Characterized Reference Materials Research Articles

Introduction to qualification and validation of an immunoassay.

Immunoassays play an important role in drug development of products targeting the immune system. Consistent quality of the results from an immunoassay is essential to make unbiased and accurate claims about the drug product during preclinical and clinical development stages. Assay qualification and validation shed light on the performance of the assay. It is the first evaluation and the verification, respectively, of the assay's performance. This tutorial explains and illustrates the calculation methodology for important assay qualification parameters including precision, relative accuracy, linearity, the lower limit of quantification (LLOQ), the upper limit of quantification (ULOQ), the assay range and dilutability. This tutorial focuses on assays used for (pre-) clinical purposes, characterized by a lognormal distribution of the measurements on its original untransformed scale and by the lack of well characterized reference material. Statistical calculations are illustrated with qualification data from an enzyme-linked immunosorbent assay (ELISA) vaccine immunoassay.

Development and validation of a next-generation sequencing panel for clinical pharmacogenetics

The rapid clinical implementation of next generation sequencing techniques is due to its ability to sequence a large number of genetic regions at lower costs than conventional techniques. However, its use in the field of pharmacogenetics is still very limited. ObjectiveDesign, development, implementation and validation of a clinical pharmacogenetics next-generation sequencing panel. MethodWe developed a panel of hybrid capture probes (SureSelect®) for the analysis of the genetic regions of clinical interest collected by literature search and using Illumina HiSeq 1500® sequencing platform. We developed a bioinformatic algorithm for variant annotation, haplotype inference and determination of structural variants in the genes of interest. The results obtained were validated with Coriell® reference material from the pharmacogenetic repositories. ResultsThe developed panel allows the study of a total of 12,794 regions comprised in 389 genes. Validation results showed a sensitivity greater than 99% for single nucleotide variants and small INDELs. Haplotype imputation was consistent with the consensus results in the characterized reference materials. Furthermore, the developed tool was able to correctly identify different types of CYP2D6 copy number variations as well as a wide variety of HLA-B alleles. ConclusionsThis technology represents an appropriate alternative for its clinical use with advantages over conventional techniques in its throughput and complex gene study capabilities (CYP2D6, HLA-B).

Characterization of reference materials for in situ U–Pb dating of columbite group minerals by LA-ICP-MS

A new ID-TIMS 206Pb/238U age of Coltan139 is reported. Newly characterized reference materials (ZKW and DDB) are introduced for in situ U–Pb dating of columbite group minerals by LA-ICP-MS.

Development of Measurement Procedures for the Characterization of Reference Materials for Carbohydrate Composition of Dairy Products

This article studies the development of measurement procedures based on various methods for a comprehensive analysis of the carbohydrate composition of food systems. The basis of the primary reference measurement procedure (PRMP) is the method of iodometric titration based on the ability of iodine to oxidize aldosaccharides to the corresponding uronic acids in an alkaline medium. The accuracy of the PRMP was improved by optimizing the measurement parameters, including the method of high-performance liquid chromatography with refractometric detection (HPLC/RD), and by establishing their possible variation limit based on a multifactorial experiment. The application of the PRMP made it possible to measure the mass fraction of carbohydrates (total sugar) as the sum of the mass fractions of reducing and non-reducing sugars in milk and dairy products, grain and milk products, low-lactose and lactose-free products, including those used for preparing baby food. In order to further detail the carbohydrate composition, highly selective methods were developed for measuring the mass fractions of lactose and galactose by the spectrophotometric (enzymatic) method, and the mass fractions of mono- and disaccharides by the HPLC/RD method in milk and dairy products. It was found that the measurement results of both the total content of carbohydrates and individual mono- and disaccharides in the samples of milk and dairy products obtained by various methods (iodometric titration, HPLC/RD, enzymatic method, refractometry, IR spectroscopy, calculation method) are consistent with each other subject to the stated uncertainties. Thus, the applicability of the developed PRMP in combination with other methods for conducting an in-depth analysis of the carbohydrate composition of milk and dairy products was confirmed. The developed procedures were used to characterize reference materials for the composition of dairy products (3 types), mono- and disaccharides (9 types).

Abstract 1024: The challenge of standardizing the measurement of an imprecise biomarker like HRD

Abstract Here we present data on the characterization and implementation of a set of reference materials for the standardization of homologous recombination deficiency (HRD) assessment. The safety and effectiveness profile of a drug can be improved by using it in patients where that drug is most likely to be effective. While PARP inhibitors are indicated for use in some patients with ovarian, breast, pancreatic, and prostate cancer, patients with other cancers that are deficient in homologous recombination repair (HRR) might also benefit from their use. However, determining whether a cancer is HRD-positive is neither trivial nor precise. While clinical trials have shown that patients with deleterious mutations in BRCA2 and BRCA1 are most likely to benefit from PARP inhibitors, determining that a given BRCA mutation (or set of such mutations) is in fact deleterious is frequently not straightforward. Therefore, assays are now looking for signs of HRD, such as genomic instability consistent with non-homologous end joining (NHEJ) being used for the repair of double-stranded breaks in DNA as opposed to HRR. For example, some assays look at the combination of loss of heterozygosity (LOH) and large-scale state transitions (LST) across chromosomes as well as telomeric allelic imbalance (TAI) when determining whether a cancer is HRD-positive, while other assays use alternative approaches. How those characteristics are measured, integrated, and distilled into a final determination of whether HRD is present or absent varies, which can create uncertainty around treatment options and enrollment into clinical trials. This also makes the path of follow-on companion diagnostics challenging because perfect agreement between imprecise measurements is unlikely. In order to enable more standardized reporting of HRD and to enable the assessment of HRD assays, we created a set of characterized reference materials composed of HRD negative, borderline, and positive tumor/normal matched cell lines that were analyzed using both array-based and next generation sequencing-based assays in order to characterize chromosomal changes across their genomes and obtain HRD scores. Because of differences in the results, assay imprecision should be taken into account in clinical trials that implement cutoffs in order to establish safety data for patients who are biomarker-negative but may be biomarker-positive in a future assay, which is similar to what is done for complementary diagnostics. Citation Format: Yves Konigshofer, Matthew G. Butler, Krystyna Nahlik, Dana Ruminski Lowe, Catherine Huang, Omoshile Clement, Russell K. Garlick. The challenge of standardizing the measurement of an imprecise biomarker like HRD [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1024.

Matrix effects during in situ U-Pb dating of perovskite with variable crystal structure: Evidence from the Tazheran Massif, Russia

U-Pb geochronology of perovskite is one of the most reliable means of dating notoriously difficult to date and economically important kimberlites, carbonatites, and skarns. Matrix effects—isotopic variations due to chemical composition and crystal structure—are known to affect in situ U-Pb dating, but have not been documented in perovskite. Perovskite from the Tazheran Massif, Russia, has become a commonly used standard for U-Pb dating, so rigorously testing its general applicability is therefore critical. In this study, comparison between U-Pb ages generated by precise isotope dilution-thermal ionization mass spectrometry (ID-TIMS) and in situ dating methods including both secondary ion mass spectrometry (SIMS) and laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) for a series of perovskite crystals from the Tazheran Massif (Tazh-1, Tazh-2, Tazh-3, Tazh-7Bl, and Tazh-7Br) suggests that the in situ ages of some perovskite crystals (Tazh-1, Tazh-7Bl, and Tazh-7Br) are systematically offset from their corresponding ID-TIMS ages. Hence, not all Tazheran perovskite grains are suitable as standards and some previously published work may suffer from unrecognized inaccuracies. Various factors are investigated in an attempt to identify the origin(s) of the matrix effect biasing the in situ measurements. Although there are so far only a limited number of perovskite grains analyzed by all SIMS, LA-ICPMS, and TIMS methods, grains Tazh-1, Tazh-7Bl, and Tazh-7Br all have extremely low FeO, Nb, and LREE contents compared with the other Tazh perovskite and well characterized reference materials (AFK-5 and Ice River), indicating that such chemical variability may cause analytical differences. Furthermore, and perhaps more importantly, the Tazh-1, Tazh-7Bl, and Tazh-7Br perovskite grains are cubic and thus have different crystal structure from most Tazh perovskite and their standards that are orthorhombic. Therefore, crystal structure could be the principal reason for the matrix effect, with secondary matrix effects due to differences in chemical composition, that need to be taken into account in future in situ U-Pb dating of perovskite.

Abstract 2232: Optimizing Performance of Whole Transcriptome RNA-Seq Reference

Abstract Purpose: Whole transcriptome RNA-sequencing (RNA-Seq) has emerged as one of the most effective methods for detection of genomic rearrangements in cancer. Enrichment for poly(A) + RNA as part of library preparation is a standard method to select for mRNAs, but ribosomal RNA depletion and exon capture methods may be preferred for samples of suboptimal RNA quality, such as FFPE. Regardless of the selection and library preparation procedure, RNA-Seq for clinical use requires well characterized reference materials for assay quality control and fusion detection verification. However, reference materials developed for targeted NGS panels performed sub-optimally on RNA-Seq. This study was undertaken to design, optimize and improve RNA-Seq performance with a novel transcriptome-scale RNA Fusion reference material. Procedure: Seraseq® Fusion RNA Mix is highly multiplexed with 18 clinically relevant fusion RNAs and is designed for targeted NGS panels. The biosynthetic fusions are targeted to 60 copies per nanogram of total RNA from GM24385 human reference cell line and contain poly-A tail of ~37 templated A's. We tested whether increasing the length of the poly-A tail would improve the efficiency of binding to an oligo dT column and improve performance in total RNA-Seq NGS assays that use poly(A) + selection. E. coli Poly(A) Polymerase was used to extend tails, and efficiency of RNA recovery from oligo-dT columns was assessed visually by gel analysis. The fusion RNAs (with standard or lengthened poly-A tails) were mixed with total RNA from GM24385 human reference cell line. Since GM24385 is a lymphoid cell line, highly abundant immune transcripts may reduce the prevalence of the fusion RNAs in the selected RNAs. Therefore, mixtures were made at the normal concentration (~60 copies/ng, or 1X) as well as at 3-fold and 10-fold concentrations. Fusion detection was performed using Illumina TruSeq Stranded mRNA(polyA) kit and Illumina HiSeq, run in 2 × 150bp mode. Results: The proportional recovery was improved with the longer (>100 A's) tail length. This translated to improvement in NGS detection with longer poly-A tail length giving from 10% to 50% more fusion reads. Increasing the Fusion RNA concentration led to a proportion increase in fusion reads per million total reads. The increase from <1 fusion reads/million total reads to >5 fusion reads/million resulted in more robust and consistent fusion detection. Conclusions: These studies indicate that reference materials similar to the Seraseq Fusion RNA mix reference material, but with greater concentration of Fusion RNAs (3 - 10 fold higher concentration) and with longer polyA tail length will be applicable quality control materials for whole transcriptome RNA-Seq NGS assays. These novel reference materials may aid clinical labs in developing sensitive new RNA-Seq Fusion detection assays and tuning their bioinformatics pipeline to more precise selection of therapeutic strategies for patients. Citation Format: Catherine Huang, Matthew G. Butler, Yves Konigshofer, Jessica Dickens, Rajeswari Vemula, Omoshile Clement, Bharathi Anekella. Optimizing Performance of Whole Transcriptome RNA-Seq Reference [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2232.

Novel Approaches to Develop Critical Reference Materials for Noninvasive Prenatal Testing: A Pilot Study.

Highly characterized reference materials are required to expand noninvasive prenatal testing (NIPT) for low incidence aneuploidies and microdeletions. The goal of this study was to develop reference materials for the development of next generation circulating cell-free DNA (ccfDNA) assays. This was a prospective study of pregnancies complicated by positive prenatal genetic screening. ccfDNA was isolated from maternal plasma and amplified. Lymphoblastoid cell lines were prepared from maternal peripheral blood mononuclear cells and fetal cord blood cells. Cells were Epstein-Barr virus immortalized and expanded. Amplified DNA and to a limited extent formulated lymphoblastoid-derived ccfDNA was tested in SNP-based and chromosome counting (CC) based massively parallel sequencing assays. Enrolled cases included fetuses with: T21 (2), T18 (1), T18-XXX (1), XYY (1), microdeletions (1), and euploid (2). Three lymphoblastoid cells lines were prepared. Genomic DNA was extracted from cell lines and fragmented to simulate ccfDNA. ccfDNA isolation yielded about 2000 usable genome equivalents of DNA for each case for amplification. Although the sonicated genomic DNA derived from lymphoblastoid cell lines did not yield results compatible with NIPT assays, when blinded, NIPT platforms correctly identified the amplified ccfDNA isolated from blood in the majority of cases. This study showed that maternal blood samples from pregnancies complicated by common chromosomal abnormalities can be used to generate materials for the development and evaluation of NIPT assays.

Characterization of Reference Materials for Spinal Muscular Atrophy Genetic Testing: A Genetic Testing Reference Materials Coordination Program Collaborative Project

Spinal muscular atrophy (SMA) is an autosomal recessive disorder predominately caused by bi-allelic loss of the SMN1 gene. Increased copies of SMN2, a low functioning nearly identical paralog, are associated with a less severe phenotype. SMA was recently recommended for inclusion in newborn screening. Clinical laboratories must accurately measure SMN1 and SMN2 copy number to identify SMA patients and carriers, and to identify individuals likely to benefit from therapeutic interventions. Having publicly available and appropriately characterized reference materials with various combinations of SMN1 and SMN2 copy number variants is critical to assure accurate SMA clinical testing. To address this need, the CDC-based Genetic Testing Reference Materials Coordination Program, in collaboration with members of the genetic testing community and the Coriell Institute for Medical Research, has characterized 15 SMA reference materials derived from publicly available cell lines. DNA samples were distributed to four volunteer testing laboratories for genotyping using three different methods. The characterized samples had zero to four copies of SMN1 and zero to five copies SMN2. The samples also contained clinically important allele combinations (eg, zero copies SMN1, three copies SMN2), and several had markers indicative of an SMA carrier. These and other reference materials characterized by the Genetic Testing Reference Materials Coordination Program are available from the Coriell Institute and are proposed to support the quality of clinical laboratory testing.

SI-traceable monoelemental solutions on the highest level of accuracy: 25 years from the foundation of CCQM to recent advances in the development of measurement methods**The authors would like to dedicate this article to Dr Mike Sargent who led the Working Group on Inorganic Analysis for two decades. His wise and diplomatic leadership was important for the direction the IAWG took

Within the Working Group on Inorganic Analysis (IAWG) of the Consultative Committee for Amount of Substance: Metrology in Chemistry and Biology (CCQM) international key comparisons and pilot studies related to inorganic analysis are carried to ensure consistency in this field at the highest level. Some of these comparisons deal directly with the preparation and characterization of monoelemental solutions or with topics, closely related. The importance of monoelemental solutions lies in the fact that almost every measurement in inorganic analysis relies on the comparison with either a reference material, or references in form of solutions, usually (mono)elemental solutions. All quantitative measurement approaches, e.g. isotope dilution or standard addition, need an accurate reference solution made from a well characterized reference material, prepared under full gravimetric control. These primary (monoelemental) solutions do not only serve as arbitrary references/calibration solutions, but they also link up measurement results to the International System of units (SI), this way establishing the so-called metrological traceability to a measurement unit of the SI. Without such solutions on the highest possible level of accuracy and with the smallest possible associated uncertainties (for e.g. element content and/or impurities), an analysis itself can never be as good as it could be with appropriate reference solutions. This article highlights select key comparisons and pilot studies dealing with monoelemental solution-related topics within the IAWG from the foundation of CCQM—25 years ago—up to latest achievements in the field of inorganic analysis.

Characterization and Relative Quantitation of Wheat, Rye, and Barley Gluten Protein Types by Liquid Chromatography-Tandem Mass Spectrometry.

The consumption of wheat, rye, and barley may cause adverse reactions to wheat such as celiac disease, non-celiac gluten/wheat sensitivity, or wheat allergy. The storage proteins (gluten) are known as major triggers, but also other functional protein groups such as α-amylase/trypsin-inhibitors or enzymes are possibly harmful for people suffering of adverse reactions to wheat. Gluten is widely used as a collective term for the complex protein mixture of wheat, rye or barley and can be subdivided into the following gluten protein types (GPTs): α-gliadins, γ-gliadins, ω5-gliadins, ω1,2-gliadins, high- and low-molecular-weight glutenin subunits of wheat, ω-secalins, high-molecular-weight secalins, γ-75k-secalins and γ-40k-secalins of rye, and C-hordeins, γ-hordeins, B-hordeins, and D-hordeins of barley. GPTs isolated from the flours are useful as reference materials for clinical studies, diagnostics or in food analyses and to elucidate disease mechanisms. A combined strategy of protein separation according to solubility followed by preparative reversed-phase high-performance liquid chromatography was employed to purify the GPTs according to hydrophobicity. Due to the heterogeneity of gluten proteins and their partly polymeric nature, it is a challenge to obtain highly purified GPTs with only one protein group. Therefore, it is essential to characterize and identify the proteins and their proportions in each GPT. In this study, the complexity of gluten from wheat, rye, and barley was demonstrated by identification of the individual proteins employing an undirected proteomics strategy involving liquid chromatography–tandem mass spectrometry of tryptic and chymotryptic hydrolysates of the GPTs. Different protein groups were obtained and the relative composition of the GPTs was revealed. Multiple reaction monitoring liquid chromatography–tandem mass spectrometry was used for the relative quantitation of the most abundant gluten proteins. These analyses also allowed the identification of known wheat allergens and celiac disease-active peptides. Combined with functional assays, these findings may shed light on the mechanisms of gluten/wheat-related disorders and may be useful to characterize reference materials for analytical or diagnostic assays more precisely.

Assessment of Five Monazite Reference Materials for U-Th/Pb Dating Using Laser-Ablation ICP-MS

Monazite is a common accessory phosphate mineral that occurs under a wide range of pressure and temperature conditions in sedimentary, metamorphic and igneous rocks. Monazite contains high amounts of Th and U, rendering single monazite grains suitable for in-situ U-Th/Pb dating using laser ablation inductively-coupled mass spectrometry (LA-ICP-MS). Two key aspects of monazite dating that are critical for accurate age data with maximum precision are (i) optimized instrumental conditions to minimize analytical scatter and (ii) a well characterized reference material to ensure the accuracy of the obtained aged. Here, we analyzed five monazite reference materials (USGS 44069, 94-222, MAdel, Moacir and Thompson Mine Monazite) for their U-Th/Pb ages using LA-ICP-MS technique and applied a variety of laser spot diameters and repetition rates to find the best operational conditions to achieve accurate age data while maintaining maximum precision. We find that a spot diameter of 10 µm and a repetition rate of 10 Hz yield the most precise ages with a deviation of ±2.0% from their respective high-precision U/Pb literature age data. Ages were reproduced in three different LA-ICP-MS laboratories using these parameters. Each reference material was tested for its suitability as a matrix-matched age reference material. For this, a rotating, iterative approach was adopted in which one reference monazite was used as calibration reference material against all others, which were treated as unknowns. The results reveal that USGS 44069, 94-222, Thompson Mine Monazite and MAdel all agree with their respective calculated ages and ID-TIMS reference ages and thus are suggested as suitable calibration reference materials. Moacir, however, appears slightly older than previously suggested (up to 4%), thus, caution is advised here when using Moacir as reference material for U-Th/Pb LA-ICP-MS dating in the absence of further absolute age calibration.

Abstract 1627: Custom VariantFlex technology allows rapid design and testing of reference materials for tumor genotyping assays

Abstract Introduction: Development and validation of tumor genotyping assays requires highly characterized reference materials for effective assessment of accuracy, precision, reproducibility and limits of detection. Highly multiplexed reference materials can facilitate and expedite these studies; however, there is not a single reference material that is appropriate for all assays. Traditional cancer cell line methods or genetic engineering methods can take 6 - 9 months, so more flexible solutions for reference materials are needed. Here we describe the development of VariantFlex technology, which enables a laboratory to configure a reference material to contain the variants of interest at the allele frequency of relevance to their studies in rapid time. Methods: A library of biosynthetic constructs was generated that contains ~140 somatic cancer DNA variants (SNVs, small and large indels and tandem duplications), ~27 RNA fusions, and 6 very large gene region constructs for copy number gains. TaqMan® digital PCR assays were developed to precisely quantify the variant allele fraction, fusion RNA concentration or copy number gain. As an example, biosynthetic constructs bearing multiple SNVs in TP53, PIK3CA and EGFR, large deletions in EGFR, and the structural variants NCOA4-RET and TPR-ALK, were selected from the VariantFlex library and spiked into DNA extracted from the highly characterized GM24385 cell line. The mixture was processed to obtain ctDNA-like profile, encapsulated to provide stability, and then diluted in artificial plasma to generate a customized reference material for liquid biopsy. Results: The ctDNA reference material was quantified by digital PCR and performance was verified on hybrid capture and amplicon based NGS assays. Variant allele frequency as low as 0.125% VAF was accurately targeted (range for 0.125% target was +/- 0.025% by digital PCR). The VariantFlex technology has been validated to work with amplified NGS workflows, hybrid-capture based NGS assays as well as non-NGS assays such as qPCR and array based methods. Conclusions: This study shows how a large library of cancer-related variants can facilitate rapid production of customized reference materials. The flexibility to include exactly the variants of interest, at the critical allele frequencies, and in the most patient-like format will facilitate assay development and validation. Citation Format: Catherine Huang, Ram Santhanam, Dan Brudzewsky, Trevor Brown, Russell Garlick, Bharathi Anekella. Custom VariantFlex technology allows rapid design and testing of reference materials for tumor genotyping assays [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1627.

Refractive index retrieval in the UV range using white light spectral interferometry

Continuous refractive index measurement in the UV spectral region and a small part of the Vis region (up to 520 nm) is performed by using white light spectral interferometry. The main limitations of operating in this region are the high dispersion and high absorption. The problems derived from high dispersion are overcome taking the data in several shots, that is, recording several interferograms that must be partially overlapped. Whereas, high absorbers require the use of thinner samples, while still keeping a precise measurement of the sample width. We show the capacity of the technique with well characterized reference materials such as BK7, quartz and deionised water.

Overcoming challenges in single particle inductively coupled plasma mass spectrometry measurement of silver nanoparticles.

Single particle ICP-MS has evolved rapidly as a quantitative method for determining nanoparticle size and number concentration at environmentally relevant exposure levels. Central to the application of spICP-MS is a commonly used, but not rigorously validated, calibration approach based on the measured transport efficiency and the response of ionic standards. In this work, we present a comprehensive and systematic study of the accuracy, precision and robustness of spICP-MS using the rigorously characterized reference material (RM) 8017 (Polyvinylpyrrolidone Coated Nominal 75nm Silver Nanoparticles), recently issued by the National Institute of Standards and Technology (NIST). We report for the first time, statistically significant differences in frequency-based and size-based measures of transport efficiency with NIST RM 8013 Gold Nanoparticles and demonstrate that the size-based measure of transport efficiency is more robust and yields accurate results for the silver nanoparticle RM relative to TEM-based reference values. This finding is significant, because the frequency-based method is more widely applied. Furthermore, we demonstrate that the use of acidified ionic standards improves measurement of ICP-MS Ag response, but does not degrade the accuracy of the results for AgNP suspensions in water or various other diluents. Approaches for controlling AgNP dissolution were investigated and are shown to effectively improve particle stability in dilute suspensions required for spICP-MS analysis, while minimally affecting the measured intensity and allowing for more robust analysis. This study is an important and necessary advancement toward full validation and adoption of spICP-MS by the broader research community. Graphical abstract Measurement challenges in spICP-MS analysis.

Compound-Specific Chlorine Isotope Analysis of Tetrachloromethane and Trichloromethane by Gas Chromatography-Isotope Ratio Mass Spectrometry vs Gas Chromatography-Quadrupole Mass Spectrometry: Method Development and Evaluation of Precision and Trueness.

Compound-specific chlorine isotope analysis of tetrachloromethane (CCl4) and trichloromethane (CHCl3) was explored by both, gas chromatography-isotope ratio mass spectrometry (GC-IRMS) and GC-quadrupole MS (GC-qMS), where GC-qMS was validated in an interlaboratory comparison between Munich and Neuchâtel with the same type of commercial GC-qMS instrument. GC-IRMS measurements analyzed CCl isotopologue ions, whereas GC-qMS analyzed the isotopologue ions CCl3, CCl2, CCl (of CCl4) and CHCl3, CHCl2, CHCl (of CHCl3), respectively. Lowest amount dependence (good linearity) was obtained (i) in H-containing fragment ions where interference of 35Cl- to 37Cl-containing ions was avoided; (ii) with tuning parameters favoring one predominant rather than multiple fragment ions in the mass spectra. Optimized GC-qMS parameters (dwell time 70 ms, 2 most abundant ions) resulted in standard deviations of 0.2‰ (CHCl3) and 0.4‰ (CCl4), which are only about twice as large as 0.1‰ and 0.2‰ for GC-IRMS. To compare also the trueness of both methods and laboratories, samples from CCl4 and CHCl3 degradation experiments were analyzed and calibrated against isotopically different reference standards for both CCl4 and CHCl3 (two of each). Excellent agreement confirms that true results can be obtained by both methods provided that a consistent set of isotopically characterized reference materials is used.

Development and Characterization of Reference Materials for Genetic Testing: Focus on Public Partnerships.

Characterized reference materials (RMs) are needed for clinical laboratory test development and validation, quality control procedures, and proficiency testing to assure their quality. In this article, we review the development and characterization of RMs for clinical molecular genetic tests. We describe various types of RMs and how to access and utilize them, especially focusing on the Genetic Testing Reference Materials Coordination Program (Get-RM) and the Genome in a Bottle (GIAB) Consortium. This review also reinforces the need for collaborative efforts in the clinical genetic testing community to develop additional RMs.

Experimental findings on the underwater measurements uncertainty of speed of sound and the alignment system

Speed of sound is an important quantity to characterize reference materials for ultrasonic applications, for instance. The alignment between the transducer and the test body is an key activity in order to perform reliable and consistent measurement. The aim of this work is to evaluate the influence of the alignment system to the expanded uncertainty of such measurement. A stainless steel cylinder was previously calibrated on an out of water system typically used for calibration of non-destructive blocks. Afterwards, the cylinder was calibrated underwater with two distinct alignment system: fixed and mobile. The values were statistically compared to the out-of-water measurement, considered the golden standard for such application. For both alignment systems, the normalized error was less than 0.8, leading to conclude that the both measurement system (under and out-of-water) do not diverge significantly. The gold standard uncertainty was 2.7 m-s-1, whilst the fixed underwater system resulted in 13 m-s-1, and the mobile alignment system achieved 6.6 m-s-1. After the validation of the underwater system for speed of sound measurement, it will be applied to certify Encapsulated Tissue Mimicking Material as a reference material for biotechnology application.

Comprehensive Pb‐Sr‐Nd‐Hf isotopic, trace element, and mineralogical characterization of mafic to ultramafic rock reference materials

AbstractControlling the accuracy and precision of geochemical analyses requires the use of characterized reference materials with matrices similar to those of the unknown samples being analyzed. We report a comprehensive Pb‐Sr‐Nd‐Hf isotopic and trace element concentration data set, combined with quantitative phase analysis by XRD Rietveld refinement, for a wide range of mafic to ultramafic rock reference materials analyzed at the Pacific Centre for Isotopic and Geochemical Research, University of British Columbia. The samples include a pyroxenite (NIM‐P), five basalts (BHVO‐2, BIR‐1a, JB‐3, BE‐N, GSR‐3), a diabase (W‐2), a dolerite (DNC‐1), a norite (NIM‐N), and an anorthosite (AN‐G); results from a leucogabbro (Stillwater) are also reported. Individual isotopic ratios determined by MC‐ICP‐MS and TIMS, and multielement analyses by HR‐ICP‐MS are reported with 4–12 complete analytical duplicates for each sample. The basaltic reference materials have coherent Sr and Nd isotopic ratios with external precision below 50 ppm (2SD) and below 100 ppm for Hf isotopes (except BIR‐1a). For Pb isotopic reproducibility, several of the basalts (JB‐3, BHVO‐2) require acid leaching prior to dissolution. The plutonic reference materials also have coherent Sr and Nd isotopic ratios (<50 ppm), however, obtaining good reproducibility for Pb and Hf isotopic ratios is more challenging for NIM‐P, NIM‐N, and AN‐G due to a variety of factors, including postcrystallization Pb mobility and the presence of accessory zircon. Collectively, these results form a comprehensive new database that can be used by the geochemical community for evaluating the radiogenic isotope and trace element compositions of volcanic and plutonic mafic‐ultramafic rocks.

Evaluation of New Geological Reference Materials for Uranium-Series Measurements: Chinese Geological Standard Glasses (CGSG) and Macusanite Obsidian

Recent advances in high-resolution, rapid, in situ microanalytical techniques present numerous opportunities for the analytical community, provided accurately characterized reference materials are available. Here, we present multicollector thermal ionization mass spectrometry (MC-TIMS) and multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS) uranium and thorium concentration and isotopic data obtained by isotope dilution for a suite of newly available Chinese Geological Standard Glasses (CGSG) designed for microanalysis. These glasses exhibit a range of compositions including basalt, syenite, andesite, and a soil. Uranium concentrations for these glasses range from ∼2 to 14 μg g(-1), Th/U weight ratios range from ∼4 to 6, (234)U/(238)U activity ratios range from 0.93 to 1.02, and (230)Th/(238)U activity ratios range from 0.98 to 1.12. Uranium and thorium concentration and isotopic data are also presented for a rhyolitic obsidian from Macusani, SE Peru (macusanite). This glass can also be used as a rhyolitic reference material, has a very low Th/U weight ratio (around 0.077), and is approximately in (238)U-(234)U-(230)Th secular equilibrium. The U-Th concentration data agree with but are significantly more precise than those previously measured. U-Th concentration and isotopic data agree within estimated errors for the two measurement techniques, providing validation of the two methods. The large (238)U-(234)U-(230)Th disequilibria for some of the glasses, along with the wide range in their chemical compositions and Th/U ratios should provide useful reference points for the U-series analytical community.