between 97.10–110.02 and 97.52–108.04%. The intra-day and inter-day precision were in the ranges of 1.91–5.63 and 4.43–6.28%, respectively. The method was successfully applied to a pharmacokinetic study of BP-1107 in rats after an intravenous administration.     

Optimization of operating parameters and rate of uranium bioleaching from a low-grade ore

In this study the bioleaching of a low-grade uranium ore containing 480 ppm uranium has been reported. The studies involved extraction of uranium using Acidithiobacillus ferrooxidans derived from the uranium mine samples. The maximum specific growth rate (µ ^max) and doubling time (t _d) were obtained 0.08 h^?1 and 8.66 h, respectively. Parameters such as Fe²⁺ concentration, particle size, temperature and pH were optimized. The effect of pulp density (PD) was also studied. Maximum uranium bio-dissolution of 100 ± 5 % was achieved under the conditions of pH 2.0, 5 % PD and 35 °C in 48 h with the particles of d ₈₀ = 100 μm. The optimum concentration of supplementary Fe²⁺ was dependent to the PD. This value was 0 and 10 g of FeSO₄·7H₂O/l at the PD of 5 and 15 %, respectively. The effects of time, pH and PD on the bioleaching process were studied using central composite design. New rate equation was improved for the uranium leaching rate. The rate of leaching is controlled with the concentrations of ferric and ferrous ions in solution. This study shows that uranium bioleaching may be an important process for the Saghand U mine at Yazd (Iran).     

LC Determination and Bioequivalence Study of Pantoprazole in Human Plasma

A selective and sensitive liquid chromatography (LC) method with rapid sample processing was developed for determination of pantoprazole in human plasma using omeprazole as internal standard (IS). The plasma sample (100 μL) was deproteined by precipitation with methanol. The supernatant was directly determined by LC using a Diamonsil C₁₈ ODS column and solution of 10 mM Na₂HPO₄ buffer (containing 0.01% H₃PO₄) and acetonitrile (68:32, v/v, pH = 6.8) as mobile phase with UV detector set at 288 nm. The retention time of IS and pantoprazole were 4.9 ± 0.2 and 5.6 ± 0.2 min, respectively. The method was validated with a linear range of 0.03–5.0 μg mL^?1 and the lowest limit of quantification was 0.03 μg mL^?1 for pantoprazole (r = 0.9999). The coefficient of variation for intra-day and inter-day accuracy and precision was less than 9.5%. The mean extraction recovery was 84.1%. Quality control samples were stable when kept at autosampler temperature for 24 h, at ?20 °C for 42 days and after three freeze-thaw cycles. The assay was successfully applied to a randomized, two-period cross-over bioequivalence study in 20 healthy Chinese volunteers following a single oral dose of 40 mg pantoprazole. Various pharmacokinetic parameters including AUC _0～t , AUC _0～∞, C _max, T _max and t _1/2 were determined from plasma concentration of both formulations. The results indicated that the analytical method was a specific, precise, sensitive and rapid procedure for determination of plasma pantoprazole concentration and therefore, a suitable and valuable tool in the investigation of the clinical pharmacokinetics and bioequivalence.     

Development and Validation of Atorvastatin by LC–ESI–MS and Application in Bioequivalence Research in Healthy Chinese Volunteers

The aim of this research was to develop a sensitive liquid chromatographic–electrospray ionization–mass spectrometric (LC–MS) method for direct measurement of the concentration of Atorvastatin in human plasma. Plasma samples (1 mL) were extracted with 3 mL ethyl acetate, and by a simple reversed-phase chromatography. Pitavastatin was used as internal standard (IS). The LOQ was 0.25 ng mL^?1 (RSD 4.24%). The assay was linear from 0.25–20 ng mL^?1. And the correlation coefficient for the calibration regression line was 0.9996 or better. Intra-day and inter-day accuracy were better than 15%. The method has been successfully used for a pharmacokinetic study with human subjects. A two-period crossover designed bioequivalence research was also progressed in healthy Chinese volunteers. Among the pharmacokinetic data obtained, T _max was 1.36 ± 0.68 h for reference formulation and 0.81 ± 0.54 h for test formulation. C _max was 8.54 ± 5.06 ng mL^?1 for reference formulation and 9.54 ± 3.68 ng mL^?1 for test formulation. t _1/2 was 8.50 ± 2.74 h for reference formulation and 9.24 ± 3.17 h for test formulation. AUC _0?48h was 54.77 ± 21.82 h ng mL^?1 for reference formulation and 55.66 ± 20.91 h ng mL^?1 for test formulation. The method was successfully applied to the study of pharmacokinetics of Atorvastatin in healthy Chinese volunteers.     

Simultaneous Determination of Ramipril and Its Active Metabolite Ramiprilat in Human Plasma by LC–MS–MS

A selective, rapid and sensitive liquid chromatography tandem mass spectrometry method has been developed for the simultaneous determination of ramipril and ramiprilat in human plasma using enalapril as the internal standard via one-step extraction with ethyl acetate under acidic condition. The analysis was carried out on a Diamonsil C₁₈ column (150 mm × 4.6 mm i.d., 5 μm) with a mobile phase consisting of 1% formic acid-acetonitrile (25:75, v/v) at a constant flow rate of 0.5 mL min^?1. The detection was performed on a triple-quadruple tandem mass spectrometer by selective reaction monitoring mode via electrospray ionization. Linear calibration curves of ramipril and ramiprilat were obtained in the concentration range of 0.107–107.0 and 0.262–105.0 ng mL^?1, respectively. The intra- and inter-day precision (RSD) values were below 8.2 and 4.8% for ramipril, 10.4 and 12.3% for ramiprilat, and accuracy (RE) were within ±5.5 and ±3.2%, respectively at all QC levels. The method was utilized to support clinical pharmacokinetic studies in healthy volunteers following oral administration of ramipril tablets.     

Comparison of electrical conductivity and thermal properties of borosilicate glass with and without simulated radioactive waste

Electrical conductivity and percentage linear thermal expansion of the borosilicate glass (BSG) and simulated waste-loaded borosilicate glass (BSGW) were measured in the temperature range of 300–780 K and compared. Pronounced increase in electrical conductivity was observed around glass transition temperature (T _g) of BSG and BSGW. The activation energy (E _a) of electrical conduction determined from the measured data for BSG and BSGW is 0.961 ± 0.005 and 0.960 ± 0.005 eV, respectively. The % average linear thermal expansion of BSGW showed a slight decreasing trend compared with pristine BSG. The average coefficient of thermal expansion determined from dilatometry data is 12.87 ± 0.24 × 10^?6 and 11.94 ± 0.23 × 10^?6 K^?1 for BSG and BSGW, respectively. The T _g measured by dilatometry is 806 ± 24 K for BSG and 790 ± 23 K for BSGW, respectively. The T _g measured by DTA was found to be 820 ± 7 and 805 ± 5 K for BSG and BSGW, respectively, for heating cycle. The T _g values obtained from DSC measurements are 805 ± 5 and 803 ± 5 K for BSG and BSGW, respectively. The T _g of BSGW showed a slight decrease compared with that of BSG. The values obtained by DSC examination also showed the lowering of T _g values for the waste-loaded composition. The lowering of T _g may be attributed to the interaction of glass-forming agents and simulated waste elements.     

Radiometric analysis of rock and soil samples of Leepa Valley; Azad Kashmir, Pakistan

In this article, we present results obtained from a radiometric survey that was conducted in the Leepa Valley of Azad Jammu & Kashmir, Pakistan. The purpose of current study is to appraise the radioactivity levels and the associated health hazards due to the terrestrial radionuclide in soil and rock samples. In this regard, 16 soil and 17 rock samples were collected from different locations of the Leepa Valley. After processing the samples, activity concentrations of primordial (²³²Th, ²²⁶Ra and ⁴⁰K) and anthropogenic (¹³⁷Cs) radionuclides were determined using a P-type coaxial high purity germanium detector. From the results obtained the mean activity concentrations of radionuclides ²²⁶Ra, ²³²Th and ⁴⁰K in the soil samples were found to be 31.25 ± 0.46, 44.1 ± 1.07 and 575 ± 8.89 Bq kg^?1 respectively. Whilst, in rock samples ²²⁶Ra, ²³²Th and ⁴⁰K mean activities were found as 28.46 ± 0.45, 48.63 ± 1.12 and 666.7 ± 9.39 Bq kg^?1, respectively. The ¹³⁷Cs concentration level in soil and rock samples is found to be 15.04 ± 0.29 and 5.7 ± 0.16 Bq kg^?1, respectively. The average radium equivalent activity (R _aeq) was found as 143.16 and 142.93 Bq kg^?1 in soil and rock samples, respectively. These findings are less than the recommended safe value of 370 Bq kg^?1 as given in OECD report (1979). The values of external (H _ex) and internal hazard index (H _in) are also less than unity. Mean value of absorbed dose rate was found as 69.78 nGy h^?1 for the soil samples, which is in good agreement with the world wide average value (70 nGy h^?1). Mean value of absorbed dose rate from rock samples was found as 70.01 nGy h^?1. Mean values of the annual effective dose is also lower than the values reported for different other countries of the world.     

Selenium content of Argentinean infant formulae and baby foods by pseudo-cyclic instrumental neutron activation analysis coupled to Compton suppression

The selenium levels of Argentinean infant formulae and baby food were measured using the 162-keV gamma-ray of ^77mSe (t _½ = 17.4 s) by a pseudo-cyclic instrumental neutron activation analysis (PC-INAA) method in conjunction with Compton suppression spectrometry (CSS). For comparison purposes, 5 selected infant formulae were also analyzed for selenium by a radiochemical neutron activation analysis (RNAA) method. The selenium levels for three samples agreed between ±2.8 and 6.5 % while the other two differed by 12 and 17 % which could perhaps be attributed to sample inhomogeneity. The selenium content of cow milk-based infant formulae varied from 42–146 μg kg^?1 compared to 52–63 μg kg^?1 for soy-based milk formulae. In the case of baby foods, the selenium levels varied from 34 to 74 μg kg^?1. The detection limits for selenium by PC-INAA–CSS for all the samples analyzed in this work were between 8.5 and 65 μg kg^?1 depending on the major elements present in the samples, while it was 20 μg kg^?1 for the RNAA method. The expanded uncertainty (κ = 2) of the PC-INAA–CSS method was 7.0 % at the end of cycle #4 for a sample containing 73.7 μg kg^?1 selenium compared to the RNAA value of 24.2 % for a sample of 67.0 μg kg^?1 selenium content.