Liquid Reference Materials Research Articles

Development of metal radioactive liquid reference material for proficiency test

This study developed liquid reference materials containing various metals, to be used for quality assurance of radiation measurements of the most common metallic wastes generated during the operation or decommissioning of nuclear power plants. The liquid reference materials were prepared by assuming the dissolution of stainless-steel using acid and melting of the major metals present in the stainless steel, namely Fe, Ni, Cr, and Mn, along with the standard sources (134Cs, 137Cs, 60Co, 90Sr). The theoretical massic activity of the standard sources added to the samples and the measured reference values of the gamma and beta emitters in the samples were compared, and they showed good agreement within a one-sigma confidence interval (k = 1). Using the developed reference materials, a proficiency test was conducted on three domestic labs, and the results were evaluated using Z-score. While the evaluation results showed good agreement between the reference values and the reported values for 137Cs and 60Co, all participating labs reported lower values than the reference value for 134Cs. For 90Sr, two out of the three labs reported significantly higher values than the reference value. Based on the results of this study, the developed metal radioactive liquid reference material is expected to be registered as certified reference material (CRM) in the future. They will be used as the CRM for measuring and ensuring the quality of radioactive metal waste.

Homogeneity evaluation of liquid reference material developed for nuclear decommissioning

Homogeneity assessment is explicitly required by ISO Guide 35. In connection with the INSIDER project, relevant reference material was chosen to be developed. For this purpose liquid material characterised for radionuclide content with accuracy better than 10% at the 95% confidence level and based on liquid effluent tank waste from JRC Ispra was produced by CMI and homogeneity of the selected radionuclides was evaluated.

Effect of pressure on the transport properties of 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide and 1-hexyl-3-methylimidazolium tetrafluoroborate

High-pressure self-diffusion and electrical conductivity data are reported for the ionic liquid reference material 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide. The data are used to calculate velocity cross-correlation coefficients and Laity resistance coefficients. High-pressure self-diffusion coefficients are also reported for 1-hexyl-3-methylimidazolium tetrafluoroborate. Comparisons are made with the viscosities using the Stokes-Einstein-Sutherland relation for the two ionic liquids. Density scaling is applied to the transport property measurements and comparison made with earlier studies on ionic liquid systems.

A homogeneous liquid reference material for monitoring the quality and reproducibility of in situ cosmogenic 10Be and 26Al analyses

Analysis of the in situ produced cosmogenic nuclides 10Be and 26Al has been used for several decades to study Earth surface processes; yet, no reference material has been widely adopted and used by the community to ensure the quality and comparability of sample preparation and isotopic analyses. Such a reference material could facilitate inter-laboratory comparison and serve as a benchmark for quantifying the accuracy, precision, and long-term reproducibility of terrestrial cosmogenic nuclide analyses. Here, we describe a liquid reference material, UVM-A, which is freely available to the community. We created four liters of solution by dissolving CRONUS-A granular reference material [1], and spiking the solution with stable 9Be and 27Al, yielding a solution containing 236.7 ± 0.6 μg g−1 Be and 932.6 ± 1.6 μg g−1 Al (average, 1SD). Initial analyses of UVM-A indicate that the nuclide ratios of the reference material (10Be/9Be 1.43 ± 0.02 × 10−13; 26Al/27Al 4.44 ± 0.05 × 10−13; average, standard error) are similar to those of late-glacial exposure samples, are tightly clustered, and match the nuclide concentrations expected from the CRONUS-A quartz used to prepare the reference material. Use of this reference material will help to quantify uncertainty in cosmogenic exposure ages, burial ages, and erosion rates resulting from sample preparation and isotopic analysis.

A Single-Line Single-Channel Method With Closed-Form Formulas for the Characterization of Dielectric Liquids

This paper presents a method for the measurement of liquid permittivity without using liquid reference materials or calibration standards. The method uses a single transmission line and a single microfluidic channel which intercept the line twice. As a result, two transmission line segments are formed with channel sections to measure liquid samples. In single-connection measurements, the scattering parameters of three transmission line states can be obtained. The three states are both segments filled with air, one segment filled with a liquid sample while the other with air, and both segments filled with liquid. By choosing a 2:1 ratio for the two line segment lengths, closed-form formulas are provided to calculate line propagation constants directly from measured S-parameters. Then, sample permittivity values are obtained. A coplanar waveguide is built and tested with deionized water, methanol, ethanol, and 2-propanol from 0.1 to 9 GHz. The obtained line performance agrees with the simulation results. The obtained sample permittivity values agree with commonly accepted values.

Electromagnetic Characteristics Measurement Setup at Variable Temperatures Using a Coaxial Cell

This article presents an easy way to measure frequency dependence of the complex permittivity and complex permeability for any kind of material from 10 MHz to 6 GHz, with temperature variation between the ambient temperature and 85°C. This work is based on a well-known transmission/reflection technique using a coaxial line equipped with a thermoregulation system to manage temperature variations in the sample confinement area. The paper underlines some effects which have to be taken into account with temperature variation. APU10 and cyclohexanol are presented as examples of solid and liquid reference materials.

Influencing factors of viscosity measurement by rotational method

Rotational rheometer was used to measure the shear viscosity of a liquid reference material of viscosity named GBW13604. The influences of heat balance time, bath temperature, environment temperature and sampling volume on results of measurements were investigated. Furthermore, a comparison of accuracy and repeatability of shear viscosity results between two commonly used systems with cone–plate and coaxial cylinder geometry was performed. Rheological tests indicate that the coaxial cylinder method is applicable to tests requiring high accuracy, while the cone-plate method is suitable for measurements that demand low sampling volume and fast speed.

Evaluation of different internal standards for precious metals quantification

The current study involved the evaluation of five different internal standards (Sc, Co, Y, In and La) as well as normal external or direct calibration methods in the simultaneous quantification of all six platinum group metals (PGMs) and gold (precious metals). The use of Sc as internal standard in the quantitative determination of precious metals in a liquid reference material (RM) and the geological Pyroxenite CRM was shown to yield excellent recoveries (> 99%) compared to the other metals used as internal standard in this study and the direct calibration method (> 91 %).Os recovered only 89% of the expected metal content. The evaluation of different proposed models (wavelength combinations, ionization and/or excitation energy) did not succeed in identifying or discriminating between the unsuccessful and successful internal standards. The robustness of the Sc internal standard addition method was evaluated with the variation in solution matrix (addition of HCl and NaCl). The analytical method (total metal recovery) proved to be very sensitive to elevated unmatched HCl matrix levels (above 1.0 mL of HCl (32% v/v) added) and Na+ addition larger than 4 ppm sodium using ICP-OES. KEY WORDS: Internal standard, Scandium, Precious metals, Spectrometric techniques, ICP-OES Bull. Chem. Soc. Ethiop. 2016, 30(1), 55-70.DOI: http://dx.doi.org/10.4314/bcse.v30i1.5

ICP-OES Monitoring of the Instability of [OsCl6]2− and Evaluation of [OsO2(CN)4]2− as Alternative Standard for Osmium Quantification

Abstract A spectrometric method using inductively coupled plasma optical emission spectrometry (ICP-OES) for the determination of Os and the stability of (NH4)2[OsCl6] standard was developed. Results obtained from this study showed a gradual decrease in Os recovery in the liquid reference material (RM) within 96 h of having prepared the calibration standards. The instability of the Os standard (NH4)2[OsCl6] resulted in the decrease in Os percentage recoveries. The Os calibration plots shifted (gained or lost sensitivity) after every 24 h. This gain or loss in sensitivity also varied, depending on acid or base used. In acidic medium, the gain in sensitivity of the calibration curves increased from HCl < HBr < HF whilst in the basic medium, the calibration plots decreased in sensitivity from NaOH < KOH < NH4OH. The stable Cs2[OsO2(CN)4] compound was synthesized and evaluated for its suitability as osmium standard and it was determined to be a good alternative standard for Os analysis due to its excellent stability in HCl matrix and at room temperature. The optimum storage conditions for both Os standards (NH4)2[OsCl6] and Cs2[OsO2(CN)4] and the liquid RM analyte solutions were in the acidic medium (HCl), in the dark and at ca. 10 °C.

Adiabatic Calorimetry as Support to the Certification of High-Purity Liquid Reference Materials

The certification of high-purity liquid reference materials is supported by several analytical techniques (e.g., gas chromatography, liquid chromatography, Karl Fischer coulometry, inductively coupled plasma mass spectrometry, differential scanning calorimetry, adiabatic calorimetry). Most of them provide information on a limited set of specific impurities present in the sample (indirect methods). Adiabatic calorimetry [1] complementarily provides the overall molar fraction of impurities with sensitivity down to few μmol · mol−1 without giving any information about the nature of the impurities present in the sample (direct method). As the combination of adiabatic calorimetry with one (or more than one) indirect chemical techniques was regarded as an optimal methodology, NMi VSL developed an adiabatic calorimetry facility for the purity determination of high-purity liquid reference materials [2]. Within the framework of collaboration with NMIJ, a benzene-certified reference material (NMIJ CRM 4002) from NMIJ was analyzed by adiabatic calorimetry at NMi VSL. The results of this measurement are reported in this paper. Good agreement with the NMIJ-certified purity value (99.992 ± 0.003) cmol · mol−1 was found. The influence of different data analysis approaches (e.g., extrapolation functions, melting ranges) on the measurement results is reported. The uncertainty of the measured purity was estimated.

Organic contaminants in water--conceptual considerations for the production of liquid reference materials in support of the new water framework directive.

The lack of suitable certified reference materials for the determination of organic pollutants in water has become a major problem within the framework of the new European water policy. This paper highlights approaches towards the production of certified reference materials and their drawbacks. On the basis of experience gained from proficiency-testing schemes, analytical practice, and reference material production a new concept for the production of liquid reference materials to be used in support of European legislation is presented and discussed briefly. The concept is based on a standard-addition approach and the simulation of effects interfering with the analytical process by use of individual matrix constituents or matrix-mimicking substances in combination with water-miscible solvents. The concept enables quantification of dissolved organic compounds in unknown water samples and evaluation of the analytical process with the help of a reconstituted sample. Open questions for further research are also outlined.

Method-dependent variations in the stability of apolipoprotein B in a stabilized liquid reference material

Using accelerated Arrhenius-type short-term and long-term temporal studies, we evaluated the storage life of a stabilized, liquid-frozen reference material (SLRM) for human apolipoprotein B (apo B) developed by the International Federation of Clinical Chemistry. As measured by our candidate reference RIA, the concentrations of immunoreactive apo B in the SLRM showed pronounced degradation with exposure to increasing temperatures over time. The SLRM was stable for as long as 1 year when stored at - 70 degrees C, but its immunoreactive apo B declined by < 10% when stored at 4 degrees C for 10 months. Using radial immunodiffusion and an ELISA to assess the equivalency of measured mass for the accelerated thermal stability of the SLRM, we found a loss of immunoreactive apo B similar to that measured by RIA. Analyzing the same samples by liquid immunoprecipitation (nephelometry) resulted in the amount of apo B present being overestimated, especially in samples held for long periods. By using different immunological methods to evaluate this thermally aged SLRM, we demonstrated that its measured behavior varies depending on the method of quantitation.