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Westwood S, Lippa K, Shimuzu Y, Lalerle B, Saito T, Duewer D, Dai X, Davies S, Ricci M, Baldan A, Lang B, Sarge S, Wang H, Pratt K, Josephs R, Mariassy M, Pfeifer D, Warren J, Bremser W, Ellison S, Toman B, Nelson M, Huang T, Fajgelj A, Gören A, Mackay L, Wielgosz R. Methods for the SI-traceable value assignment of the purity of organic compounds (IUPAC Technical Report). PURE APPL CHEM 2023. [DOI: 10.1515/pac-2020-0804] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Abstract
The “purity” of an organic compound typically refers, in practice, to an assignment of the mass fraction content of the primary organic component present in the material. The “purity” value of an organic primary calibrator material is the ultimate source of metrological traceability of any quantitative measurement of the content of that compound in a given matrix. The primary calibrator may consist of a Certified Reference Material (CRM) whose purity has been assigned by the CRM producer or a laboratory may choose to value-assign a material to the extent necessary for their intended application by using appropriately valid methods. This report provides an overview of the approach, performance and applicability of the principal methods used to determine organic purity including mass balance, quantitative NMR, thermal methods and direct-assay techniques. A statistical section reviews best practice for combination of data, value assignment as the upper limit values corresponding to 100 % purity are approached and how to report and propagate the standard uncertainty associated with the assigned values.
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Affiliation(s)
- Steven Westwood
- Bureau International des Poids et Mesures (BIPM) , Sèvres , France
| | - Katrice Lippa
- National Institute of Standards and Technology (NIST) , Gaithersburg , MD , USA
| | | | - Beatrice Lalerle
- Laboratoire Nationale de Métrologie et d’Essais (LNE) , Paris , France
| | - Takeshi Saito
- National Metrology Institute of Japan (NMIJ) , Tsukuba , Japan
| | - David Duewer
- National Institute of Standards and Technology (NIST) , Gaithersburg , MD , USA
| | - Xinhua Dai
- National Institute of Metrology (China) (NIM) , Beijing , China
| | - Stephen Davies
- National Measurement Institute Australia (NMIA) , North Ryde , NSW , Australia
| | | | - Annarita Baldan
- Nederlands Metrologisch Instituut (VSL) , Delft , The Netherlands
| | - Brian Lang
- National Institute of Standards and Technology (NIST) , Gaithersburg , MD , USA
| | - Stefan Sarge
- Physikalisch-Technische Bundesanstalt (PTB) , Braunschweig , Germany
| | - Haifeng Wang
- National Institute of Metrology (China) (NIM) , Beijing , China
| | - Ken Pratt
- National Institute of Standards and Technology (NIST) , Gaithersburg , MD , USA
| | - Ralf Josephs
- Bureau International des Poids et Mesures (BIPM) , Sèvres , France
| | | | - Dietmar Pfeifer
- Bundesanstalt für Materialforschung und -Prüfung (BAM) , Berlin , Germany
| | | | - Wolfram Bremser
- Bundesanstalt für Materialforschung und -Prüfung (BAM) , Berlin , Germany
| | | | - Blaza Toman
- National Institute of Standards and Technology (NIST) , Gaithersburg , MD , USA
| | - Michael Nelson
- National Institute of Standards and Technology (NIST) , Gaithersburg , MD , USA
| | - Ting Huang
- National Institute of Metrology (China) (NIM) , Beijing , China
| | - Ales Fajgelj
- International Atomic Energy Agency , Vienna , Austria
| | - Ahmet Gören
- Kimya Bölümü, Gebze Teknik Üniversitesi , Gebze , Turkey
| | - Lindsey Mackay
- National Measurement Institute Australia (NMIA) , North Ryde , NSW , Australia
| | - Robert Wielgosz
- Bureau International des Poids et Mesures (BIPM) , Sèvres , France
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Singh N, Taibon J, Pongratz S, Geletneky C. Quantitative NMR (qNMR) spectroscopy based investigation of the absolute content, stability and isomerization of 25-hydroxyvitamin D2/D3 and 24(R),25-dihydroxyvitamin D2 in solution phase. Sci Rep 2022; 12:3014. [PMID: 35194108 PMCID: PMC8863798 DOI: 10.1038/s41598-022-06948-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Accepted: 02/09/2022] [Indexed: 11/18/2022] Open
Abstract
Vitamin D is an important parameter, in serum/plasma based diagnostic analysis, for the determination of optimal regulation of calcium and phosphate homeostases in the human body, vital for the monitoring/progression of osteomalacia and rickets. Particularly, the quantification of 25-hydroxyvitamin D2, 25-hydroxyvitamin D3 and 24R,25-dihydroxyvitamin D in blood is an excellent indicator for the vitamin D status of a patient. For this purpose, LC–MS/MS methods, based on appropriate vitamin D reference standards, are considered to be ‘gold standard’ for such measurements. We have utilized quantitative NMR spectroscopy to determine the absolute content of these molecules, available as non-certified chemicals, and have determined the stability of these callibrators in borderline polar solvents at room temperature. We have observed significant isomerization of the analytes, which can play a big role in quantification of these analytes by hyphenated LC and GC analytical techniques. Appropriate explanations are given for the observation of new impurities with time in solution phase. The spin system selected for quantitation was determined using relevant 1D and 2D NMR pulse sequences. The advantage of the qNMR approach is that it is based on the quantification of atoms rather than molecular properties (e.g., quantitation by LC/UV, GC, etc.). Since the signals in an NMR spectrum are different nuclear spin-systems dispersed precisely in a magnetic environment, with the intensity being directly proportional to the amount of a particular type of nuclear spin, this technique delivers unparalleled information about the chemical structure and the absolute content.
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Affiliation(s)
- Neeraj Singh
- Roche Diagnostics, Nonnenwald 2, 82377, Penzberg, Germany.
| | - Judith Taibon
- Roche Diagnostics, Nonnenwald 2, 82377, Penzberg, Germany
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Pitarch-Motellón J, Roig-Navarro AF, Le Goff C, Cavalier E, Fabregat-Cabello N. Re-certification of hydroxyvitamin D standards by isotope pattern deconvolution. J Chromatogr B Analyt Technol Biomed Life Sci 2019; 1120:89-94. [PMID: 31071583 DOI: 10.1016/j.jchromb.2019.04.043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Revised: 04/01/2019] [Accepted: 04/21/2019] [Indexed: 10/27/2022]
Abstract
BACKGROUND Vitamin D testing in analytical clinical laboratories has been experiencing a rapid increase of demand over the last years, as it plays a key role in several disorders. Due to the narrow ranges of medical significance regarding its concentration levels in human serum, accurate and precise determinations of vitamin D metabolites are required. METHODS We present an isotope dilution mass spectrometry quantification method for the re-certification of routine commercial standards used in method validation steps, isotope pattern deconvolution (IPD) based on LC-MS/MS. RESULTS IPD allowed to compensate for the observed biases of +4.7% for 25(OH)D3, -29% for 25(OH)D2 and -30% for 24,25(OH)2D3 standard concentrations, respectively in an easy, cheap and straightforward way. CONCLUSIONS Is has been observed that, in some cases, discrepancies may exist between stated purity or amount of routinely used commercial standards and actual values, which would lead to unwanted bias in the developed methodologies. The present correction has helped meeting the regulations established by international standardization programs, including Vitamin D Standardization Program (VDSP).
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Affiliation(s)
- J Pitarch-Motellón
- Research Institute for Pesticides and Water, Universitat Jaume I, Castelló, Spain
| | - A F Roig-Navarro
- Research Institute for Pesticides and Water, Universitat Jaume I, Castelló, Spain
| | - C Le Goff
- Department of Clinical Chemistry, University of Liège, CHU Sart-Tilman, Liège, Belgium
| | - E Cavalier
- Department of Clinical Chemistry, University of Liège, CHU Sart-Tilman, Liège, Belgium
| | - N Fabregat-Cabello
- Department of Clinical Chemistry, University of Liège, CHU Sart-Tilman, Liège, Belgium.
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