How to use and how not to use certified reference materials in industrial chemical metrology laboratories

2020 ◽  
Vol 35 (2) ◽  
pp. 104-111
Author(s):  
John R. Sieber
Keyword(s):  
Analytical Chemistry ◽  
Reference Materials ◽  
Certified Reference Materials ◽  
International System ◽  
Test Methods ◽  
Standard Reference Materials ◽  
Chemical Metrology ◽  
Laboratory Staff ◽  
Material Development ◽  
System Of Units

As a producer of certified reference materials (CRMs), NIST faces high demand for Standard Reference Materials (SRMs). The demand is exacerbated by widespread misuse of CRMs. When should one use CRMs? When should one not use CRMs? Must labs always use NIST SRMs? How can labs demonstrate analytical capabilities for their accreditation scopes? Why so many questions? Standards developers, laboratory accreditors, and laboratory staff must be able to understand these topics with respect to quality systems in compliance with ISO/IEC 17025. They must calibrate and validate test methods and document traceability to the International System of Units (SI). Many people working in laboratory accreditation and under the umbrella of a quality system do not fully understand what these things are, let alone the language of chemical metrology. On average, they have little training in analytical chemistry, elemental analysis, and reference material development. It is hoped this paper will impress upon the reader the need for understanding how CRMs can be best used in the laboratory. This paper provides a brief background on the above problems and then looks at some of the support and reference information provided by NIST to metals and mining industries labs, commercial CRM producers, and accrediting bodies. The concepts and guidance apply broadly to chemical metrology and fundamental analytical chemistry. The paper includes examples (some from X-ray fluorescence spectrometry) to illustrate concepts.

Metrological Traceability and Roles of Certified Reference Materials

2016 ◽  
Vol 4 (2) ◽  
pp. 81-83
Author(s):  
Akiharu Hioki ◽  
Keyword(s):  
Reference Materials ◽  
Certified Reference Materials ◽  
International System ◽  
Metrological Traceability ◽  
Chemical Analyses ◽  
International Reference ◽  
Calibration And Validation ◽  
Traceability System ◽  
System Of Units ◽  
Metre Convention

Metrological traceability to an international reference, the International System of Units (SI) if possible, is important for the reliability of measurements. The international traceability system under the Metre Convention is briefly introduced. The simplest way to secure metrological traceability in chemical analyses is to utilise certified reference materials (CRMs) for calibration and validation. Finally, as examples of CRMs, NMIJ ones are described.

scholarly journals The importance of cylinder passivation chemistry for preparation and long-term stability of multicomponent monoterpene primary reference materials

2018 ◽  
Author(s):  
Nicholas D. C. Allen ◽  
David R. Worton ◽  
Paul J. Brewer ◽  
Céline Pascale ◽  
Bernhard Niederhauser
Keyword(s):  
Reference Materials ◽  
Chemical Reactivity ◽  
International System ◽  
High Chemical ◽  
Term Stability ◽  
Long Term Stability ◽  
System Of Units ◽  
Primary Reference ◽  
High Chemical Reactivity

Abstract. Monoterpenes play an important role in atmospheric chemistry due to their large anthropogenic and biogenic emission sources and high chemical reactivity. As a consequence, measurements are required to assess how changes in emissions of monoterpenes impact air quality. Accurate and comparable measurements of monoterpenes in indoor and outdoor environments require gaseous primary reference materials (PRMs) that are traceable to the international system of units (SI). PRMs of monoterpenes are challenging to produce due to the high chemical reactivity and low vapour pressures of monoterpenes and also their propensity to convert into other compounds, including other terpenes. In this paper, the long-term stability of gravimetrically prepared static monoterpene PRMs produced in differently passivated cylinders, including sampling canisters, was assessed. We demonstrate that static PRMs of multiple monoterpenes can be prepared and used as a suitable long-term standard. For the first time the effect of cylinder pressure and decanting from one cylinder to another on the chemical composition and amount fraction of monoterpenes was also studied. Gravimetrically prepared PRMs of limonene in high pressure cylinders were compared to a novel portable dynamic reference gas generator based on dilution of pure limonene vapour emitted from a permeation tube.

scholarly journals 230Th-234U model ages of some uranium standard reference materials

2011 ◽  
Vol 1 (1) ◽  
pp. 31-35 ◽  
Author(s):  
R. W. Williams ◽  
A. M. Gaffney
Keyword(s):  
Reference Materials ◽  
Closed System ◽  
Half Life ◽  
Certified Reference Materials ◽  
Isotope Dilution Mass Spectrometry ◽  
Standard Reference Materials ◽  
National Bureau ◽  
System Behavior ◽  
Icp Ms ◽  
Solid Form

Abstract The “age” of a sample of uranium is an important aspect of a nuclear forensic investigation and of the attribution of the material to a source. The 230Th- 234U chronometer can be used to determine the production date of even very recently-produced material ( 234U half life = 245250 ± 490 years; 230Th half life = 75690 ± 230 years [1]), provided that the 230Th/234U at the time of formation is known, and that there has been no Th-U fractionation in the sample since production. For most samples of uranium, ages determined with this chronometer are “model ages”, because they are based on the assumptions of a) some initial amount of 230Th in the sample, and b) closed-system behavior of the sample since production. The uranium standard reference materials originally prepared and distributed by the former US National Bureau of Standards and now distributed by New Brunswick Laboratory as certified reference materials (NBS SRM = NBL CRM) are good candidates for materials where these assumptions may be tested. The U isotopic standards have known purification and production dates and closed-system behavior in the solid form (U3O8) may be reliably assumed. In addition, these materials are widely available and can serve as informal round-robin inter-laboratory comparison samples. We determined 230Th-234U model ages for seven of these isotopic standards by isotope dilution mass spectrometry using a multi-collector ICP-MS. The standards dated for this study are U005-A, U010, U030-A, U100, U850, U900 and U970. Model ages obtained range from ∼ 30 to ∼ 52 years ago (reference date: 5-May-2009). The model age of U100 is the same as the purification date, within uncertainty. The other six standards analyzed all give model ages older than the purification dates of record. The magnitude of the discrepancy between model age and purification date does not correlate with the model age or the amount of 232Th in the samples. This indicates that excess 230Th in these six standards results from incomplete purification during production.

scholarly journals Establishing SI-Traceability of Nanoparticle Size Values Measured with Line-Start Incremental Centrifugal Liquid Sedimentation

Separations ◽  
2019 ◽  
Vol 6 (1) ◽  
pp. 15
Author(s):  
Vikram Kestens ◽  
Victoria A. Coleman ◽  
Jan Herrmann ◽  
Caterina Minelli ◽  
Alex G. Shard ◽  
...  
Keyword(s):  
Particle Size ◽  
Certified Reference Materials ◽  
International System ◽  
Metrological Traceability ◽  
Metrological Reliability ◽  
Limited Information ◽  
System Of Units ◽  
Si Traceability ◽  
Calibration Materials ◽  
Traceability Networks

Line-start incremental centrifugal liquid sedimentation (disc-CLS) is a powerful technique to determine particle size based on the principles of Stokes’ law. As most input quantities of the Stokes equation cannot be easily determined for typical instruments used for this method, an alternative method which depends on calibrating the sedimentation time scale with reference particles has become common practice. Unfortunately, most of these calibration materials (calibrants) come with limited information regarding their metrological reliability (e.g., lack of measurement uncertainties and traceability statements, incomplete measurand definitions). As a consequence, routine particle size results obtained by disc-CLS are mostly only traceable to the calibrant used, and effective comparisons can only be made for those results originating from measurements performed with the same types of calibrants. In this study, we discuss the concept of metrological traceability and demonstrate that particle size results obtained by disc-CLS can be traceable to the ultimate metrological reference, i.e., the unit of length in the International System of Units (SI), the meter. Using the example of two colloidal silica certified reference materials, we describe how laboratories can realize metrological traceability to the SI by simplifying complex traceability networks.

The International System of Units (S.I.) and its Application to Clinical Chemistry

1974 ◽  
Vol 19 (6) ◽  
pp. 269-277
Author(s):  
L. G. Whitby
Keyword(s):  
Medical Practice ◽  
Clinical Chemistry ◽  
International System ◽  
Numerical Data ◽  
National Programme ◽  
Laboratory Staff ◽  
Si Units ◽  
Chemical Measurements ◽  
System Of Units ◽  
Educational Programmes

As part of the national programme of metrication, clinical chemistry laboratories in the U.K. are in process of changing their methods of reporting results so as to express them in SI units. This article gives examples of the effects of adopting SI units on the numerical expression of chemical results, and discusses practical aspects which may facilitate their introduction and acceptance in medical practice. For many chemical measurements, the change to SI units will cause substantial alterations in the numerical data with which clinicians will have to deal, and awareness of this fact will be necessary if serious mistakes in the management of patients' illnesses are to be avoided. The tasks of laboratory staff in planning and carrying out the necessary educational programmes are considered.

Certified Reference Material for Use in 1H, 31P, and 19F Quantitative NMR, Ensuring Traceability to the International System of Units

2017 ◽  
Vol 100 (5) ◽  
pp. 1365-1375 ◽  
Author(s):  
Romana Rigger ◽  
Alexander Rück ◽  
Christine Hellriegel ◽  
Robert Sauermoser ◽  
Fabienne Morf ◽  
...  
Keyword(s):  
High Performance ◽  
Certified Reference Materials ◽  
International System ◽  
National Metrology Institute ◽  
Quantitative Nmr ◽  
Iso Guide 34 ◽  
International System Of Units ◽  
System Of Units ◽  
Application Fields

Abstract In recent years, quantitative NMR (qNMR) spectroscopy has become one of the most important tools for content determination of organic substances and quantitative evaluation of impurities. Using Certified Reference Materials (CRMs) as internal or external standards, the extensively used qNMR method can be applied for purity determination, including unbroken traceability to the International System of Units (SI). The implementation of qNMR toward new application fields, e.g., metabolomics, environmental analysis, and physiological pathway studies, brings along morecomplex molecules and systems, thus making use of 1H qNMR challenging. A smart workaround is possible by the use of other NMR active nuclei, namely 31P and 19F. This article presents the development of three classes of qNMR CRMs based on different NMR active nuclei (1H, 31P, and 19F), and the corresponding approaches to establish traceability to the SI through primary CRMs from the National Institute of Standards and Technology and the National Metrology Institute of Japan. These TraceCERT® qNMR CRMs are produced under ISO/IEC 17025 and ISO Guide 34 using high-performance qNMR.

scholarly journals Quantitative NMR as a Versatile Tool for the Reference Material Preparation

2021 ◽  
Vol 7 (1) ◽  
pp. 15
Author(s):  
Kihwan Choi ◽  
Sangki Myoung ◽  
Yejin Seo ◽  
Sangdoo Ahn
Keyword(s):  
Reference Material ◽  
International System ◽  
Measurement Techniques ◽  
Purity Determination ◽  
Material Development ◽  
System Of Units ◽  
Versatile Tool ◽  
Quantitative Nuclear Magnetic Resonance ◽  
Multidimensional Methods ◽  
Material Preparation

The assessment of primary calibrator purity is critical for establishing traceability to the International System of Units (SI). Recently, quantitative nuclear magnetic resonance (qNMR) has been used as a purity determination method for reference material development, and many related measurement techniques have been designed to acquire accurate and reliable results. This review introduces the recent advances in these techniques (including multidimensional methods), focusing on the application of qNMR to reference material preparation.

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