A discussion about the potentials and pitfalls of quantitative nuclear magnetic resonance (qNMR) spectroscopy in food science and beyond

Abstract

a discussion session entitled "Quantitative nuclear magnetic resonance (qNMR)" was organized. The conference participants had the opportunity to submit written questions as well as to ask ad-hoc questions during the session, which were to be answered by a panel of qNMR experts from several application fields. This article provides an edited and referenced transcript of the session. The major topics were centred on instrumental requirements for qNMR, and the participants were in agreement that modern digital NMR spectrometers guarantee a long-term stability of measurements and calibrations, sometimes over several years. However, the panel also agreed that method validation is an absolute necessity in qNMR as in every other field of quantitative analytical chemistry. Validation strategies may depend on the purpose of the method and vary between multi-component analyses of foods and beverages, compared to single target assays e.g. in verification of reference standards. Approaches to establish limits of detection and to ensure the required method accuracy were suggested. The discussion was closed with a general agreement of the experts that qNMR in food science will gain a wider application range in the future. The necessity to abolish regulatory hindrances -including the approval of using qNMR in reference methods -was stressed.Introduction N uclear magnetic resonance (NMR) spectroscopy has occasionally been used for quantification since the 1960s (see Figure 1 and the overview in Bharti & Roy 1 , however only the advancements of digital spectrometer technology during the last two decades have made this technique available for routine analysis in competition to the commonly used chromatographic methods for quantification of compounds in food science. Only very few applications of quantitative NMR (qNMR) were published till the mid-1990s, and since then an exponential growth in development of applications in this area can be seen (Figure 1), which still has not reached a saturation or plateau. . The participating experts were: ■ Torsten Schönberger (TS) who works for the Bundeskriminalamt (BKA) in Wiesbaden, Germany, at the Forensic Science Institute. His main interests with qNMR are not only the analysis of drugs including illicit drugs but also pharmaceuticals, doping, plastics, and explosives, among other forensic materials [5][6][7][8] . ■ Sebastian Ehni (SE) who works at ChemCon GmbH in Freiburg,Germany, a manufacturer of pharmaceutical active ingredients to be applied at humans. SE is using NMR spectroscopy and quantitative NMR spectroscopy in quality control [9][10][11] . ■ Manfred Spraul (MS), the chief technology officer of the new Applied Industrial Clinical (AIC) division of Bruker BioSpin, Rheinstetten, Germany. AIC includes not only a large part of food science developments but also clinical applications and other areas such as cosmetics that might be included in the future [12][13][14][15][16] . ■ Birk Schütz (BS), the head of the method development team for food analysis, also from Bruker BioSpin [17...

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