Comparison of the Precision and Accuracy of Digital Versus Analogue Gamma-Ray Spectrometric Systems Used in INAA for Evaluation of Homogeneity and Certification of Reference Materials of the IAEA

Performance of three commercial gamma-ray spectrometric systems was evaluated for precision and accuracy prior to use in characterization of reference materials. Two of the systems were based on fast processing of the analogue signal from the amplifier (EGG Ortec model 672) using a loss free counting module (Canberra model LFC 599) interfaced to one of two analog-to-digital converters (Canberra models 8713 or 8715). The third system was based on a digital signal processor (Canberra model DSP 9660). Performance of the systems was tested over a range of count rates up to a maximum of 70,000 counts per second (dead time up to 90%) using ⁶⁰Co and ¹³⁷Cs sources. Best resolution was achieved with an analogue system with ADC 8713. The analytical results obtained with the digital system show the lowest and well-quantified uncertainty.     

Further development of a cosmic veto gamma-spectrometer

The Comprehensive Nuclear-Test-Ban Treaty (CTBT) is supported by a network of certified laboratories that perform high-resolution gamma-spectrometry on global air filter samples for the identification of 85 radionuclides. At the UK CTBT Radionuclide Laboratory (GBL15), a novel cosmic veto gamma-spectrometer has been developed to improve the sensitivity of measurements for treaty compliance. The system consists of plastic scintillation plates operated in time-stamp mode to detect coincident cosmic-ray interactions within an HPGe gamma-spectrometer. This provides a mean background reduction of 75.2 % with MDA improvements of 45.6 %. The CTBT requirement for a ¹⁴⁰Ba MDA is achievable after 1.5 days counting compared to 5–7 days using conventional systems. The system does not require dedicated coincidence electronics, and remains easily configurable with dual acquisition of unsuppressed and suppressed spectra. Performance has been significantly improved by complete processing of the cosmic-ray spectrum (0–25 MeV) combined with the Canberra Lynx? multi-channel analyser. The improved sensitivity has been demonstrated for a CTBT air filter sample collected after the Fukushima incident.     

An automated method for the simultaneous measurement of azole antifungal drugs in human plasma or serum using turbulent flow liquid chromatography-tandem mass spectrometry

Azole antifungal drugs are important in the prophylaxis and treatment of invasive aspergillosis. Therapeutic drug monitoring may be indicated to (1) monitor adherence, (2) guide dosage and (3) minimise the risk of drug–drug interactions and dose-related toxicity. TurboFlow^TM technology offers online, automated sample preparation. An Aria Transcend^TM TLX-II coupled with a TSQ Vantage^TM MS was used. Centrifuged samples (25 μL) were mixed with internal standard solution (975 μL) and 30 μL injected directly onto a C18-P-XL TurboFlow column. Analytes were focussed onto a Phenomenex Gemini Phenyl analytical column and eluted using a methanol/water gradient (flow-rate, 0.8 mL/min). Analytes were monitored in selected reaction monitoring mode (two transitions per analyte, positive mode APCI). Calibration ranges were as follows: itraconazole, hydroxyitraconazole, and posaconazole 0.05–5.0 mg/L; voriconazole and fluconazole 0.1–10 mg/L. Total analysis time was 12 min. TurboFlow column recovery was >77% for all analytes. Calibration was linear (R ²?>?0.99) for all analytes. Inter- and intra-assay imprecision (% RSD) was <8% and accuracy (nominal internal quality control values) 90–105% for all analytes. The limit of detection was 0.01 mg/L for all analytes. No matrix effects were observed. This method is simple, robust and suitable for measuring these compounds at concentrations attained during therapy.     

Atmospheric deposition of 210Po and 210Pb in Malaysian waters during haze events

Biogenic burning as forest fire phenomena occurring from April to August each year in the Sumatra and Borneo islands are major sources of biogenic uranium–thorium decay series in marine systems. 30 samples were collected during the Ekspedisi Pelayaran Saintifik Perdana 2009 cruise (EPSP 2009 cruise) between 12th June and 1st August 2009 from the Straits of Malacca to the Sulu and Sulawesi Seas to study the effect of haze and the monsoon season on the deposition rate of ²¹⁰Po and ²¹⁰Pb in Malaysian waters. All samples were spiked with 1 ml of lead [Pb(NO₃)₂; 25 mg ml^?1] and 0.05 ml of Polonium-209 tracer (26.08 dpm ml^?1). ²¹⁰Po activity was determined by auto plating onto silver foil and counting using an alpha spectrometry system (Canberra model Alpha Analyst with a silicon-surface barrier detector). Lead that was collected via electrodeposition, formed lead sulphate (PbSO₄) precipitation. This precipitate was wrapped onto plastic discs and counted for ²¹⁰Pb beta activity using a gross alpha–beta counting system (Tennelec model LB-5100 low background gas-flowing anti-coincidence alpha/beta counter) after 1 month to allow bismuth ingrowths. The range of ²¹⁰Po activities varied between 51.08 ± 15.1 and 742.08 ± 220.34 Bq/kg, whereas the activity of ²¹⁰Pb ranged from 31.10 ± 4.20 to 880.23 ± 123.86 Bq/kg and ²¹⁰Po/²¹⁰Pb ratio value varied between sampling stations from 0.19 to 13.77. The contents of ²¹⁰Po were also statistically positively correlated with the amount of total suspended particulate especially those recorded during heavy haze period events.     

Determination of Ruscogenin in Turkish Ruscus L. Species by UPLC

Determination of ruscogenin in five Ruscus taxa in Turkey was performed by ultra performance liquid chromatography (UPLC). Chromatographic separation and determination of ruscogenin in herb and rhizome samples were accomplished on an Acquity UPLC^TM BEH C₁₈ (50 mm × 2.1 mm, i.d., 1.7 μm) column system using an isocratic elution with a mobile phase consisting of acetonitrile and water (90:10) (v/v) at a constant flow rate of 0.3 mL min⁻¹. Chromatographic calibration graph of ruscogenin in the concentration range of 22–55 μg mL⁻¹ was obtained by using the linear relationship between the concentration and the peak area measured at a wavelength of 200 nm. The method was validated and successfully applied to the quantitative analysis of the real samples containing ruscogenin of Ruscus species. The ruscogenin amount in the hydrolyzed herb of Ruscus aculeatus was higher than in the hydrolyzed rhizomes of Ruscus aculeatus. In the rhizomes of R. colchicus, R. hypoglossum and R. hypophyllum, the ruscogenin amount was higher than in the herbs.

     

Cosmogenic 22Na, 7Be and terrestrial 137Cs, 40K radionuclides in ground level air samples collected weekly in Kraków (Poland) over years 2003–2006

A low background gamma spectrometer with an Etruscan, 2500 years old lead shield and a muon veto detector were applied to study ²²Na and ⁷Be activity concentration in ground level air aerosol samples collected weekly over the years 2003–2006 in Kraków. Each sample was formed with ca 100 000 m³ of passed air, collected with two parallel ASS-500 high volume air samplers. The results for ⁴⁰K and ¹³⁷Cs are also presented for reference and comparison. Presented frequency distributions for activity concentration and correlation between the obtained results are discussed. The activity concentration results confirmed seasonal variation of activity to be different for all the investigated radionuclides. Moreover, the seasonal variation in nucleus activity ratio was also noticed for ²²Na and ⁷Be. Cosmogenic radionuclides being mainly of stratospheric origin, are subsequently attached to fine aerosols, via which they are transported to the ground level air. The mean aerosol transport time within the troposphere was estimated as equal to 7.5 days on average, reaching even 50 days in warm seasons. Limitations of the applied model were identified.     

Quantitative Determination of Anti-Inflammatory Columbianetin in Rat Plasma by LC-ESI-MS/MS for Pharmacokinetic Studies after Oral Administration of Duhuo Extract

Specific LC-ESI-MS/MS method or procedure was developed and validated for columbianetin quantification in rat plasma using epicatechin as an internal standard (IS). Chromatographic separation was performed on an Eclipse plus C18 (150 × 4.6 mm, 1.8 ??m) at a flow rate of 0.300 mL min^?1, and water-acetonitrile was used as mobile phase. The calibration curve of the method was linear in the concentration range of 5?C1,000 ng mL^?1. The lower limit of quantification (LLOQ) was 5 ng mL^?1. The intra- and inter-day precision of the quality control samples was within 15.0%, and the accuracy was within 90.0?C110%. The recoveries were more than 90.0% for columbianetin at concentrations of 10, 200 and 1,000 ng mL^?1, respectively. This method was successfully applied for evaluation of the pharmacokinetics of columbianetin after oral doses of 0.60 g kg^?1 Angelica pubescence extract in rats.     

Determination of depth of a radionuclide source in a tissue equivalent phantom

Hydrophilic materials which refer to a group of cross-linked polymers originally developed in the 60s to produce soft contact lenses are characterised by an equilibrium water uptake in the range 15–95 % by wet weight when hydrated in water or normal saline solution at 25 °C. This ability to absorb controlled amounts of water makes them suitable human tissue substitutes. Four types of hydrophilic materials of different composition and thickness were placed between a ²²Na calibrated point source and a single LaBr₃: Ce (5 %) detector (Saint-Gobain) at a fixed distance between source and detector. The scatter-to-peak ratio was determined by selecting five scatter angle windows between 25 and 50^° (467–376 keV), at 5^° intervals, to study how the ratio varied with attenuating material, thickness and composition. From photon spectra recorded a ‘best’ estimate of the depth of the source in the hydrophilic material was obtained by finding the most sensitive scattering window. Theoretical and practical models of the source-to-detector geometries are included and discussed.     

Scout™, a portable MCA system

Quantrad Sensor's hand-held multichannel analyzer (MCA), the Scout^TM, has evolved considerably from the initial licensing from Pacific Northwest Laboratories (operated by Battelle Memorial Institute for the U.S. DOE). The Scout^TM has grown into a flexible MCA system with alpha-, gamma-, X-ray and neutron detection capabilities with wide ranging applications. The development philosophy is discussed along with specific examples of design choices in areas such as manufacturability, upgradability, probe interchangability and software user interface. Recently introduced products include: software enhancements, additional probes, customized software and a second generation instrument, the Scout512^TM, that boasts increased capabilities. Future developments are also discussed.     

Complexation of Eu3+ with cone conformers of three substituted calix[4]arenes in nitrobenzene saturated with water

From extraction experiments and $ \gamma Accurate knowledge of the trace elemental concentrations in wheat and its products is of great importance from a nutritional point of view. In this study, six wheat samples were prepared from the agriculture research center of Arak named Sardari, Amir, MV-17, Batava, Karaj-2 and Alvand; they were analyzed by neutron activation method (NAA). In this method, Isfahan miniature reactor as a neutron source and relative NAA method has been used as the analysis type. In this design in order to record gamma spectrum the MCA system and high purity germanium detector were used. Finally, the concentration of the trace elements such as Br, K and Na value was determined for the Sardari, Amir, Alvand, MV-17, Batava, Karaj-2 wheat samples. The average concentration of trace elements in all wheat samples in the studied area are 2.41(0.8597?6.1175) mg kg^?1 for Br, 13.42(8.7063?24.696) mg kg^?1 for Na and 463.30(434.22?505.45) mg kg^?1 for K, respectively. These were compared with other reports results. This study has been conducted as the first time for this region.     

Monte Carlo and experimental efficiency calibration of gamma-spectrometers for non-destructive analysis of large volume samples of irregular shapes

A comparison of efficiency calibration of a HPGe gamma-ray spectrometer applied for non-destructive analysis of gamma-ray emitters in large volume samples of irregular shape is presented. The detector efficiency calibration was carried out during the analysis of cosmogenic radionuclides (⁶⁰Co, ⁵⁴Mn, ²²Na and ²⁶Al) in fragments of the Ko?ice meteorite. Fourteen meteorite fragments were available for the analysis with masses from 27 to 2,163 g. A reasonable agreement in the estimation of the HPGe detector efficiency was obtained using the Monte Carlo simulation GEANT 3 code, and the experimental calibration using radioactive standards mixed with iron–silica–copper powder housed in mock-ups of similar shapes as the original samples. The differences in the efficiency estimation obtained by both methods were within 10 %. It is recommended that the Monte Carlo simulation of the detector efficiency can be applied in routine analysis of gamma-ray emitters in large volume samples of regular or irregular shapes.     

Photoinduced charge separation of phenothiazine–platinum–naphthalene diimide triads linked by twisted phenylene bridges

Two triads (i.e., 3PTZ–Pt–MNDI and 10PTZ–Pt–MNDI) consisting of 3-phenothiazine (3PTZ) or 10-phenothiazine (10PTZ), bipyridine–diacetylide platinum complex (Pt), and naphthalene diimide (MNDI) chromophores linked by highly twisted biphenylene spacers have been prepared. The formation and decay of the charge-separated (CS) states in toluene were studied by use of picosecond and nanosecond laser photolysis via selective excitation of the Pt moiety. The time required for formation of the CS state, PTZ⁺–Pt–MNDI^?, from PTZ–³Pt*–MNDI was determined to be τ _CS = 280 ps for 3PTZ⁺–Pt–MNDI^? and τ _CS = 230 ps for 10PTZ⁺–Pt–MNDI^?. The lifetimes of the CS states were determined to be τ _CR1 = 75 ns (95 %) and τ _CR2 = 285 ns (5 %) for 3PTZ⁺–Pt–MNDI^? and τ _CR = 830 ns for 10PTZ⁺–Pt–MNDI^?. Formation and decay of the CS states are discussed in terms the Marcus theory and the spin-correlated radical pair mechanism.     

LC Analysis and Pharmacokinetic Study of Pachymic Acid After Intravenous Administration to Rats

A simple and sensitive high-performance liquid chromatographic method with UV detection was developed and validated to investigate the concentration of pachymic acid (PA) in rat plasma. The sample preparation was a liquid-liquid extraction and chromatographic separation was achieved with a Dikma Diamonsil^TM C₁₈ column (250 × 4.6 mm I.D.) with a C₁₈ guard column (8 × 4 mm I.D.) using a mobile phase consisting of MeOH-MeCN-aq. 0.45% H₃PO₄ (45:40:22) at a flow rate of 1.0 mL min^?1. The UV detection was at 210 nm. Standard curves were linear (r = 0.9998) in plasma over the concentration range of 0.5–50 μg mL^?1 and had acceptable accuracy and precision. Intra- and inter-day precisions expressed as the relative standard deviation (RSD) were 0.26–1.60% and 1.24–2.31%. The lower limit of quantification and lower limit of detection were 0.45 and 0.17 μg mL^?1. The method has been used successfully to study the pharmacokinetics of PA. After a dose of 30 mg kg^?1 by intravenous administration, the main pharmacokinetic parameters t _1/2, AUC_0-∞, CL, V_ss and MRT_0-∞ were 8.79 ± 6.80 h, 18.90 ± 9.39 μg h mL^?1, 0.53 ± 0.28 L h^?1, 5.60 ± 4.60 L and 12.58 ± 9.95 h, respectively.     

Reversed phase StrataTM-X resin as sorbent for automatic on-line solid phase extraction atomic absorption spectrometric determination of trace metals: comparison of polymeric-based sorbent materials

A novel on-line flow injection solid phase extraction method for the preconcentration of trace toxic metals prior determination by flame atomic absorption spectrometry (FI-SPE-FAAS) was developed. The potential application of the hydrophobic reversed phase co-polymer sorbent Strata^TM-X packed into an on-line microcolumn for the quantification of Cd(II), Pb(II), Cu(II) and Cr(VI) was demonstrated for the first time. The method was based on the on-line formation of metal complexes using sodium diethyl-dithiocarbamate (DDTC) and on the subsequent retention of them onto the sorbent material. The target analytes were completely eluted by methanol and, subsequently, directed to FAAS for quantification. All chemical and flow variables affecting the performance of the developed method were thoroughly studied and optimised. For a preconcentration time of 90 s and a sampling frequency of 28 h^?1, enhancement factors of 72, 140, 185, 63 and detection limits of 0.18, 1.6, 0.20 and 1.2 μg L ^?1 were obtained for Cd(II), Pb(II), Cu(II) and Cr(VI), respectively. The accuracy of the FI-SPE-FAAS method was evaluated by analysing certified reference materials as well as spiked environmental water samples. Furthermore, a comparative study of the analytical characteristics, the properties as well as the chemical structures of commercial polymeric based sorbent materials was employed. Strata-X sorbent was compared against Hypersep^TM SCX, Bond Elut® Plexa^TM PCX, Oasis-HLB^TM and Nobias^TM PA-1, regarding the adaptation in on-line FI-SPE-FAAS systems for metal determination, and herein presented.     

Epithermal instrumental neutron activation analysis in conjunction with anti-coincidence gamma-ray spectrometry for investigating iodine levels in Canadian foods

In order to reduce interferences from high activities of ²⁴Na, ⁵⁶Mn, ⁸²Br, and ³⁸Cl as well as to improve detection limits, precision, and accuracy of measuring iodine levels in biological materials, foods and diets in particular, an epithermal instrumental neutron activation analysis (EINAA) method in conjunction with anti-coincidence (EINAA-AC) gamma-ray spectrometry was employed. The Compton scattering background in the region of the 442.9-keV photopeak of ¹²⁸I was significantly suppressed by anti-coincidence counting. In order to validate the EINAA-AC method as well as to evaluate its broad applicability to diverse types of biological material, 17 NIST and IAEA reference materials containing very low to high levels of iodine as well as interfering elements were analyzed by the EINAA-AC method. The samples were irradiated in the cadmium-lined pneumatic site at a neutron flux of 2 × 10¹¹ cm^?2 s^?1 of the Dalhousie University SLOWPOKE-2 Reactor (DUSR) facility for 10 or 20 min followed by 1-min decay and 30-min counting. The detection limit for iodine by EINAA-AC was improved by a factor of 2–5 compared to EINAA depending on the sample matrix and other factors, and a limit of 3–5 μg kg^?1 was achieved for low-salt foods. We found the RSD to be about ±5 % above 200, increasing to ±10 % at 20, and then to greater than ±30 % at about 5 μg kg^?1 iodine levels.     

Kinetics of Na|CF<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> and Li|CF<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> systems

Properties of CF _x /Li and CF _x /Na cells were examined while using galvanostatic charging/discharging, electrochemical impedance spectroscopy and scanning electron microscopy (SEM). The capacity during the first cycle was as high as ca. 1000 mAh g^?1. Such an electrode is suitable for primary CF _x /Li and CF _x /Na batteries. SEM images of CF _x cathode showed that during discharging it was transformed into amorphous carbon and LiF or NaF crystals (of diameter of ca. 5–20 μm). These systems (C?+?LiF or C?+?NaF) cannot be reversibly converted back into CF _x /Li or CF _x /Na, respectively. Exchange current densities are between 10^?7 Acm^?2 and 10^?9 Acm^?2 when working with LiPF₆ and NaPF₆ electrolytes (1.12?×?10^?7 Acm^?2 and 6.82?×?10^?9 Acm^?2, respectively). Those values are low and indicate that the charge transfer process may be the rate-determining step. Activation energies for the charge transfer process were 57 and 72 kJ mol^?1 for CF _x /LiPF₆ and CF _x /NaPF₆ systems, respectively. Higher activation energy barrier for the CF/Na⁺?+?e^??→?C?+?NaF reaction results in lower observed exchange current density in comparison to the system with lithium ions.     

Spatial distribution of 7Be in soils of Lower Austria after heavy rains

The ⁷Be approach in estimating the erosion rates is based on the assumption that the deposition of ⁷Be fallout associated with the erosive event is spatially uniform. The objective of the present work was to verify this assumption by assessing the influence of heavy rainfalls on the ⁷Be spatial distribution in Seibersdorf soils, Austria. Incremental and bulk soil depth profiles were collected from a flat site, undisturbed for the last 9 months prior sampling and with no evidence of erosion or deposition after the occurrence of heavy rains (>30 mm day^?1). The mean value of the ⁷Be areal activities (Bq m^?2) measured at 10 different points from the selected area was 312 Bq m^?2. This value corresponded to a total rainfall of 295 mm within the last 5 months prior sampling, considering that the highest mass activity of ⁷Be at soil surface will decay below the minimum detectable activity after 5 months’ time. The resulted coefficient of variation had a value of 19 % showing acceptable spatial variability of ⁷Be fallout connected with individual storm events on a local scale.     

Ion Chromatographic Determination of Traces of Sodium,Magnesium and Chlorine in Gadolinium Nitrate

Abstract

Two independent and sensitive ion chromatographic methods with suppressed conductivity were developed for determination of traces of Cl, Na, and Mg in gadolinium-nitrate. Na-Mg was determined by cation-exchange column after matrix separation, whereas Cl was analyzed without matrix separation by high capacity anion-exchange column. Detection limit for Cl was 0.01 µg mL^?1 in sample solution and 1 µg g^?1 in solid sample. The reproducibility (100 µL injected) was better than 3%, 3% and 4% at 50, 25 and 50 µg L^?1 level for Cl, Na, and Mg respectively. The overall precision was better than ±7% for Na-Mg and ±5% for Cl.     

Simultaneous determination of60Co,131I and137Cs in model radioactive waste water by reverse radiometric flow injection analysis with the aid of a multichannel analyzer

Reverse radiometric flow injection analysis was used for the simultaneous determination of⁶⁰Co,¹³¹I and¹³⁷Cs in model radioactive waste water. A NaI (Tl) scintillation detector coupled to a Canberra MCA was used for measuring the activity of¹³⁷Cs at 662 keV,⁶⁰Co at 1173 keV and 1332 keV, and¹³¹I at 364 keV.     

Measurement of activity concentration of primordial radionuclides in soil samples from Thirthahalli taluk and the assessment of resulting radiation dose

The activity concentration of primordial radionuclides ²²⁶Ra, ²³²Th, and ⁴⁰K in soil samples of Thirthahalli taluk were measured systematically by using a low background HPGe detector coupled to 16 K MCA. The measured activity concentration of ²²⁶Ra lies between 5.1?±?0.2 and 79.5?±?1.7 Bq kg^?1with an average activity of 25.99 Bq kg^?1, ²³²Th ranges from 5.1?±?0.3 to 95.3?±?2.2 Bq kg^?1with an average activity of 33.60 Bq kg^?1and that of ⁴⁰K varies from 18.3?±?1.5 to 833.4?±?17.5 Bq kg^?1with an average activity of 175.52 Bq kg^?1. Higher concentration of these radionuclides were found in the soil samples where the regional geology is granites. The consequential gamma dose and the corresponding radiation hazard was also estimated and is found to be within the permissible limits. The possible radiological impact on the public was also determined and these results are presented in this paper.