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qNMR metrology and current "primary" reference material activities

  • In general, most quantitative organic chemical measurements rely on the availability of highly purified compounds to act as calibration standards. The traceability and providence of these standards is an essential component of any measurement uncertainty budget and provides the final link of the result to the units of measurement, ideally the SI. The more recent increase in the use of qNMR for the direct assessment of chemical purity however can potentially improve the traceability and reduce the uncertainty of the measured chemical purity at a reduced cost and with less material. For example, the method has beneficially been used by National Metrology Institutes for comparisons including comparisons on CCQM (Consultative Committee for Amount of Substance: Metrology in Chemistry and Biology, www.bipm.org). First comparisons started 1998 with CCQM-P3 (Organics in solution) or CCQM-P35 (2002, EtOH in solution), were underpinned by a broad range of polarity and molecular size (CCQM–K55In general, most quantitative organic chemical measurements rely on the availability of highly purified compounds to act as calibration standards. The traceability and providence of these standards is an essential component of any measurement uncertainty budget and provides the final link of the result to the units of measurement, ideally the SI. The more recent increase in the use of qNMR for the direct assessment of chemical purity however can potentially improve the traceability and reduce the uncertainty of the measured chemical purity at a reduced cost and with less material. For example, the method has beneficially been used by National Metrology Institutes for comparisons including comparisons on CCQM (Consultative Committee for Amount of Substance: Metrology in Chemistry and Biology, www.bipm.org). First comparisons started 1998 with CCQM-P3 (Organics in solution) or CCQM-P35 (2002, EtOH in solution), were underpinned by a broad range of polarity and molecular size (CCQM–K55 series of purity studies including Valine, Aldrin, or Folic acid) and were continued with the recent pilot studies CCQM-P150 (2014, purity of Dimethyl sulfone) or CCQM-P150b (2017, purity of Pyributicarb). Traditional ‘indirect’ methods of purity analysis require that all impurities are identified and quantified, leading to a minimum of four individual analytical methods (organic impurities, water, solvents, inorganic residue). These multiple technique approaches measure an array of different chemical impurities normally present in purified organic chemical compounds. As many analytical methodologies have compound-specific response factors, the accuracy and traceability of the purity assessment is dependent on the availability of reference materials of the impurities being available. qNMR provides the most universally applicable form of direct purity determination without need for reference materials of impurities or the calculation of response factors but only exhibiting suitable NMR properties. The development of CRMs addressing qNMR specific measurement issues will give analysts compounds ideally suited for the analytical method and also provide full characterisation of qNMR related parameters to enable more realistic uncertainty budgets. These materials will give users the tools to exploit qNMR more easily and enable them to speed up analytical method development and reduce the time and financial burden of multiple analytical testing. Due to recent advances in technical developments of NMR instruments such as acquisition electronics and probe design, detection limits of components in liquid mixtures were improved into the lower ppm range (approx. 5–10 ppm amount of substance) qNMR studies increasingly attract broader interest.zeige mehrzeige weniger

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  • 2017-11-24_qNMR_BAM_Maiwald_f_print.pdf
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Metadaten
Autor*innen:Michael MaiwaldORCiD
Dokumenttyp:Vortrag
Veröffentlichungsform:Präsentation
Sprache:Englisch
Jahr der Erstveröffentlichung:2017
DDC-Klassifikation:Naturwissenschaften und Mathematik / Chemie / Analytische Chemie
Freie Schlagwörter:Comparison study; Direct purity determination; Primary reference material; Quantitative NMR spectroscopy; qNMR; qNMR metrology
Veranstaltung:qNMR Day
Veranstaltungsort:Politecnico di Bari, Bari, Italy
Beginndatum der Veranstaltung:24.11.2017
Enddatum der Veranstaltung:24.11.2017
URL:http://www.gidrm.org/index.php/activities/workshops/2017-workshops/qnmr-day-a-gidrm-organized-in-cooperation-with-girm
Verfügbarkeit des Dokuments:Datei im Netzwerk der BAM verfügbar ("Closed Access")
Datum der Freischaltung:27.11.2017
Referierte Publikation:Nein
Eingeladener Vortrag:Nein
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