Application of automated eightfold suppression of water and ethanol signals in <sup>1</sup>H NMR to provide sensitivity for analyzing alcoholic beverages

Monakhova, Yulia B.; Schäfer, Hartmut; Humpfer, Eberhard; Spraul, Manfred; Kuballa, Thomas; Lachenmeier, Dirk W.

doi:10.1002/mrc.2823

Cited by 91 publications

(84 citation statements)

References 20 publications

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“…The NMR protocol applied was previously described in detail [24]. In short, a shaped pulse sequence during the relaxation delay is applied to suppress the eight 1 H NMR frequencies of water and ethanol (the OH singlet of both water and ethanol, as well as the CH 2 quartet and CH 3 triplet of ethanol).…”

Section: Nmr Measurementsmentioning

confidence: 99%

“…The sequence of reference measurement for frequency determination followed by the suppression experiment is controlled by a macro in the acquisition software so that a measurement under full automation is possible. Compared with the standard water presaturation pulse program, the eightfold suppression allowed a significantly higher setting of receiver gain without receiver overflow, which significantly increased the signal-to-noise ratio by an average factor of 10 [24]. In addition to this 1D experiment, an additional experiment to acquire 2D spectra was used.…”

Section: Nmr Measurementsmentioning

confidence: 99%

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Rapid Quantification of Ethyl Carbamate in Spirits Using NMR Spectroscopy and Chemometrics

Monakhova

Kuballa

Lachenmeier

2012

ISRN Analytical Chemistry

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Ethyl carbamate (EC, urethane, C 2 H 5 OCONH 2 ) is a genotoxic carcinogen and is regularly found in fermented food products including alcoholic beverages. In this study, the rapid method of nuclear magnetic resonance (NMR) spectroscopy in combination with partial least squares (PLS) regression is applied for the first time to the analysis of ethyl carbamate in stone fruit spirits (n = 119) and unrecorded alcohols (n = 27) (analysis time only 15 min per sample). The PLS procedure was validated using an independent set of samples (n = 43, R 2 = 0.89, RMSE = 0.14 mg/L) in comparison to reference GC/MS/MS results. The NMR method was found to outperform other screening techniques based on NIR or FTIR regarding sensitivity and selectivity. The major advantage over GC/MS/MS, besides the reduced time of instrumental analysis, is that no sample preparation besides addition of buffer with internal standard is required, while for GC/MS/MS labour-intensive sample extraction is necessary prior to measurement.

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Section: Nmr Measurementsmentioning

confidence: 99%

Section: Nmr Measurementsmentioning

confidence: 99%

Rapid Quantification of Ethyl Carbamate in Spirits Using NMR Spectroscopy and Chemometrics

Monakhova

Kuballa

Lachenmeier

2012

ISRN Analytical Chemistry

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“…A suppression of eight frequencies (around 4.70 ppm for OH-group signal for both water and ethanol, 3.66 ppm for ethanol CH 2 quartet, and 1.18 ppm for the corresponding ethanol CH 3 triplet) was conducted. The measurement protocol was previously described in detail 8,9 . All 1 H-NMR spectra were automatically phase and baseline corrected using the Topspin 3.2 software package (Bruker BioSpin, Rheinstetten, Germany).…”

Section: Methodsmentioning

confidence: 99%

“…The technique has gained popularity in the screening of beverages for components for authentication purposes 3 , as well as routine analysis and rapid detection of potentially unsafe substances [4][5][6][7] . As a result of the minimal sample preparation and the short analysis time, the sample output is considerably increased compared to other approaches 1,[8][9][10] . The consumption of surrogate alcohol, a subgroup of unrecorded alcohol, continues to endanger public health in Russia 11 , mainly because of high ethanol content and lower prices compared to recorded alcohol.…”

Section: Introductionmentioning

confidence: 99%

Nontargeted nuclear magnetic resonance (NMR) analysis to detect hazardous substances including methanol in unrecorded alcohol from Novosibirsk, Russia

Häusler

Okaru

Neufeld

et al.

Proceedings of the XIII International Conference on the Applications of Magnetic Resonance in Food Science

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Nuclear magnetic resonance (NMR) spectroscopy was applied to the analysis of alcoholic products in the context of health and safety control. A total of 86 samples of unrecorded alcohol were collected in Novosibirsk and nearby cities in Russia. Sampling was based on interviews with alcohol dependent patients, and unrecorded alcohol thus defined included illegally or informally produced alcoholic products (e.g., counterfeit or home-made alcoholic beverages) or surrogate alcohol in the form of cosmetic or medicinal products and industrial non-beverage alcohol such as antifreeze (antifreeze windshield washer fluid). For sample preparation, addition of buffer and of a water/ethanol mixture was required as single step. To detect potentially harmful samples, a nontargeted approach based on principal component analysis (PCA) was applied. The PCA scores plot shows six conspicuous samples with highly divergent scores from the rest. These samples are antifreeze windshield washer fluids containing high amounts of methanol, with concentrations in a range between 7% and 48% vol. The antifreeze products were bought in regular retail sale and were claimed as "not containing methanol" on five out of six labels. Additionally, formic acid (1.1%) was observed in four of the alcohol-containing medicinal products. The major advantage of NMR over conventional methods is the fact that it not only provides the same quantitative data for specific compounds, but also allows rapid nontargeted screening for unknown contaminants.

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“…DL: There was another interesting question: is it possible to enhance a signal intensity of one component in a multi component mixture? It's not quite clear but I think the question goes in this way that you want to only quantify this one single signal and perhaps suppress the other signals like, we are doing with the alcohol suppression of several signals to improve the detectability of the other minor compounds 23,24 . MS: What you could do is a selective excitation, for example.…”

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confidence: 99%

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

Lachenmeier¹,

Schönberger²,

Ehni³

et al.

Proceedings of the XIII International Conference on the Applications of Magnetic Resonance in Food Science

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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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Application of automated eightfold suppression of water and ethanol signals in ¹H NMR to provide sensitivity for analyzing alcoholic beverages

Cited by 91 publications

References 20 publications

Rapid Quantification of Ethyl Carbamate in Spirits Using NMR Spectroscopy and Chemometrics

Rapid Quantification of Ethyl Carbamate in Spirits Using NMR Spectroscopy and Chemometrics

Nontargeted nuclear magnetic resonance (NMR) analysis to detect hazardous substances including methanol in unrecorded alcohol from Novosibirsk, Russia

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

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Application of automated eightfold suppression of water and ethanol signals in 1H NMR to provide sensitivity for analyzing alcoholic beverages

Cited by 91 publications

References 20 publications

Rapid Quantification of Ethyl Carbamate in Spirits Using NMR Spectroscopy and Chemometrics

Rapid Quantification of Ethyl Carbamate in Spirits Using NMR Spectroscopy and Chemometrics

Nontargeted nuclear magnetic resonance (NMR) analysis to detect hazardous substances including methanol in unrecorded alcohol from Novosibirsk, Russia

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

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Application of automated eightfold suppression of water and ethanol signals in ¹H NMR to provide sensitivity for analyzing alcoholic beverages