Reference Materials For Quality Assurance Research Articles

Customizing New Titanium Dioxide Nanoparticles with Controlled Particle Size and Shape Distribution: A Feasibility Study Toward Reference Materials for Quality Assurance of Nonspherical Nanoparticle Characterization

An overview is given on the synthesis of TiO2 nanoparticles with well‐defined nonspherical shapes (platelet like, bipyramidal, and elongated), with the focus on controlled, reproducible synthesis, as a key requirement for the production of reference materials with homogeneous and stable properties. Particularly with regard to the nanoparticle shapes, there is a high need of certified materials, solely one material of this type being commercially available since a few months (elongated TiO2). Further, measurement approaches with electron microscopy as the golden method to tackle the nanoparticle shape are developed to determine accurately the size and shape distribution for such nonspherical particles. A prerequisite for accurate and easy (i.e., automated) image analysis is the sample preparation, which ideally must ensure a deposition of the nanoparticles from liquid suspension onto a substrate such that the particles do not overlap, are solvent‐free, and have a high deposition density. Challenges in the synthesis of perfectly monodispersed and solvent‐free TiO2 nanoparticles of platelet and acicular shapes are highlighted as well as successful measurement approaches on how to extract from 2D projection electron micrographs the most accurate spatial information, that is, true 3D size, for example, of the bipyramidal nanoparticles with different geometrical orientations on a substrate.

Role of Bharatiya Nirdeshak Dravya (BND®) in Development of Indian Reference Materials for Quality Assurance of Products

The benchmark of life and quality infrastructure of a nation is mainly dependent on the measurement system of country. The growth of nation in addition to its science & technology is highly influenced by measurement of any physical quantities or policies. The ancient as well as modern sciences predominantly rely on the measurement procedure and its accuracy. One can say that science starts from measurements hence it can be considered as one of the basic aspect of science and its growth. To perform these measurements which are basis of life, simple to sophisticated equipment's are used. The results from these instruments may be not accurate and precise if it is not calibrated. With calibration there is need of comparable measurement to attain the unbroken chain of measurements. Now Certified Reference Materials (CRMs) played critical role in calibration of instrument and to get the comparable measurements which are traceable to national or world-wide standards. The outcomes of sophisticated instruments may be wrong without its calibration. So now it is the time for the scientific and new innovations world to calibrate the sophisticated instruments using these certified reference standards. These CRMs are generally produced and maintained by "National Measurement Institute (NMI)" of the country. In India, Bharatiya Nirdeshak Dravya (BND®) division of National Physical Laboratory (NPL) is continuously working in developing the Indian Reference Materials (IRMs). Now these IRMs can be defined as those substances which are key factors for maintaining a healthy measurement system and to get very precise value. With this these are cost effective IRMs which will improve the quality of products and will help in economic growth of the country. In this article, we are discussing about that measurements which are attached to each steps of our life. But it is necessary that measurement should be accurate and precise and traceable to some true value. CSIR-NPL is continuously focused on the development of IRMs for calibration of instrument, improvement in quality of life, industrial production, global trade and to get accurate and precise measurements.

Reference materials for quality assurance of environmental plutonium analysis

Reference materials (RMs) are very important for method development and validation. In order to quickly and reliably select the suitable RM for validating the determination of plutonium (Pu), we reviewed the RMs of Pu and prepared extensive Pu datasets in this study. After data treatment and a series of statistical analyses, we obtained the statistical values of 238−241Pu activity and Pu isotopic ratio for RMs. The statistical value of 239+240Pu activity is consistent with the certified value, indicating these measured values are highly reliable. We anticipate that, after further independent work at different laboratories, the statistical values of the Pu isotopic ratios are very important to validate analysis methods and calibrate the mass bias for environmental Pu analysis.

Multilaboratory Assessment of a New Reference Material for Quality Assurance of Cell-Free Tumor DNA Measurements

We conducted a multilaboratory assessment to determine the suitability of a new commercially available reference material with 40 cancer variants in a background of wild-type DNA at four different variant allele frequencies (VAFs): 2%, 0.50%, 0.125%, and 0%. The variants include single nucleotides, insertions, deletions, and two structural variations selected for their clinical importance and to challenge the performance of next-generation sequencing (NGS) methods. Fragmented DNA was formulated to simulate the size distribution of circulating wild-type and tumor DNA in a synthetic plasma matrix. DNA was extracted from these samples and characterized with different methods and multiple laboratories. The various extraction methods had differences in yield, perhaps because of differences in chemistry. Digital PCR assays were used to measure VAFs to compare results from different NGS methods. Comparable VAFs were observed across the different NGS methods. This multilaboratory assessment demonstrates that the new reference material is an appropriate tool to determine the analytical parameters of different measurement methods and to ensure their quality assurance.

Preparation of matrix reference material for quality assurance and control of pesticides analysis in olive oil

The legislative requirements and the concern about the harmful effects of pesticide residues have encouraged National Institute of Standards to start development of a series of reference materials for food control to meet requirements of the regulatory authorities, improvement of the comparability and the quality of pesticides analysis and monitoring laboratories overall performance on a reliable, systematic and comparable basis. CRMs play a key role in quality control, precision studies, confirmation and validation of test methods. Comparability and the accuracy of the measurement results depend mainly on availability of certified reference materials appropriate for a particular application. This article gives an overview for complete production process of olive oil matrix reference material certified for organochlorine pesticides. A commercially available virgin olive oil was spiked with 23 pesticides in the range of 4 ng/g, and batch of 300 units was prepared. Characterization, stability, within- and between-samples homogeneity were determined according to ISO standards and guides. The results show that matrix reference material prepared under controlled metrologically valid procedures is valuable tool in the food analysis.

Abstract 3657: Multi-laboratory assessment of a new reference material for quality assurance of circulating tumor DNA measurements

Abstract The accurate diagnosis and monitoring of cancer, using circulating tumor DNA (ctDNA), is a major challenge, given the low concentration and complexity of the target molecules. Suitable reference materials are required for clinical laboratories to achieve the high levels of measurement assurance and reproducibility. The methods and instruments for ctDNA assays are rapidly evolving to improve the sensitivity and specificity, resulting in a challenge to compare these different assays for the measurement of the diverse classes of ctDNA cancer biomarkers. To address this goal, a new reference material was developed consisting of 40 cancer mutations in a background of wild-type DNA at six different allele fractions (2%, 1%, 0.5%, 0.25%, 0.125, and 0 %). The cancer mutations include single nucleotide variants, insertions, deletions, and two structural variations that were selected for their clinical importance and challenges for next generation sequencing (NGS) methods. The reference material is formulated in a synthetic plasma matrix at a concentration of 25 ng/mL, levels that are consistent with patient samples. The DNA has been processed to accurately simulate the size of patient ctDNA, resulting in a similar conversion rate of the DNA for next generation sequencing methods. The samples were sent to five different laboratories involved in ctDNA measurements. Digital PCR assays for the variants were developed to confirm the allele fractions by several laboratories. When absorbance, fluorescent dye binding, and PCR methods were used to quantify the extracted ctDNA reference material, the results were significantly different, indicating the need for standard methods and reference materials to ensure reproducible results of this critical step. Different NGS methods (including targeted amplicons, hybrid selection, and SiMSen-seq) and instruments were used by the labs to analyze the refence materials at the different allele fractions. The results showed that the assays had significant differences in the ability to detect classes of variants at different concentrations. This new reference material was shown to be useful to benchmark the sensitivity and selectivity of different NGS methods and bioinformatic pipelines. This multi-laboratory assessment clearly demonstrates that the new reference material is highly valuable tool to ensure the reproducibility of ctDNA measurements including the sample extraction, analytical, and bioinformatic steps. Citation Format: Erica Stein, Hua-Jun He, Kenneth D. Cole, Russell K. Garlick, Yves Konigshofer, Tony E. Godfrey, Michael G. Goggins, Michael Borges, Margaret Gulley, Mickey Williams, Chris Karlovich, Corinne Camalier, Lynn Sorbara, Matthew R. Young, Sudhir Srivastava. Multi-laboratory assessment of a new reference material for quality assurance of circulating tumor DNA measurements [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 3657.

Development of a multi-VOC reference material for quality assurance in materials emission testing.

Emission test chamber measurement is necessary to proof building materials as sources of volatile organic compounds (VOCs). The results of such measurements are used to evaluate materials and label them according to their potential to emit harmful substances, polluting indoor air. If only labelled materials were installed indoors, this would improve indoor air quality and prevent negative impacts on human health. Because of the complex testing procedure, reference materials for the quality assurance are mandatory. Currently, there is a lack of such materials because most building products show a broad variation of emissions even within one batch. A previous study indicates lacquers, mixed with volatile organic pollutants, as reproducible emission source for a wide range of substances. In the present study, the curing of the lacquer-VOC mixture inside micro-chambers was optimised. Therefore, the humidity and the chamber flow were varied. Typical indoor air pollutants with a wide range of volatilities, for example, styrene, n-hexadecane, dimethyl and dibutyl phthalate were selected. It turned out that, under optimised curing parameters inside the micro-chamber, their emission can be reproduced with variations of less than 10%. With this, a next important step towards a reference material for emission testing was achieved.

Development of certified matrix reference materials for quality assurance of screening 134Cs and 137Cs in food

A certified reference material using activated alumina powder certified for activity of 134Cs and 137Cs was developed. The results of the verification and the certification are described. The certified reference material can be used for quality assurance of screening activity measurements of 134Cs and 137Cs in food/foodstuffs. Commercially available equipments were experimentally tested using the CRM and another CRM including 40K. The results of these tests are also shown.

Basic Research on Developing Scallop Tissue Reference Material for Quality Assurance of Diarrhetic Shellfish Poisoning (DSP) Mouse Bioassay (MBA):-Free Fatty Acid (FFA) in Homogenized Frozen Scallop Slurry and its Effect on MBA-

Diarrhetic shellfish poisoning (DSP) is one of the gastrointestinal illness caused by the consumption of shellfish contaminated with toxigenic dinoflagellates. The main toxins responsible for DSP are Okadaic acid (OA) and its derivatives. Remarkable increase of free fatty acid (FFA) in the hepatopancreas (HP) of scallops during storage in a freezer is occasionally observed and it results in pseudo-positive with the MBA for DSP. In the process of making reference material(RM) for MBA, which is consisted of a set of a vial containing a piece of filter infused with OA and DSP negative slurry of homogenized scallop whole meat (WH), we investigated the concentration of FFA. The determination of OA and FFA concentrations was performed using liquid chromatography with a fluorometric detector for anthryl diazomethane (ADAM) derivatives. In this study FFA composition and toxicity were surveyed in homogenized scallop tissue stored in a freezer at -70°C for 4 months. Most of the samples were nontoxic as determined by mouse bioassay and showed low FFA concentration; one sample showed both toxic and high FFA concentrations. These results suggest that the determination of FFA concentration in scallop tissue by HPLC coupled with the MBA for DSP is important for RM.

Basic Research on Developing Scallop Tissue Reference Material for Quality Assurance of Diarrhetic Shellfish Poisoning (DSP) Mouse Bioassay-Stability of Okadaic Acid (OA)-

The preparation of the reference material (RM) for mouse bioassay (MBA) of diarrheic shellfish poisoning (DSP) toxin was attempted. To obtain basic data on the RM, the stability of okadaic acid (OA), which causes DSP, and the method of spiking scallop tissue with OA were examined. Microwave, ultrasonic wave, and UV, which are conventionally used in experiments or may exist in environment, did not affect on the recovery of OA. The recovery rate of OA from thermo treatment at 50-200 °C was examined periodically. Results suggest that temperature has no effect on the recovery rate of OA at temperatures used during conventional analysis and transportation. However, a rapid decrease in recovery was observed during heating at more than 120 °C. In addition, the half-life of OA heated in the range of 120-130 °C was 1 h. OA in acetone solution that was stored in brown vials or dried at the bottom of brown vials was stable during freezing( -35 °C), refrigeration, and storage at room temperature (20 °C) for six months. The titer of OA tested by MBA was stable in stocked samples, but the recovery rate of OA decreased by about 10 % at the HPLC level after 15 months of storage. It was clarified that the recovery rate of OA absorbed in filter paper decreased gradually but the recovery rate of OA was stable under conditions of three-week refrigeration. Samples were distributed to collaborating laboratories and their results of MBA were compared and we did not find any problems on the quality of RM or on the results of MBA quality assurance.

Selenium status of South Bohemia seniors characterized by INAA of blood serum

To estimate the status of selenium in seniors of the South Bohemia region, Czech Republic, 481 serum samples from seniors living in 17 Asylum Houses for seniors in the age between 60 and 99 years were obtained. Samples were analyzed by instrumental neutron activation analysis with concurrent analysis of 4 reference materials for quality assurance. Average concentration of serum Se, arithmetic means in individual Asylum Houses, frequency distribution of serum Se concentrations as well as five years running monitoring of serum Se concentrations of one group of seniors proved selenium deficiency of the elderly population of the region South Bohemia.

Current radioactivity content of wild edible mushrooms: A candidate for an environmental reference material

The paper presents the results of radiological investigation of several mushroom samples collected in the fall of 2004 in different parts of Europe. The work was performed in order to support decision making to develop and produce a certified reference material for quality assurance of radionuclide measurements in environmental samples. The levels of 137Cs in mushrooms varied widely ranging from 0.6 to 4300 Bq/kg on dry mass basis, while those of natural 40K were relatively constant. In one sample 60Co of unknown origin was detected (25±2 Bq/kg dry mass), while 90Sr concentrations were usually below the detection limit (<150 mBq/kg dry mass).

Application of Isotope Dilution Gas Chromatography−Mass Spectrometry in Analysis of Organochlorine Pesticide Residues in Ginseng Root

A highly accurate and precise method based on isotope dilution gas chromatography-mass spectrometry was developed for the determination of five matrix-bound organochlorine pesticides, namely, hexachlorobenzene and hexachlorocyclohexanes (alpha-, beta-, delta-, and gamma- isomers), in a reference sample of Panax gingseng. Identification of the analytes was confirmed under selective ion monitoring mode by the presence of two dominant ion fragments within the specific time windows (+/-1% of the relative retention time with respect to the calibration standards) and matching of relative ion intensities of the concerned ions in samples and calibration standards (within +/-5%). Quantification was based on the measurement of concentration ratios of the natural and isotopic analogues in the sample and calibration blends. To circumvent the tedious iterative process of exact isotope matching that is often used in isotope dilution mass spectrometry analysis, a single-point calibration procedure was adopted with the isotopic amount ratios in the sample and calibration blends close to unity (0.9-1.1). Under the described approach, intraday and interday repeatability of replicate analyses of organochlorine pesticides in the ginseng root sample were below 1.4%. The expanded relative uncertainty ranging from 4.0 to 6.5% at a coverage factor of 2 was significantly lower than those of conventional gas chromatographic methods using other calibration techniques (internal or external standards). A deviation of less than 2.0% from the certified values was achieved when applying the developed method to determine hexachlorobenzene, alpha-, and beta-hexachlorocyclohexane in a certified reference material (CRM), BCR-CRM 115. Because of the unavailability of relevant CRMs of herbal origins, the concerned ginseng root sample, after verification of the "true values" of the concerned organochlorine pesticides by the valid primary method, is suitable for serving as an in-house reference material for quality assurance and method validation purposes.

Mineral oil content in sediments and soils: comparability, traceability and a certified reference material for quality assurance

The performance of twelve laboratories with previously established proficiency in the determination of the mineral oil content in a fresh water sediment is described. The summation parameter total petrol hydrocarbon (TPH) is defined according to ISO 16703:2004 with regard to the sample preparation to be applied, the flame ionisation detection (FID) and the boiling range of C10-C40 to be integrated. Comprehensive tests of homogeneity and stability have been carried out on the candidate material using appropriate models. The outcome of the study served as the basis for the certification of the candidate reference material as ERM-CC015a. The certified mass fraction is 1,820+/-130 mg kg(-1) and traceability was established by using an appropriate calibration standard certified for the mass fraction of C10-C40. The interlaboratory scatter of measurement results in this exercise can largely be explained by the variability of the individual calibrations based on this common calibration standard.

Preparation and use of reference materials for quality assurance in inorganic trace analysis

A general preparation and certification scheme used in the Institute of Nuclear Chemistry and Technology (INCT) for the preparation and use of certified reference materials (CRMs) for inorganic trace analysis is presented and contrasted with approaches used by other CRM producers. ‘Definitive’ and ‘very accurate’ methods have a role, based on a combination of neutron activation and quantitative and selective post-irradiation isolation of an indicator radionuclide by column chromatography. Natural matrix CRMs of biological origin including the typical food products are reviewed and the need is identified for new well-characterized materials that would also be suitable for micro-analytical techniques such as PIXE, EDXRF, SS-AAS, etc. There are various approaches to studying homogeneity and its relationship with particle size distribution of a material, and the many problems associated with reliable particle size measurements of CRMs by various techniques are illustrated using real examples. There is an equation relating Ingamells' sampling constant to the mass of single particle of a powder material and this theoretical approach has been compared with experimental results obtained for some CRMs.

Production and Use of BCR Reference Materials for Quality Assurance in Environmental Analysis: An Update

Reference materials represent an invaluable tool for analytical quality control. Certified Reference Materials (CRMs) are used for the validation of methods, whereas various types of (uncertified) Reference Materials (RMs) are used for routine quality control (establishment of control charts) and interlaboratory testing (e.g., proficiency testing). This paper provides background information on the production and use of environmental RMs and describes recent CRMs produced by the BCR (European Commission) for quality assurance in environmental analysis.

IAEA reference materials for quality assurance of marine radioactivity measurements

The IAEA's Marine Environment Laboratory has been assisting laboratories in Analytical Quality Control Services (AQCS) for the analysis of radionuclides in the marine environment since the early seventies. AQCS through world-wide and regional intercomparison exercises and the provision of reference methods and reference materials (RM) have been recognized as an important component of quality assurance/quality control. A total of 43 intercomparison exercises were organized and 37 RM were produced for marine radioactivity studies. All important marine matrices were covered, e.g., seawater, marine sediments of different chemical compositions, fish, shellfish and seaplants. RM were prepared from samples collected at contaminated sites (e.g., the Irish Sea, the Baltic Sea, the Arabian Sea, Mururoa and Bikini Atolls, etc.) as well as from sites affected only by global fallout (e.g., the Pacific Ocean). Available RM are listed in the IAEA biennial catalogue and can be purchased at a minimal price. An overview of prepared RM for radionuclides in marine matrices is presented and discussed in more detail.

Fish otolith reference material for quality assurance of chemical analyses

A certified reference material (CRM) for major, minor and trace element analysis was prepared from sagittal otolith of red emperor ( Lutjanus sebae ) at National Institute for Environmental Studies (NIES), Japan in collaboration with Western Australian Marine Research Laboratories (WAMRL), Australia. Otoliths (1.4 kg) were cleaned, pulverized, sieved to pass a 105-μm screen and homogenized, and 375 vials, each containing 3 g, were prepared. Certified value was determined for Na, Mg, K, Ca, Sr and Ba through a collaboration involving NIES and five other laboratories. The certified value (mean of the means reported from the collaborating laboratories plus or minus the 95% confidence interval) were 97.0±4.2 μmol/g (0.223±0.010%) for Na, 0.88±0.06 μmol/g (21±1 μg/g) for Mg, 7.21±0.20 μmol/g (282±8 μg/g) for K, 9.69±0.11 mmol/g (38.8±0.5%) for Ca, 26.9±0.5 μmol/g (0.236±0.005%) for Sr and 21.1±0.6 nmol/g (2.89±0.09 μg/g) for Ba. Reference values were given for Cu [12 nmol/g (0.74 μg/g)], Zn [7.2 nmol/g (0.47 μg/g)], Cd [0.025 nmol/g (0.0028 μg/g)] and Pb [0.11 nmol/g (0.023 μg/g)] based on definitive analyses at NIES. This CRM will be of practical value for the quality assurance of solution-based elemental analysis of fish otoliths and other marine aragonites .

Role of reference materials in analysis of environmental pollutants

This paper discusses the importance and use of reference materials for quality assurance and quality control in environmental analysis. The general classification of reference materials and categorisation of those for chemical composition are presented. The most common reference materials for pollutants in air, water, waste water, soil, sediments, sludge and some biological materials and their producers are tabulated. Definitions, practical recommendations on selection and handling, and application areas of reference materials are also presented.

Survey of reference materials for trace elements, nuclides and organic microcontaminants

The International Atomic Energy Agency (IAEA), in co-operation with the United Nations Environment Programme (UNEP), has recently prepared a survey on internationally available analytical reference materials for trace elements, nuclides and organic contaminants in biological, environmental and related matrices. The purpose is to help analysts to select reference materials for quality assurance that match as closely as possible, with respect to matrix type and concentrations of the measurands of interest, the “real” samples that are to be measured. The present version of the survey, which is available in the form of two cost-free printed volumes [1], contains over 10,000 certified and information values in 650 reference materials from 27 different producers. The 455 measurands listed include trace elements, major and minor elements, organic contaminants, organometallic compounds, radionuclides and stable isotopes. Currently, the database from which the survey has been produced is being modified and extended so as to make the data available in electronic form via the Internet.