Reference Materials For Calibration Research Articles

Development and Validation of Polymer-based Porphyrin-Incorporated Reference Materials for Calibration of Quantitative Light-induced Fluorescence device

BackgroundThis study aimed at developing and validating polymer-based reference materials with varying amounts of porphyrin to accurately assess and calibrate quantitative light-induced fluorescence (QLF) device. MethodsReference materials with porphyrin concentrations ranging from 0 to 0.08 wt.% were prepared. The surface properties of the materials were analyzed via gloss and roughness measurements. Color analysis of the specimens was performed on black and white backgrounds with or without filters using a spectrophotometer. This approach revealed the correlations between fluorescence and color. The fluorescence emitted by the specimens was analyzed by measuring ΔR and ΔRmax values using a QLF-D BiluminatorTM. ResultsThe surface gloss and roughness of the reference materials were not affected by the porphyrin content (p > 0.005). Spectrophotometric measurements revealed significant color differences among most specimen groups depending on the background color and the presence of a filter. QLF-D imaging revealed significant differences in fluorescence (ΔR and ΔRmax) among all specimen groups regardless of the background. The fluorescence values observed on the black backgrounds were higher than those observed on the white backgrounds (p < 0.05). ConclusionsThe developed polymer-based porphyrin-incorporated materials serve as reliable reference standards for accurate assessment and calibration of QLF devices. This study demonstrates the importance of background conditions in fluorescence detection and highlights the potential of these materials as standards for QLF device calibration.

Discrepancies between two total IgE assays and difference in reference intervals in healthy adults

ObjectiveTo compare total immunoglobulin (Ig) E assay performance characteristics between Abbott Architect and Siemens Immulite test systems. Reference intervals were also determined for both platforms in an American population of healthy adults. MethodsAgreement of the two total IgE assays was evaluated in a cohort of 331 subjects with normal complete blood count (CBC) and comprehensive metabolic panel (CMP) results. Reference intervals were established in 302 subjects after exclusion of atopic individuals on the Abbott Architect and Siemens Immulite test systems. ResultsWe demonstrated a 32% positive bias for total IgE quantitation on the Siemens Immulite platform compared to the Abbott Architect, despite both methods calibrated against the same WHO international reference material (75/502), Furthermore, the upper limit of the reference interval (95th percentile) was determined to be higher for the Siemens Immulite assay compared to the Abbott Architect (132 and 102 IU/mL, respectively). ConclusionDespite the use of a common WHO reference material for total IgE assay calibration, significant differences in quantitation was observed between two FDA-cleared test systems. Given that, it is warranted for clinical laboratories to verify vendor established reference intervals and adjust accordingly based on internal assessment of the normal range.

Utilization of bis-MPA Dendrimers for the Calibration of Ion Mobility Collision Cross Section Calculations.

Ion mobility-mass spectrometry (IM-MS) has become increasingly popular with the rapid expansion of available techniques and instrumentation. To enable accuracy, standardization, and repeatability of IM-MS measurements, the community requires reliable and well-defined reference materials for calibration and tuning of the equipment. To address this need, synthetic dendrimers of high chemical and structural purity were tested on three ion mobility platforms as potential calibrants. First, synthesized dendrimers were characterized by drift tube ion mobility (DTIMS), using an Agilent 6560 IM-qTOF-MS to assess their drift tube collision cross section (DTCCS) values. Then, assessment of obtained CCS values on trapped ion mobility (TIMS) and traveling wave ion mobility (TWIMS) ion mobility platforms were compared to those found by DTIMS. Across all three systems, dendrimers were found to have high potential for m/z and ion mobility calibration in the CCS range of 160-1700 Å2. To further validate their use as calibrants, drift tube calculated CCS values for dendrimers were utilized to calibrate calculations of CCS for known standards including Agilent Tuning mix, the CCS Major mix from Waters, and SPLASH LIPIDOMIX. Additionally, structures of sodiated dendrimers were computated along with theoretical CCS values which showed good agreement with the experimental CCS values. On the basis of the results presented, we recommend the use of dendrimers as alternatives and/or complementary compounds to commonly used calibrants for ion mobility platforms.

A Set of Reference Materials for Verification and Calibration of Universal Chromatographic Instruments

Reference materials certified using State primary standards form the basis for ensuring metrological traceability to the corresponding measurement units. The article presents the results of the development of a series of new reference materials for the composition of pure organic substances, intended primarily for calibrating chromatographic equipment with various types of detection.The developed reference materials ensure traceability of the results of verification (calibration) of standards and measuring instruments, as well as measurement results in various areas of state regulation to ensure the uniformity of measurements. Certified values of reference materials were established by an indirect method – t he mass balance method. Metrological traceability of certified values is ensured by direct measurements on the State Primary Standard GET 208. Reference materials are pure substances packaged in glass ampoules (n-dodecane, n-heptane, n-hexadecane, benzene) or vials (hexachlorobenzene, lindane, reserpine, caffeine, glucose, sucrose, anthracene). The mass fraction of the main component of the reference material is in the range from 98.00 to 99.99 %, the relative expanded uncertainty (at k = 2, P = 0.95) does not exceed 0.5 %. The shelf life of reference materials is established by the accelerated aging method and is 3 years under recommended storage conditions.The article is of interest to industry specialists – metrologists, chemists, ecologists who control technological processes in various fields of activity, including the food and chemical industries, environmental protection, and scientific research.The described reference materials are commercially available to all interested parties.This study can provide empirical material for research in the field of serial production of reference materials, which can be used as a basis for the certification of other substances – similar organic substances.

50 Years of uranium isotopic reference materials at JRC-Geel

The history of uranium isotopic reference materials from JRC-Geel during the last 50 years is reviewed by presenting certification methods and relevant applications. The certified isotope ratios are traceable to the SI via gravimetrical preparation, either directly through gravimetrical mixing of highly enriched materials, or indirectly using existing gravimetrically prepared reference materials for calibration of mass spectrometers used for certification measurements. Due to developments of mass spectrometers and analytical methods, certification measurements have improved regarding precision, uncertainties and accuracy. This has led to a comprehensive set of uranium isotopic reference materials available for nuclear safety, security and the scientific community.

A-080 Overcoming Challenges of Equilibrium Dialysis-Based Free Thyroxine Measurements

Abstract Background Thyroid function tests are widely used to detect diseases of the thyroid. Concerns about the accuracy and reliability of free thyroxine (FT4) measurements have been stated by the clinical laboratory community. To address these concerns, CDC established a reference measurement procedure (RMP) for FT4 based on equilibrium dialysis (ED). ED-based methods have advantages over traditional direct immunoassays. As with all analytical methods, factors affecting accuracy and reliability of ED-based methods need identification and understanding. To investigate potential sources of error, the CDC FT4 RMP was used to evaluate T4 stability at different of storage conditions, adsorption of FT4 to common labware surfaces, and the effect of dialysis membrane materials on the measured FT4 in serum. Methods FT4 was measured in serum using the IFCC RMP (1). FT4 was separated from the protein-bound form during the equilibrium dialysis step of the RMP. Dialysates were spiked with internal standard (13C6-T4) and the analyte was further isolated by C18 solid phase extraction (SPE) and liquid-liquid extraction (LLE) in ethyl acetate prior to injection on an UHPLC system coupled with a triple quadrupole mass spectrometer. Bracketed calibration and primary reference materials were used to determine FT4 concentration in serum. This procedure was used to evaluate stability of serum FT4 during storage at −70 to 5 °C. Short- and long-term T4 stability of calibrator solutions at −70 °C to ambient temperature and the extent of adsorption of T4 calibrator solutions to the commonly used labware surfaces were evaluated. Furthermore, the suitability of 4 different dialysis membranes was assessed. In addition, three alternatives to the currently used SPE and LLE extraction steps were tested: LLE using cyclohexane and ethyl acetate, LLE with ethyl acetate, and supported liquid extraction with cyclohexane and ethyl acetate. Results T4 calibrator solution was stable in 1.7% ammonium hydroxide in ethanol for at least 2.9 years at −70 °C and up to 7 days at ambient temperature. Exposure of various calibrator solutions such as T4 in ethanol, ethanol with 1.7% ammonium hydroxide, 10% acetonitrile with 0.1% formic acid to common labware resulted in up to 10.1% loss of the analyte. FT4 in serum and T4 in dialysates and extracts were stable at −70 to 5 °C. Use of alternative dialysis membranes resulted in up to −8.8% mean bias to the reference membranes. Recoveries of the analyte using four extraction methods were 85.4%–95.0%. None of the tested extraction conditions significantly changed the results obtained with the original FT4 RMPs. Conclusion Although FT4 RMP must strictly adhere to the ED conditions described for the RMP, other parts of the sample preparation procedures can deviate from the originally published procedure. Careful selection of procedure for calibrator solvents, dialysis membranes, labware, and storage conditions is required to ensure accurate and reproducible FT4 measurements.

STDGL3, a Reference Material for Analysis of Sulfide Minerals by Laser Ablation ICP‐MS: An Assessment of Matrix Effects and the Impact of Laser Wavelengths and Pulse Widths

A new reference material, STDGL3, for the calibration of in situ analyses of sulfide minerals by LA‐ICP‐MS has been developed and characterised. It represents a lithium‐borate‐based glass containing a mixture of Zn‐ and Fe‐sulfide concentrates doped with several chalcophile elements as well as Zr, Gd, Hf and Ta required for assessing common interferences on Ag, Au and Pt. STDGL3 has a wider range of elements and a better homogeneity compared with existing reference materials for LA‐ICP‐MS analysis of sulfides. Compositional variations for most elements are below 3% RSD, below 5% RSD for Ag, Au and Pt, and below 7% RSD for Se, when performing spot analyses with a 50 μm beam size. Its preparation recipe is reproducible allowing for multiple batches to be made. Use of STDGL3 significantly improves accuracy of sulfide mineral analysis by LA‐ICP‐MS when compared with use of other available reference materials. Performance of STDGL3 was evaluated using several different laser systems. No significant change was observed between 193 nm ArF excimer lasers with 5 and 20 ns pulse widths, but use of 213 and 248 nm lasers displays more systematic differences, especially when analysing galena. Correction coefficients are needed for some elements (Zn and Cd in particular) when analysing sulfide minerals using STDGL3 as a calibration reference material.

Metrological Comparison of Available Methods to Correct Edge-Effect Local Plasticity in Instrumented Indentation Test.

The Instrumented Indentation Test (IIT) mechanically characterizes materials from the nano to the macro scale, enabling the evaluation of microstructure and ultra-thin coatings. IIT is a non-conventional technique applied in strategic sectors, e.g., automotive, aerospace and physics, to foster the development of innovative materials and manufacturing processes. However, material plasticity at the indentation edge biases the characterization results. Correcting such effects is extremely challenging, and several methods have been proposed in the literature. However, comparisons of these available methods are rare, often limited in scope, and neglect metrological performance of the different methods. After reviewing the main available methods, this work innovatively proposes a performance comparison within a metrological framework currently missing in the literature. The proposed framework for performance comparison is applied to some available methods, i.e., work-based, topographical measurement of the indentation to evaluate the area and the volume of the pile-up, Nix-Gao model and the electrical contact resistance (ECR) approach. The accuracy and measurement uncertainty of the correction methods is compared considering calibrated reference materials to establish traceability of the comparison. Results, also discussed in light of the practical convenience of the methods, show that the most accurate method is the Nix-Gao approach (accuracy of 0.28 GPa, expanded uncertainty of 0.57 GPa), while the most precise is the ECR (accuracy of 0.33 GPa, expanded uncertainty of 0.37 GPa), which also allows for in-line and real-time corrections.

Validation of efficiency transfer for high-density materials in HPGe spectrometry

Recycling and conventional reuse of lead materials and structures originating from controlled areas in nuclear facilities rely on historical knowledge and well selected characterization procedures. At the SCK•CEN, one of these procedures involves performing high-resolution gamma-ray spectrometry measurements on several cylindrical shaped test samples (50 mm diameter and approximately 5 mm thickness), obtained during the lead melting campaigns. The high density (11.3 g/cm³) of these samples is a challenge for radionuclide analysis by gamma-ray spectrometry since no such calibration sources nor reference materials are available. We used the efficiency transfer procedure, relying on regular standard sources available in our laboratory, to set up calibrations for this specific counting geometry. The method proves to be fit for purpose.

Bulk synthesis of conductive non-metallic carbon nanospheres and a 3D printed carrier device for scanning electron microscope calibration.

Herein, a facile method is proposed for the bulk synthesis of conductive non-metallic carbon nanospheres with controllable morphology to replace conventional metal calibration reference materials (CRMs), such as gold nanoparticles and copper grids. The prepared nanospheres had an average diameter of ∼222 ± 23 nm, where silicon dioxide formed the core and the shell was comprised of the carbon layer. The structure of the conductive carbon nanospheres was characterized using FTIR, SEM, EDS and TEM. Additionally, an innovative design was demonstrated by 3D printing the calibration carrier device. Furthermore, the stability and image linear distortion of the conductive carbon nanospheres were verified using analysis of variance (ANOVA). The results demonstrated that the accelerating voltage, magnification, and various positions in the X/Y axes had no significant effect on measured diameter of nanospheres, which was evident from all the p values being greater than 0.05. The comprehensive set of results reveal that conductive carbon nanospheres have great potential to replace traditional CRMs.

Calcite TLM and LSJ07 – two natural low-Sr reference materials for microbeam Sr isotope analysis

In situ microbeam Sr isotope analysis relies on the microanalytical homogeneity of reference materials (RMs) for calibration, method validation and data quality control.

Development of Reference Materials for Calibration of the Hydrogen Analyzer at High Concentration

The study discusses the issues of improving the accuracy of measuring high hydrogen concentrations in the development of storage materials in the hydrogen energy industry. The purpose of the study was to develop reference materials for calibration of the hydrogen analyzers at high concentrations. The main methods for determining the hydrogen content in materials were analyzed. It was established that the extraction method in an inert gas medium has found the widest application. The main methods for determining the hydrogen content in materials are analyzed, it is established that the extraction method in an inert gas medium has found the widest application. The need for calibration of analyzers on reference materials with a high hydrogen concentration was noted. Reference materials of titanium alloy VT-1-0 with hydrogen concentration up to (4.0±0.1) wt.% have been developed. The optimal parameters for the analysis were selected. On the example of the hydrogen analyzer RHEN602 (LECO, USA), calibration was carried out on the developed reference materials to obtain a calibration dependence. The reliability of the obtained calibration curve with the application of stoichiometric zirconium hydride was estimated. The confidence interval of the resulting calibration curve was ±10 %. It has been established that the calibration on the developed materials makes it possible to analyze materials with a hydrogen content of 0.5 to 4.0 wt.%. The practical significance of the study lies in the development of reference materials that can be applied to calibrate hydrogen analyzers operating on the principle of melting in an inert gas medium at a high hydrogen concentration.

Pitch calibration of standard nanoscale for uncertainty reduction of certified reference materials for SEM image sharpness evaluation and magnification calibration

Scanning electron microscopy (SEM) is widely used to observe and analyze nanostructures on surfaces. To obtain accurate and sharp images by SEM, it is necessary to evaluate the sharpness of SEM images and calibrate the magnification simultaneously. The NMIJ-CRM 5207-a is a certified reference material for image sharpness evaluation and magnification calibration. The certified values of NMIJ-CRM 5207-a are the average pitches in the X- and Y- axes. The major source of uncertainty of the NMIJ-CRM 5207-a is the pitch calibration of the commercially available standard nanoscale. To reduce the uncertainty of the pitch calibration value of the standard nanoscale, the pitch calibration was performed using a metrological atomic force microscope and uncertainty was evaluated in this study.

Analytical effect of stabilizer volume and shape on zircon U\u2013Pb dating by nanosecond LA-ICP-QMS

In this paper, we evaluated the effect of seven stabilizers with different shapes (including cylinder, cubic and ball shape) on zircon U–Pb dating analysis by laser ablation inductively coupled plasma quadrupole mass spectrometry (LA-ICP-QMS) in detail. In the case of stabilizer volume examined, the analytical efficiency of cylinder stabilizers (21.2, 25.1, 35.3 and 125 mL) were investigated in terms of signal stabilization, signal rising/washout time and U–Pb dating accuracy. By using zircon 91500 as reference material for external calibration, the 206Pb/238U age of zircon Plešovice was determined by a nanosecond LA-ICP-QMS, where the stabilizer was placed directly after the ablation cell and sample aerosols carried by helium passed through the stabilizer and subsequently mixed with make-up gas (argon) before ICP. It was found that transient signal oscillations were invisible and signal intensities were comparable using all the stabilizers, while signal rising time was 2.0-fold and washout time was 27.6-fold for stabilizer with volume of 125 mL to that of 21.2 mL. The obtained average 206Pb/238U age of zircon Plešovice was 335.53 ± 1.02, 361.73 ± 5.04, 340.10 ± 1.98 and 341.21 ± 5.17 Ma (2σ, n ≥ 5), respectively, giving average relative deviations of a single point of age (1σ) less than 2.0%. Among the corresponding 206Pb/238U ratios, it was also found that the value (0.05343 ± 0.87‰, 1σ, n = 5) obtained using 21.2 mL of cylinder stabilizer highly agreed with that of 0.05384 ± 0.74‰ (1σ, n = 5) using the commercially available “squid” stabilizer. The analytical efficiency of the 21.2 mL of cylinder stabilizer was then compared to that of cubic shape stabilizer (18.5 mL) and ball shape stabilizer (14.1 mL). Results showed that there were no significant differences of the obtained 206Pb/238U ages using stabilizers with volume in the range of 14.1–21.2 mL. But both cubic and ball shape stabilizers exhibited washout time over 270 s. We also studied the particle filter effect of the stabilizers by packing the 21.2 mL of cylinder stabilizer with 1.0 g of stainless wire. Despite the average 206Pb/238U age deviation was only − 0.81%, spiky signals occasionally occurred which might be ascribed to the use of a nanosecond laser and relatively low density of stainless wire in the stabilizer. This study confirmed that an empty stabilizer with volume of 21.2 mL and cylinder shape was preferred to produce smoothing signals. The improved analytical accuracy of zircon U–Pb dating using such a stabilizer ensured the future application to trace element analysis by LA-ICP-QMS.

Recent advances in the standardization of fluorescence microscopy for quantitative image analysis.

Fluorescence microscopy is a broadly used technique within a variety of different fields, including life sciences and medical research, and its quantitative aspects are becoming emphasized. The challenge now lies in improving the accuracy and precision of the measurements obtained from fluorescence microscopy. Improving these will facilitate the comparison of results between different instruments/institutions and therefore ensure the reproducibility of results. In this review, recent standardization procedures, including the benchmarking of the instrument performance and the standardization of the image itself, as well as the reference materials for calibration are summarized, and an overview of the advances in fluorescence microscopy standardization and the current limitations are presented. A procedure for the comparison of the image data obtained using different instruments, by different analysts and/or at different times, should be developed to improve the standardization of this data. The standardization of image data would lead to the development of new applications of fluorescence microscopy not only in academic research but also in regulatory science.

Use of Non‐Matrix Matched Reference Materials for the Accurate Analysis of Calcium Carbonate by LA‐ICP‐MS

Advances in laser ablation inductively coupled plasma‐mass spectrometry have improved analytical precision for mineral analysis, expanding geological interpretations from LA‐ICP‐MS results. However, with improvements in analytical precision, systematic errors from calibration can become more obvious and affect data quality. To improve the accuracy of the LA‐ICP‐MS technique, a fully quantified method is presented for the analysis of minerals with a CaCO3 matrix. An in‐house calcite sample (P‐Cal) was developed with an independently constrained composition and compared with measurement results from LA‐ICP‐MS analysis, generated using multiple spot sizes, laser fluences and calibration methods. For many elements, calibration against NIST SRM 612 as a calibration reference material and USGS GSD‐1G and USGS BCR‐2G as secondary reference materials (calibration B) provided the best accuracy for CaCO3 analysis. Ablation rates and element yield (ICP‐MS signal intensity in counts per second for a given isotope relative to the mass fraction of the respective element) in calcium carbonate closely resembles NIST SRM 612; however, the down‐hole fractionation curves of USGS BCR‐2G (basaltic glass matrix) are a better fit for carbonate. Variations in accuracy for measurements at different spot sizes are negligible compared with the other effects discussed. Additionally, ablation characteristics for powdered crystals versus large fragments produce a negligible effect on the accuracy of the results for calcium carbonate.

In situ element analysis of spodumenes by fs-LA-ICPMS with non-matrix-matched calibration: Signal beat and accuracy

In this work, in situ laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) analysis with non-matrix-matched calibration is proposed for determining the composition of spodumene samples. Accuracy of the quantification in dependence on instrument operating conditions and the signal beat effect on quantification accuracy have been investigated in detail. Using NIST SRM 610 as reference material for external calibration, the mass fractions of major, minor and trace elements (Li, Si, Al, Na, Mg, Mn, Fe, Ga, and others) were determined using femtosecond-LA-ICPMS and compared with nanosecond-LA-ICPMS. Helium (He) was employed as the carrier gas in the ablation cell, and the aerosols produced under hole drilling ablation condition are then transported to a quadrupole ICPMS by a mixture of He and Ar as the make-up gas. Results show that the carrier gas flow rate had a substantial effect on both transient signal structure and LA-ICPMS quantification. With different He flow rates, both synchronized and non-synchronized acquisition with and without aliasing in the transient signals recorded were compared. Synchronized acquisition settings could attenuate the oscillations in the transient signals substantially but showed large variability (up to 18% RSD for Li2O) among individual acquisitions. Non-synchronized acquisition, with and without visible aliasing, on the other hand, was producing reproducible results without systematic biases when averaging ion signals from a sufficient number of scans (>100) for quantification. For the latter it was found that non-aliasing methods allowed for a direct identification of heterogeneities or inclusions in the transient signals and these were thus preferred for analysis. The accuracy of the analyses with non-matrix matched calibration was evaluated by comparing the matrix Al2O3/SiO2 mass fraction ratios with those obtained by electron probe microanalysis (EPMA). It was found that operation with only 0.2 L/min of He achieved the best agreement, while higher gas flow rates caused an increase in Al2O3/SiO2 and Li2O/SiO2 mass fraction ratios. This is considered to be a result of differences in ionization efficiency within the ICP caused by the higher abundance of easily ionized elements in the spodumenes compared to the calibration standard. By selecting appropriate acquisition settings for sequential MS detection and robust operating conditions, the repeatability of the analyses could be improved to values less than 1% for the Li2O mass fractions determined. When using the proposed settings for the analysis of 11 spodumene samples of different origin, the Al2O3/SiO2 mass fraction ratios agreed within −2% to +4% to those obtained by EPMA. These results confirm that spodumenes can be accurately analyzed in situ by LA-ICPMS without matrix-matched calibration standards. While matrix elements of the studied spodumenes were all in a comparable range, minor and trace elements showed substantial intra- and inter-sample variabilities.

Characterization of Four Copper Materials for Application as Reference Materials for High Precision Copper Isotope Analysis by Laser Ablation Inductively Coupled Plasma Multi-Collector Mass Spectrometry

Laser ablation inductively coupled plasma multi-collector mass spectrometry (LA-MC-ICP-MS) allows rapid, in situ, highly precise measurements of Cu isotope ratios of native Cu and Cu-bearing minerals. However, the National Institute of Standards and Technology Cu-metal isotope standard NIST SRM976 that is commonly used to calibrate LA-MC-ICP-MS Cu isotope measurements of native Cu is no longer available. We have investigated the suitability of four Cu metal materials, SSC-1, SSC-3 and SSC-4 (cathode Cu metal rods) and CUPD-1 (Cu anode sawings), originally developed by the Canada Centre for Mineral and Energy Technology (CANMET) as certified reference materials for trace element analysis, as Cu isotope reference materials for LA-MC-ICP-MS analysis and solution nebulization (SN) of Cu. The Cu isotopic composition and homogeneity of these four materials were characterised by SN- and LA-MC-ICP-MS, and are reported for the first time. The bulk Cu isotopic compositions, expressed as δ65CuSRM976 in per mil (‰) relative to NIST SRM976 with combined uncertainties (U, k = 2), of SSC-1, SSC-3 and SSC-4, determined utilizing SN-MC-ICP-MS, are identical within analytical uncertainty at 0.03 ± 0.07‰ (n = 29), 0.04 ± 0.04‰ (n = 28), and 0.05 ± 0.08‰ (n = 29), respectively; the composition of CUPD-1 is 2.14 ± 0.08‰ (n = 28). The compositions are 0.01 ± 0.07‰ (n = 29), 0.04 ± 0.06‰ (n = 29), 0.03 ± 0.06‰ (n = 28) and 2.15 ± 0.06‰ (n = 28), respectively, relative to the European Reference Material ERM®-AE633 Cu isotope standard. The Cu isotope homogeneity of the four new reference materials was assessed by determining whether multiple individual in situ Cu isotope measurements made by LA-MC-ICP-MS analysis (43 µm spot size), using each of the other three reference materials as a calibrator, approximate a single normal distribution. We also investigate whether there are statistically significant differences between the mean δ65Cu values of three independent data sets for each of the Cu isotope reference materials using one-way analysis of variance (ANOVA). Normality tests (graphical assessment of normal distribution quantile-quantile plots, and the Shapiro-Wilk, Jarque-Bera and reduced chi-squared statistic tests) show that: 1) the Cu isotope data acquired on SSC-1, SSC-3, SSC-4 and CUPD-1 do not depart significantly from a normal distribution, 2) the scatter of the Cu isotope data is due to analytical uncertainty with 95% confidence, and 3) there are no other significant sources of scatter; e.g. heterogeneity of the reference materials. The results of one-way ANOVA reveal that the mean difference of the δ65Cu value for each of the reference materials SSC-1, SSC-3, SSC-4 and CUPD-1 is statistically not significant at the 0.05 level. The mean δ65CuSRM976 values with combined uncertainties (U, k = 2) of SSC-1, SSC-3, SSC-4 and CUPD-1, determined by LA-MC-ICP-MS using each of the other three reference materials as a calibration standard, are 0.03 ± 0.09‰ (n = 132), 0.05 ± 0.09‰ (n = 154), 0.03 ± 0.09‰ (n = 144) and 2.14 ± 0.10‰ (n = 106), respectively. These values are in agreement with those determined by SN-MC-ICP-MS analysis at the 95% confidence level and have excellent precision (2 s.d. ≤ 0.10‰). These results suggest that SSC-1, SSC-3, SSC-4 and CUPD-1 can be considered isotopically homogeneous at a spatial resolution of 43 μm, and they are suitable reference materials for calibration and quality control of in situ and solution nebulization Cu isotope analyses of Cu.

Serum Prostate-Specific Antigen Testing for Early Detection of Prostate Cancer: Managing the Gap between Clinical and Laboratory Practice.

Current clinical practice guidelines (CPGs) for early detection of prostate cancer recommend for clinical decision-making a personalized prostate-specific antigen (PSA)-based management to improve the risk-benefit ratio of the screening strategy. Some important critical issues regarding the PSA determination in the clinical framework are, however, still neglected in current guidelines and a major focus of recommendations on those aspects would be needed to improve their effectiveness. Evidence sources in the available literature concerning the interchangeability of total PSA results measured with different commercial methods were critically appraised. We discuss how the heterogeneity of the measurand, the intermethod bias, and the design and selectivity of immunoassays may affect the diagnostic accuracy of selected PSA thresholds, and how knowledge of the analytical characteristics of assays in service, such as the recognized PSA circulating forms and the cross-reactivity with PSA homologs, is basic for improving both clinical decision-making in cancer screening and the reliability of the clinical interpretation of results at the individual level. Current CPGs ignore the poor interchangeability of PSA results obtained from different assays and the substantial role of laboratory issues in clinical performance of PSA testing. Involved stakeholders should contribute to fill the existing gap by: (a) preparing commutable reference materials for immunoassay calibration; (b) providing analytical characteristics that may explain the different performance of assays; (c) deriving outcome-based analytical performance specifications for PSA measurement; and (d) giving more focus on laboratory items when CPGs are prepared.

A Modelling and Validation Approach for Predicting Particle Concentrations of Airborne Dust during the Filling Process of Cylindrical Silos

Traditionally, when undertaking feasibility studies for designing new storage facilities such as storage silos, engineers will extract design information from experiments and evaluate potential risks associated with health and safety, suitability design for reliable material flow, and quality of products. The simulation approach applied incorporates Computational Fluid Dynamics (CFD), and Discrete Element Modelling (DEM) approaches and experimental tests will be used for validating these simulation results. One important aspect related to handling fine and dusty materials (particles smaller than 100 microns) is the associated risk of dust explosions, which needs to be evaluated before the commissioning of storage silos; to evaluate the accumulation of fines during the silo filling process, simulations and experiments were conducted. Alumina and salt were used here as reference materials for calibration and the validation purposes. The validation efforts are significant due to the fact that the data that is accessible in simulations is vastly different to the accessible data in experiments, which is restricted by measurement techniques and equipment. Such restrictions are observed in the evaluation of particle concentrations in a large confined volume. A new methodology has been developed to evaluate concentrations in both simulations and experiments by employing a non-dimensional factor [k], here called “Concentration Rank Factor” (CRF). A significant finding of this research is that experiments and simulations can be compared using CRF. It has been found to be within 2% of the experiment averaged value of 0.64.