Robust Nuclear Magnetic Resonance Research Articles

Robust Nuclear Magnetic Resonance (NMR) Spectroscopy Method for the Identification and Quantification of Phthalates in Fragments of Polyvinyl Chloride (PVC) Toys

An efficient nuclear magnetic resonance (NMR)-based method was developed to detect and quantify the presence of phthalates in plastic fragments obtained from a children’s toy and cosmetic product containers. Bis-2-ethyl hexyl phthalate (BEHP) was present at a concentration of 8.5% w/w in the plastic toy residue. This indicates levels of phthalates above the permitted threshold (e.g., <0.1% w/w) imposed by EU and USA regulations restricting the use of plasticizers in plastic toys for children aged 0 to 3 years. An added value of this method is that the tetramethylsilane (TMS) internal standard present at a concentration of 2.2 mmol/L in commercially available CDCl3 solvents may be conveniently used for the quantitative nuclear magnetic resonance (qNMR) analysis. The protocol described here is highly reproducible and may be easily applied to large scale investigations of plasticizers content into polyvinyl chloride (PVC) polymers.

Optimization of nuclear magnetic resonance and gas chromatography-mass spectrometry-based fingerprinting methods to characterize goat milk powder

This study is the first to provide a comprehensive characterization of the liquid and volatile fractions of whole goat milk powder (GMP). Robust nuclear magnetic resonance (NMR)- and gas chromatography-mass spectrometry (GC-MS)-based chemical fingerprinting methods were optimized and implemented. The untargeted 1H-NMR analysis resolved 44 metabolites in the liquid fractions of GMP. The NMR fingerprinting technique effectively identified metabolites coming from the aliphatic, sugar, and aromatic regions that can be important in defining the technological properties and quality of the GMP. The untargeted headspace gas chromatography-mass spectrometry fingerprinting was able to detect a total of 50 volatiles including alkanes, ketones, alcohols, aromatics, alkenes, aldehydes, esters, acid, and sulfur compounds. The GMP was dominated by volatiles in the alkane group, while only a few esters were detected. Goat milk is a premium product and vulnerable to fraudulent activities such as adulteration or counterfeit. Therefore, proper characterization and identification is a crucial first step to verify its authenticity and quality.

A robust nuclear magnetic resonance workflow for quantitative determination of petrophysical properties from drill cuttings

Determination of petrophysical parameters from surface measurements of drill cuttings, rather than well logs, has long been a subject of interest in the petroleum industry. Analysis of cuttings is presently included in mud logging workflows, although the methods employed tend to be labor-intensive and inefficient with an emphasis on qualitative lithological and mineralogical descriptors. Nuclear magnetic resonance (NMR) has the potential to deliver rapid formation evaluation at the rig site for near-real-time completion decisions. Despite numerous efforts to demonstrate NMR cuttings analysis, dating back to the 1980s, the technique has yet to achieve commercial success. We suggest this failure is due not to the physics of the measurement, which is understood, but rather to inadequate sample preparation. By centrifuging brine-saturated cuttings from conventional formations under a per-fluorinated oil, and using multinuclear NMR to measure liquid volumes, we obtain accurate porosity and permeability values independent of other measurements. Our robust workflow removes the inconsistencies associated with manual sample preparation. We present two case studies and the important requirements for handling actual drill cuttings.

Quantum computing gates via optimal control

We demonstrate the use of optimal control to design two entropy-manipulating quantum gates which are more complex than the corresponding, commonly used, gates, such as CNOT and Toffoli (CCNOT): A two-qubit gate called polarization exchange (PE) and a three-qubit gate called polarization compression (COMP) were designed using GRAPE, an optimal control algorithm. Both gates were designed for a three-spin system. Our design provided efficient and robust nuclear magnetic resonance (NMR) radio frequency (RF) pulses for 13 C 2-trichloroethylene (TCE), our chosen three-spin system. We then experimentally applied these two quantum gates onto TCE at the NMR lab. Such design of these gates and others could be relevant for near-future applications of quantum computing devices.