Determination of caesium-137 in fast-reactor coolant systems

A method for the separation of caesium by ion-exchange involving ammonium 12-molybdophosphate has been investigated, and found to be 100% efficient for aqueous solutions with high sodium and potassium concentrations.     

Radiochemical determination of caesium-137 in liquid milk

Summary A simple and rapid method is described for the radiochemical determination of a caesium-137 in liquid milk. After the addition of caesium carrier the milk sample is deproteinized with nitric acid, filtered and alkaline earths removed by oxalate precipitation. From the decanted solution caesium is precipitated with sodium cobaltinitrite, separated from potassium as caesium silicotungstate and finally counted as dipicrylaminate by an anticoincidence beta counter. The radiochemical yields for caesium amount to about 65%. Good agreement is found between results obtained by the present method and by the gamma spectrometry. The results for caesium-137 content may be obtained within 6 hours.

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Zusammenfassung Es wird eine einfache und schnelle Methode zur radiochemischen Bestimmung von Caesium-137 in flüssiger Milch beschrieben. Die zu untersuchende Milch wird nach Zusatz des Caesiumträgers mit Salpetersäure enteiweißt. Aus der dekantierten Lösung werden die Erdalkalien als Oxalate abgeschieden. Das Radiocaesium wird mit Natriumnitritocobaltat gefällt, von Kalium mit Silicowolframsäure getrennt und endlich als Caesiumdipikrylaminat in einem Beta-Antikoinzidenzzähler gemessen. Die Caesiumträgerrückgewinnung beträgt durchschnittlich 65%. Die nach der beschriebenen Methode erhaltenen Resultate stehen in guter Übereinstimmung mit denen der gammaspektrometrischen Bestimmung. Der Radiocaesiumgehalt in Milch kann innerhalb von 6 Std bestimmt werden.

     

Determination of caesium-137 soil-to-plant concentration ratios for vegetables in Goiania City,Brazil

The radiological accident that occurred in Goiania City, Brazil, in September 1987, led to the spreading of¹³⁷Cs in the urban area. Even after the decontamination procedure, there was a reminiscence of¹³⁷Cs activity in the soil of residential gardens. This activity was enough to conduct preliminary experiments for determination of soil to vegetable concentration ratios. Experiments were conducted for carrots, lettuce and radishes. Two types of experimental patterns were used to determine the concentration ratios: lysimeters cultivation under greenhouse condition and soil cultivation in open field plot. The concentration ratios measured for cultivation under greenhouse and field plot conditions are considerably higher than those mentioned in the International Union of Radioecologist (IUR) data bank for the same vegetables and cultivation condition.     

Electrochemical determination of nitrite in water samples using a glassy carbon electrode modified with didodecyldimethylammonium bromide

Multiwalled carbon nanotubes were used as solid phase extraction (SPE) adsorbent for the determination of four chloroacetanilide herbicides (alachlor, acetochlor, metolachlor and butachlor) in water. The primary factors that influence the efficiency of the SPE performance, such as the amount of the adsorbent, the eluent solvent, the pH and the sample volume, were investigated and optimized. Under optimized conditions, the recoveries of the four herbicides at three spike levels were in the range 76.7–104.4%, and the RSDs ranged from 2.5–12.7%. Good linearity was obtained for the pesticides in the concentration range 0.0025–2.5 mg L^?1, and the detection limits were 0.01–0.03 μg L^?1 at signal-to-noise ratios of 3:1. The method was successfully applied to the determination of these analytes in tap water and river water.     

Determination of gold in water samples using electromembrane extraction

In this work, an electromembrane extraction (EME) technique was used for the extraction and determination of gold from water samples prior to UV-Vis spectrophotometry. An artificial neural network (ANN) combined with imperialist competitive algorithm (ICA) has been applied to optimize the EME. The effective parameters including pH of acceptor phase, extraction time (t), volume of sample solution (V), stirring rate (S), and voltage (E) were chosen as input variables and the extraction recovery of gold was considered as output variable. The mean of squared error (i.e., 0.0009) and determination coefficient (i.e., 0.9821) were applied to estimate the performance of the ANN model. The limit of detection was 4.5?µg L^?1 (S/N?=?3) on the optimized variables. The intra- and interday precisions (%) were found to be 6.7% and 2.6%, respectively. This technique was then applied for analysis of gold from environment water samples.     

Determination of linuron in water and vegetable samples using stripping voltammetry with a carbon paste electrode

A carbon paste electrode was used for the electrochemical determination of linuron concentrations in water and vegetable extracts. Optimal conditions were established with respect to electrode activation (electrochemical pretreatment), time accumulation, potential accumulation, scan rate, and pH. The limit of detection achieved with a pre-concentration step was 23.0 μg L⁻¹. Recovery measurements in vegetable extract and natural water samples were in the range of 98-103%, indicating that the proposed electrochemical method can be employed to analyze linuron in these matrices. The determination results were in good agreement with HPLC results.     

Determination of sulfonamides in milk samples by HPLC with amperometric detection using a glassy carbon electrode modified with multiwalled carbon nanotubes

A sensitive and accurate method for determining five sulfonamides based on HPLC with amperometric detection and using a glassy carbon electrode modified with multiwalled carbon nanotubes is proposed. Optimal conditions for the quantitative separation of selected sulfonamides were studied, and glassy carbon electrodes with and without modification with carbon nanotubes were systematically investigated as electrodic materials. Statistical analysis of the obtained results demonstrated that these modified electrodes achieved considerably better stability and sensitivity than the conventional unmodified ones. Detection limits were in the 1.2–6.0 ng/mL range. The usefulness of the method was demonstrated by the analysis of milk samples, taking into account the European legislation on residues in food products, following both a screening method to classify the samples and a confirmation method to provide more detailed information in the case of positive samples.     

Determination of nitrate in mineral water and sausage samples by using a renewable in situ copper modified electrode

A new approach for in situ electrodeposition of a renewable copper layer onto a copper electrode is reported. The active surface was obtained by anodic dissolution of a copper electrode at an appropriate potential and further redeposition of copper ions still remaining at the diffusion layer. Under optimal experimental conditions the peak current response increases linearly with nitrate concentration over a range of 0.1-2.5 mmol L⁻¹. The repeatability of measurements for nitrate was evaluated as 1.8% (N = 15) and the limit of detection of the method was found to be 11 μmol L⁻¹ (S/N = 3). Nitrate contents in two different samples (mineral water and sausages) compared well with those obtained from using the standard Griess protocol at a 95% of confidence level measured by the t-student test. The interference from chloride on the nitrate analysis and the possibility of simultaneous determination of nitrite were also examined.     

Determination of gold using clay modified carbon paste electrode

Sorption of gold(III) chlorocomplexes was studied by means of a carbon paste electrode modified with montmorillonite. Anionic exchange behavior was found in chloride media with low ionic strength. Anionic sorption of [AuCl4]- can be used as a preconcentration step to the determination of Au(III). Linear calibration dependences were found in the concentration range 4.06 x 10(-6) - 1.22 x 10(-5) mol/L Au(III) after 5 min of sorption and in the range 8.12 x 10(-7) - 6. 1 x 10(-6) mol/L after 10 min of sorption. Interferences of several anions and cations were studied. Model samples of table water were analyzed.     

pharmaceutical and biological samples using modified multiwall carbon nanotubes paste electrode

A carbon paste electrode(CPE) chemically modified with multiwall carbon nanotubes and ferrocene(FC) was used as a selective electrochemical sensor for the simultaneous determination of trace amounts of cysteamine(CA) and folic acid(FA).This modified electrode showed very efficient electrocatalytic activity for the anodic oxidation of CA.The peak current of differential pulse voltammograms of CA and FA increased linearly with their concentration in the ranges of 0.7-200μmol/L CA and 5.0- 700μmol/L FA.The detection limits for CA and FA were 0.3μmol/L and 2.0μmoI/L,respectively.The diffusion coefficient(D) and transfer coefficient(α) of CA were also determined.These conditions are sufficient to allow determination of CA and FA both individually and simultaneously.     

Adsorption of some toxic elements from water samples on modified activated carbon,activated carbon and red soil using neutron activation analysis

A simple and sensitive method for the determination of some metalloids and heavy metals in water samples is presented. The method is based on the preconcentration of the attachment of chelating functionalities with metalloids and toxic metals irreversibly and targeted towards toxic metals adsorbed on modified activated carbon, activated carbon and red soil particles at pH 3.0–9.0±0.2, followed by quantitative determination using instrumental neutron activation analysis (INAA), on the absorbers. Attachment results from attraction that may be physical, chemical, electrical, or a combination of all three. The efficient removal of metalloids and toxic metals, especially arsenic, chromium and mercury is anticipated. The adsorption capacity of the chemically modified activated carbon materials was evaluated for the above mentioned metalloid and toxic metal ions in the presence of iron ions and simulated water samples. Red soil particles containing iron was utilized in the control of oxidation-reduction reaction with metalloids and toxic metals. The preconcentration of the elements of interest on red soil particles, activated carbon and modified activated carbon at different depths, pH and oxidation states was investigated. The results obtained showed good agreement with certified values giving relative errors of less than 10%.     

乙酰二茂铁修饰碳糊电极测定废水中对氨基苯酚

利用线性扫描溶出伏安法研究了对氨基苯酚(PAP)在乙酰二茂铁修饰碳糊电极电化学行为。结果表明:在磷酸盐缓冲溶液(pH3.2)中,该修饰电极对PAP具有较好的催化活性,其峰电流与PAP浓度在7.0×10-7～3.0×10-5mol/L范围内呈线性关系,检出限为1.0×10-7mol/L(S/N=3)。利用该法测定了模拟水样中PAP的含量。     

Determination of thallium in water samples

This article illustrates the developments of effective preconcentration techniques and highly sensitive detection methods for accurate measurements of Tl species at extremely low concentration in aqueous solutions. The literature on this topic was taken from the Analytical Abstracts in the period 1990-2005.     

Determination of aromatic amines in environmental water samples using solid-phase extraction modified with sodium dodecyl sulphate and micellar liquid chromatography

Extraction and determination of seven aromatic amines in environmental water samples were performed with solid-phase extraction (SPE) and micellar liquid chromatography (MLC) using experimental design. Extraction of aromatic amines was carried out with a C₁₈ cartridge modified with sodium dodecyl sulphate (SDS). The washing solution and elution solvent for extraction of aromatic amines were aqueous solution containing 5% (v/v) acetonitrile and 5% (v/v) acetone and 3 mL methanol, respectively. The chemometrics approach was applied for the separation optimisation of these compounds using MLC. Different mobile phase compositions were used for modelling based on retention times to obtain the best separation using central composite design. The optimum mobile phase composition for separation and determination of analytes in water samples was 69 mM SDS, 9% v/v 1-propanol and pH = 6.4. Recoveries were between 84.8–93.5% with relative standard deviation (RSD) less than 5.8% (n = 5). Limits of detection and linear range were 1–4.5 and 3.1–125.0 µg/L, respectively. The proposed method was applied to determine the aromatic amines in real samples (river and well waters). Amount of 4-nitroaniline and 3-nitroaniline in river water sample were 2.15 and 1.91 µg/L, respectively.     

Determination of cesium-137 in water by ion exchange

The preparation of ammonium molybdophosphate (AMP) precipitated directly into the IRA-900 resinous structure and their application to the determination of cesium-137 in waters are described. The sample of water is passed through the resin, which retains the cesium. After the removal of strontium-90 and potassium-40 with 0.1M ammonium nitrate solution, the cesium is eluted with 1M sodium hydroxide solution. The AMP dissolved in the alkaline solution is used to precipitate the cesium by acidifying the solution.     

Effects of topography on caesium-137 in montane peat soils and vegetation.

This study investigated the relationship between altitude and 137Cs fallout in soils and plants. The soils and plants, Calluna vulgaris, Erica cinerea and Molinia caerulea, were sampled across a transect of two valleys in north-western Ireland. The results provided evidence that greater 137Cs deposition to soils occurred at higher altitudes, and the data supported the findings of a previous investigation in the same area. A valley effect, whereby greater concentrations of 137Cs accumulated in plants on the lower altitudes of the valley floors, was shown to be significant. Deposition values for total 137Cs in soils were not correlated with plant concentrations, although a relationship between concentrations in C. vulgaris and M. caerulea was found to be statistically significant. No relationship was observed between the 137Cs from weapons fallout with that of Chernobyl origin in the 0-10 cm depth soils, although a significant correlation emerged between the same two components measured in C. vulgaris. The results suggest that existing definitions of concentration ratios and transfer factors are, for many reasons, inappropriate for studies of soil to plant transfer of 137Cs in peatland ecosystems.     

Determination of40K and137Cs concentration in selected honey samples

Seventeen honey samples collected at different sites during 1992 have been measured using the method of -spectroscopy. Measurements were performed by a low background high purity germanium spectrometer of a relative efficiency of 14.5% and an energy resolution of 1.7 keV. Using natural -ray sources to determine efficiency, it has been shown that out of 17 samples of natural honey only two (of meadow type) have specific activity of¹³⁷Cs greater than 0.5 Bq kg^–1. The remaining samples have the same¹³⁷Cs concentrations as before May, 1986. Predominant activity in all samples comes from the⁴⁰K radionuclide, indicating natural honey.     

Determination of aluminium in natural water samples

The atmospheric deposition of terrestrial dust into the ocean is an important factor in controlling Earth's climate. Aluminium can be used as a tracer for the magnitude and location of dust transported from the land to surface ocean. The element is ideal for this purpose since its primary input is via aeolian dust deposition and it has a short surface water residence time. The accurate determination of dissolved aluminium in seawater is difficult due to the complexity of the matrix and the trace (nanomolar) concentrations at which the metal exists. This paper presents a critical review of the different sampling and analytical methods for the determination of the concentration of aluminium in natural waters, with particular focus on techniques successfully applied to shipboard analysis of seawater.