Daniel J. Holland

Periodic porous structures manufactured using additive manufacturing are candidates for intensified process devices. Detailed measurements of the velocity field are required to characterize the turbulent mixing generated by flow through the channel network. We used time-resolved single-shot spiral magnetic resonance velocity (MRV) imaging to noninvasively record snapshots of the velocity field for water flowing through a Schwarz Diamond monolith. The time-resolved velocity data lend themselves to more detailed analysis than is possible with conventional time-averaged magnetic resonance methods. The turbulent energy spectra measured with MRV confirmed that the pore network places an upper size limit on the eddies that could exist in the flow. The − 5 / 3 power-law scaling from Kolmogorov theory was only attained at a Reynolds number around 2000, indicative of a higher transition point to a fully turbulent regime than is usually reported for random porous media. The local Reynolds stress tensor showed considerable anisotropy within the network, which affects mass transport to the channel surfaces. The time-resolved MRV method offers valuable insights into turbulence in porous media that can inform the design and operation of novel geometries.

Accurate pH determination is essential in winemaking, as pH influences microbial stability, fermentation kinetics, and sensory attributes. There is growing interest in analytical methods that reliably characterize grape must and provide real‐time insights into fermentation and product quality. We developed an analytical framework based on benchtop nuclear magnetic resonance (NMR) spectroscopy, in which a spectroscopically derived pH measurement enables a fully integrated approach to grape must analysis. Although electrode‐based pH measurement is well established, its need for direct sample contact and an additional sensing unit limits its integration into automated, noninvasive workflows. We therefore applied a model‐based data processing strategy that fits benchtop NMR spectra, quantifies grape must composition, and derives pH from tartaric acid's chemical shift variation. Analysis of 100 grape must samples for calibration and validation showed very good agreement between NMR‐derived and electrode‐based pH values. The method was further used to monitor pH changes during acidification, deacidification, and fermentation. These results highlight the potential of benchtop NMR, combined with advanced data‐analytical modeling, as a fully integrated tool for real‐time fermentation monitoring. Notably, analyzing grape must composition by NMR spectroscopy also allows the pH value to be determined directly, without the need for an additional pH electrode.

Simultaneous identification and quantification of illicit drugs can substantially reduce the reliance on multiple analytical instruments and lower operational costs. This study evaluates the capability of benchtop NMR spectroscopy for integrated qualitative and quantitative drug analysis. A 60 MHz benchtop NMR spectrometer was employed to examine blind and seized casework samples suspected to contain methamphetamine (MA) or 3,4-methylenedioxymethamphetamine (MDMA). Spectral data were processed using a novel peak-matching algorithm, followed by an approach based on Wasserstein distance and a quantum mechanical modelling (QMM) framework to enable simultaneous identification and quantification. The analytical performance of benchtop NMR was benchmarked against conventional techniques, with identification compared to FT-IR and GC–MS, and quantification compared to HPLC-UV and high-field NMR. The identification algorithm reliably identified the suspected drugs in all samples and detected associated adulterants in most cases. Quantitatively, for suspected drugs, the approach based on Wasserstein distance achieved a root mean square error (RMSE) of 3.8 mg analyte/100 mg sample and QMM achieved 1.3, compared to 1.4 for HPLC-UV and 1.6 for high-field NMR. For seized samples, RMSE values relative to HPLC-UV were 3.8 for Wasserstein distance approach and 1.5 mg analyte/100 mg sample for QMM. These results demonstrate that benchtop NMR can provide a rapid, cost-effective, and reliable analytical approach capable of simultaneous identification and quantification of analytes without the need for compound-specific calibration standards. This integrated approach demonstrates strong potential for forensic laboratories and harm-reduction centres conducting routine drug screening.

Heterogeneously catalyzed hydrogenations are pivotal in the chemical industry. Studying these reactions often demands significant experimental effort due to safety requirements, elevated pressures and temperatures, and the operational modes of traditional laboratory reactors. To address these challenges, we propose an automated, efficient, and cost‐effective method for characterizing such reactions within a kinetic laboratory setting. Utilizing benchtop NMR as a noninvasive, automatable analytical tool offers advantages in terms of space and cost over high‐frequency NMR, though its limited spectral resolution may restrict applicability to certain reaction systems. In this study, we investigate the hydrogenation of 2‐methyl‐3‐butyn‐2‐ol (MBY) to 2‐methyl‐3‐buten‐2‐ol (MBE) as a model reaction. While literature provides extensive data on the main components, the formation of side products remains inadequately explained. Conducting the reaction in a batch reactor, we assess the detection and quantification of side products. Samples withdrawn during hydrogenation are analyzed using benchtop NMR coupled with a quantum‐mechanical Bayesian quantitative NMR analysis, employing component knowledge to quantify mixtures through mathematical modeling. We collect kinetic data, gaining both qualitative and quantitative insights into the reaction network at temperatures up to 80°C and a pressure of 10 bar. Our findings demonstrate that the reaction mixture's composition can be quantitatively monitored in real‐time, facilitating the derivation of kinetic parameters. Despite the minor formation of various side products, we successfully quantify dimeric reaction products and evaluate process parameters influencing their formation. The integration of a reactor, online benchtop NMR, and advanced qNMR data analysis yields high‐quality results essential for process optimization.

Benchtop ¹ H NMR spectroscopy enables quantitative VLE measurements at near-ambient pressure by separately analysing the liquid and vapour phases to determine equilibrium compositions and pressures.

This study evaluates the feasibility of benchtop NMR spectroscopy for the quantitative analysis of methamphetamine hydrochloride in binary and ternary mixtures. A 60‐MHz benchtop NMR spectrometer was used to analyse samples containing methamphetamine hydrochloride at purities ranging from approximately 10 to 90 mg per 100 mg of sample, alongside cutting agents (methylsulfonylmethane, N‐isopropylbenzylamine hydrochloride, caffeine and phenethylamine hydrochloride) and an impurity (pseudoephedrine hydrochloride). Spectral data were processed using integration, global spectral deconvolution (GSD), quantitative GSD (qGSD), and a quantitative quantum mechanical model (QMM). The root mean square error (RMSE) for these methods ranged from 4.7‐mg analyte per 100 mg of sample for integration down to 1.3‐mg analyte per 100 mg of sample for QMM when determining methamphetamine hydrochloride purity across binary and ternary mixtures. To further assess performance, additional mixtures were analysed using benchtop NMR with QMM and HPLC‐UV, yielding RMSE values of 2.1 and 1.1, respectively, for methamphetamine hydrochloride purity quantification across all samples. While HPLC‐UV maintains greater precision, benchtop NMR with QMM offers a cost‐effective and robust alternative, enabling simultaneous quantification of active substances and impurities with reduced reliance on solvents and calibration standards. This study underscores the potential of benchtop NMR as a complementary tool in forensic science and for implementing a quantitative technique in harm‐reduction drug‐checking centres.