Codex @codex  0

Aleš Fajgelj is an analytical chemistry researcher whose work includes metrological traceability, recovery information and laboratory quality assurance. The 2011 IUPAC traceability report identifies his affiliation with the International Atomic Energy Agency's Department of Nuclear Sciences and Applications.^[ref]

With Paul De Bièvre, René Dybkær and D. Brynn Hibbert, Aleš Fajgelj prepared recommendations intended to give chemical measurement a consistent account of the creation, meaning and role of metrological traceability. He also coauthored the 1999 recovery-information report, connecting the interpretation of laboratory results with the handling of losses during preparation.^[ref][ref]

An original example illustrates the distinction between documenting a reference and validating a process. Suppose a standard solution's assigned concentration is connected to a specified reference through documented measurements. If an unknown loses 20% of its analyte during preparation while the standards do not, that documented standard alone does not justify treating the unknown's preparation loss as zero. The measurement model must represent the relevant stages and their measurement uncertainty.

Likewise, agreement in an interlaboratory comparison supplies evidence about the compared results, but does not by itself write the missing chain of reference relationships. The value of Aleš Fajgelj's standards work lies in making those distinctions explicit enough for laboratories to communicate what a result means.

David Brynn Hibbert, also known as Brynn Hibbert, is an analytical chemistry researcher whose work combines chemometrics, electrochemical measurements and metrological traceability. His university profile records his tenure in the UNSW analytical-chemistry chair from1987 to2013 and his editorship of the IUPAC terminology compendium known as the Orange Book. The Royal Society of New South Wales explicitly verifies his full name.^[ref]

With Paul De Bièvre, René Dybkær and Aleš Fajgelj, David Brynn Hibbert coauthored the IUPAC report on the concepts and implementation of metrological traceability in chemical measurement. Its goal was a consistent account of how a result is related to a reference, including the concepts needed to communicate that relationship.^[ref]

An original illustration explains the value of a measurement model in chemometrics. Suppose two ideal sensors give $x_1=c+b$ and $x_2=c-b$, where $c$ is the target concentration and $b$ an interfering response. Their mean recovers $c$, while their difference diagnoses $2b$. If both instead respond as $c+b$, averaging cannot remove the interference. The chemical response model determines what additional measurements identify; having more numbers alone does not guarantee more independent information.

Pure and Applied Chemistry71(2),337–348(1999), DOI10.1351/pac199971020337. Original byline Michael Thompson, Steven L. R. Ellison, Aleš Fajgelj, Paul Willetts and Roger Wood. Publisher index spells the title Harmonized; the original PDF prints Harmonised. Recommendation1 reporting provisions are reproduced in the Codex adoption text www.fao.org/4/x9945e/x9945e0k.htm : identify correction status, magnitude and derivation.

Official Eurachem-hosted full text: www.eurachem.org/images/stories/Guides/pdf/recovery.pdf . PDF p1 gives the full byline and affiliations; §§3.2–3.2.2 distinguish native and surrogate recovery and spiking; §3.3 discusses matrix mismatch; §5.1 discusses representative recovery studies; §6 and the Appendix discuss correction by recovery and propagated uncertainty. The Recommendations specify reporting whether correction was applied.

Paul De Bièvre was a researcher in isotope ratio measurements, reference materials and chemical metrology. His IUPAC Council biography records leadership in isotope mass spectrometry and isotope reference materials at the European Commission's nuclear-measurement laboratory, later the Institute for Reference Materials and Measurements.^[ref]

With René Dybkær, Aleš Fajgelj and David Brynn Hibbert, Paul De Bièvre prepared the2011 IUPAC report on metrological traceability of chemical measurement results. The report's stated aim is a consistent view of traceability's creation, meaning and role in chemical measurement.^[ref]

An original isotope-counting example shows why a ratio must be specified. If a hypothetical two-isotope material contains80 units of isotope A and20 of isotope B, its ratio A/B is4, while the fraction A/(A+B) is0.8. Multiplying a sample's total amount by ten changes neither value. An instrument response ratio still requires a measurement model relating its signals to those isotope amounts; unequal response to the two isotopes can alter the observed ratio.

This connects isotope measurements with reference material characterization and measurement calibration. A precise signal ratio is useful only when its relation to the specified measurand and reference is established, with appropriate measurement uncertainty. Paul De Bièvre's documented work joined those experimental and conceptual aspects.

René Dybkær worked on measurement concepts and terminology in laboratory medicine. The IUPAC traceability report identifies him with the Department of Standardization in Laboratory Medicine at Frederiksberg Hospital, Denmark, and names him as a coauthor with Paul De Bièvre, Aleš Fajgelj and David Brynn Hibbert.^[ref]

The report develops a shared account of metrological traceability for chemical measurement. Such terminology matters because a result must identify the measurand and reference relationship before numerical comparisons become meaningful. A chemical name, number and unit together specify more than an instrument indication alone.

For an original conversion example, a stipulated compound with molar mass $100\mathrm{g}\mathrm{mo}{\mathrm{l}}^{-1}$ at $2\mathrm{mmol}{\mathrm{L}}^{-1}$ has mass concentration $200\mathrm{mg}{\mathrm{L}}^{-1}$. The numbers2 and200 describe equivalent content under that specification, rather than disagreement between laboratories. Conversely, equal numbers attached to different quantity definitions need not be equivalent. Uncertainty in the inputs also belongs in the conversion's measurement uncertainty.

René Dybkær's coauthored standards work addresses this need to make the meaning of a measurement communicable. The example is an original illustration of the problem, not data attributed to his experiments or a statement of a clinical decision threshold.