Rheinstetten, Germany
Rheinstetten, Germany

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Monakhova Y.B.,Chemisches und Veterinaruntersuchungsamt CVUA Karlsruhe | Monakhova Y.B.,BrukerBiospin GmbH | Monakhova Y.B.,Chernyshevsky Saratov State University | Schutz B.,BrukerBiospin GmbH | And 5 more authors.
Accreditation and Quality Assurance | Year: 2014

Laboratories intending to work as official laboratories for food control have to be accredited according to ISO/IEC 17025. This necessitates the use of validated analytical methods. In this study, we present validation results of the recently commercialized "JuiceScreener" based on nuclear magnetic resonance (NMR) spectroscopy with apple juice as application example. The quantitative analysis included 29 compounds such as major sugars, amino acids, organic acids, as well as acetoin, arbutin, benzaldehyde, hydroxymethylfurfural, acetaldehyde, methanol, and ethanol. Limit of detection (LOD), limit of quantification (LOQ), coefficients of variation (CV) for replicated measurements, repeatability, linear range, and recoveries were determined. The LOD and LOQ values varied in the 0.48-16 mg/L and in the 1.9-122 mg/L ranges with the lowest values for shikimic acid and highest for the principal sugars. The 1H NMR assays were linear in broad concentration ranges (R > 0.99), encompassed typical concentration in apple juices, and are sufficient to control the requirements of the code of practice of the European fruit juice association. Recoveries between 92 and 109 % on average for five separate standard additions were obtained. The average CVs were found to be 3.0 % (intraday) and 3.6 % (interday) excluding sample preparation (by measuring five time one solution) and 5.5 % (intraday) and 6.2 % (interday) including sample preparation (by preparing and analyzing five separate samples). The NMR method was judged as suitable for the simultaneous quantification of compounds in apple juice for official food control purposes. Our results show that multiparameter NMR methods can be successfully validated with standard instrumentarium and that they are fit for the purpose of official food control. © 2013 Springer-Verlag Berlin Heidelberg.

Martin G.E.,Merck And Co. | Williamson R.T.,Merck And Co. | Dormer P.G.,Merck And Co. | Bermel W.,BrukerBioSpin GmbH
Magnetic Resonance in Chemistry | Year: 2012

ADEQUATE experiments provide an alternative to the more commonly employed GHMBC experiment for the establishment of long-range heteronuclear connectivities. The 1,1-ADEQUATE experiment allows the unequivocal identification of both protonated and non-protonated carbon resonances adjacent to a protonated carbon. The 1,n-ADEQUATE experiment establishes correlations via an initial 1J CH heteronuclear transfer followed by an nJ CC out-and-back transfer, most typically, via three carbon-carbon bonds. Hence, the 1,n-ADEQUATE experiment allows the equivalent of 4J CH heteronuclear correlations to be probed when they are not observed in a GHMBC spectrum. Aside from the lower sensitivity of the 1,n-ADEQUATE experiment relative to GHMBC experiments, the interpretation of the former is also complicated by the 'leakage' of 1J CC correlations into the spectrum that must be identified. A method for the inversion of 1J CC correlations to facilitate the interpretation of 1,n-ADEQUATE spectra is presented that allows a single experiment to be performed to access 1J CC and nJ CC correlation information. Copyright © 2012 John Wiley & Sons, Ltd.

Reibarkh M.,Merck And Co. | Williamson R.T.,Merck And Co. | Martin G.E.,Merck And Co. | Bermel W.,BrukerBioSpin GmbH
Journal of Magnetic Resonance | Year: 2013

Establishing the carbon skeleton of a molecule greatly facilitates the process of structure elucidation, both manual and computer-assisted. Recent advances in the family of ADEQUATE experiments demonstrated their potential in this regard. 1,1-ADEQUATE, which provides direct 13C-13C correlation via 1JCC, and 1,n-ADEQUATE, which typically yields 3JCC and 1JCC correlations, are more sensitive and more widely applicable experiments than INADEQUATE and PANACEA. A recently reported modified pulse sequence that semi-selectively inverts 1JCC correlations in 1,n-ADEQUATE spectra provided a significant improvement, allowing 1JCC and nJCC correlations to be discerned in the same spectrum. However, the reported experiment requires a careful matching of the amplitude transfer function with 1JCC coupling constants in order to achieve the inversion, and even then some 1JCC correlations could still have positive intensity due to the oscillatory nature of the transfer function. Both shortcomings limit the practicality of the method. We now report a new, dual-optimized inverted 1JCC 1,n-ADEQUATE experiment, which provides more uniform inversion of 1JCC correlations across the range of 29-82 Hz. Unlike the original method, the dual optimization experiment does not require fine-tuning for the molecule's 1JCC coupling constant values. Even more usefully, the dual-optimized version provides up to two-fold improvement in signal-to-noise for some long-range correlations. Using modern, cryogenically-cooled probes, the experiment can be successfully applied to samples of ∼1 mg under favorable circumstances. The improvements afforded by dual optimization inverted 1JCC 1,n-ADEQUATE experiment make it a useful and practical tool for NMR structure elucidation and should facilitate the implementation and utilization of the experiment. © 2013 Elsevier Inc. All rights reserved.

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