Back in October we presented a talk at Gulf Coast Conference that concerned the prediction of the chemical and physical properties of heavy petroleum feeds being converted to higher value product in a residual catalytic cracker (RCC). Over the years we have analyzed these materials by 300 and 60 MHz NMR and obtained good PLS-regression models that can adequately predict properties for real-time process control and optimization in a petroleum refinery. With the advent of a large number of new benchtop NMR systems we have been convincing ourselves that these types of analyses can be performed by systems such as the Magritek Spinsolve 43 MHz. We ran a series of samples that had been sitting around our lab for 15 years by dissolving them at about 50 volume% in a 50/50 CDCl3/CS2 solvent system. For each sample we had laboratory test data for a number of chemical and physical properties of interest to process engineers. We regressed the lab data variability against the variability in the Magritek 43MHz 1H NMR spectra and obtained cross-validated PLS models. The presentation material is given here at this link – Gulf Conference Presentation – 43 MHz RCC Feedstream Regression Models
Benchtop NMR Systems – Sensitivity with Complex Pharmaceutical Molecules
PNA has been conducting a number of studies into the adulteration of male enhancement herbal suplements with PDE5 inhibitors such as viagra, cialis and a wide number of analogs (Mw approximately 475 amu). Standard materials for the analogs are quite expensive so in th eprocess of developing ID and purity methods on our NMR systems we ran the 1H NMR on our 300, 60, and 43 MHz NMR systems at a concentration of 5mg/ml which equates to 0.01 Molar. This PDF of the NMR data demonstrates the sensitivity and resolution obtainable on these bench-top 5mm NMR systems. They can readily look at samples at these concentrations. They can readily be utilized as screening tools or as quantitation and identification analyzers.
The PDF file containing the Varian 300, Aspect-60, and Magritek 43 MHz data can be found here: NMR Data-0.01 Molar_PDE5 Analogs 300_60_43_MHz
Beer and Cider Analysis – Example of Spectral Repeatability of Benchtop 60 MHz NMR System
Here is an example of spectral reproducibility. We are doing a lot of beer NMR at the moment on our 300 MHz NMR and for “giggles” we are running many samples through the various bench-top systems in our lab. We have been quantifying small organic acids (lactic, acetic, succinic , malic, citric, etc.) as they can give some idea of yeast activities and health during fermentation. We are also quantifying and studying the 1,4/1,6 linkage distribution of residual dextrins. The series of superimposed spectra below consists of 28 spectra of a freeze dried beer sample (a unique Belgian Dubbel. Each spectrum was 128 pulses and took approximately 30 minutes per spectrum. So the superimposed data represents a 14 hour continuous stability test.The data was automatically processed with 16K zero-fill and autophase.It looks pretty damn good.
We’ve been looking at a lot of sour beers – here is a home-brewed Flemish Red aged in an oak barrel – note the high lactic and acetic content.
We’ve also been analyzing a lot of hard ciders – commercial and home-brewed varitieties of various styles – very different from one sample to another in the small molecule and sugar chemistry.
1H qNMR at 300MHz or 60 MHz can be utilized to identify and quantify small molecule chemistry in fermentations. Below is an example of a quantitative chemistry report on a series of ciders.
Beer and Cider Analysis is offered with similar quantitative results is offered for $100 per sample in our analytical lab.
Benchtop NMR – Screening Tool for Adulterated Herbal Supplements
Survey of Low Field NMR Spectrometer Platforms for Successful Screening of Sexual Enhancement and Weight Loss Supplements for Adulteration with Drugs and Drug Analogs
John C Edwards1, Kristie M Adams2, and Anton Bzhelyansky2
1Process NMR Associates, Danbury, CT
2United States Pharmacopeial Convention, Rockville, MD
The adulteration of dietary supplements (or natural health products) with synthetic pharmaceuticals is an area of increasing concern, which presents substantial risk to public health. Widely available in retail and via the Internet, these products are often marketed as sexual enhancement, weight loss and/or bodybuilding supplements. Unlike prescription drugs, supplements do not require premarket approval by FDA before they are made available for public consumption. In fact, the agency can only take investigational action after the adulterated product has caused harm and the adverse event has been reported via MedWatch (FDA’s online portal for voluntary reporting of adverse events associated with drugs, medical devices and dietary supplements).
Development of analytical tools for screening and identification of adulterated products in the marketplace represents a significant step forward in the fight against adulterated dietary supplements. Several organizations, including AOAC and USP, have undertaken initiatives to evaluate and recommend analytical methodologies for screening supplements for adulteration. HPLC and mass spectrometry have so far dominated the screening and quantitation studies published in the literature, with NMR spectroscopy often relegated to the status of structure elucidation tool. In this work, we investigate the ability of several-low field NMR spectrometric platforms to successfully identify and quantify the presence of adulterating drug substances in sexual enhancement and weight loss supplements purchased online and in US retail. 1H qNMR of both types of samples was performed with 300 MHz NMR to confirm the presence of adulterants such as sildenafil, tadalafil, and their structural analogues (sexual enhancement supplements) and various synthetic stimulants (weight loss supplements). We have concluded that a simple sample preparation protocol combined with straightforward 1H NMR spectroscopic analysis yields a rapid, robust and reliable screening test for adulterated supplements, presenting an attractive alternative to more labor-intensive, expensive and expertise-demanding techniques du jour.
This was presented by John Edwards at SMASH in September 2014, and at the Carolina NMR Symposium in November 2014
presentation can found here: Benchtop NMR – Herbal Supplement Adulteration Screening
1H Benchtop NMR Analysis of Physical and Chemical Properties of Diesel Fuel
1H Benchtop NMR has great potential to increase the throughput of both routine and emergency fuel sample analysis in refinery laboratories. Currently fuel samples must be passed through multiple dedicated analyzers to obtain information such as density, H-Content, aromatics, olefins, saturates, benzene,
Octane numbers, cetane index, cetane number, distillation curves, vapor pressure, flash point, pour point, freeze point, cloud point, etc. Correlation of the 1H NMR spectra of these refinery fuel samples to these primary test results will allow all parameters to be predicted in about 40 seconds from the 4 pulse spectrum of the pure fuel. Here we have a few examples obtained on some diesel fuels that were submitted to our lab for ASTM D7171 – Hydrogen Content by TD-NMR. We had density, H-content, and aromatics wt% by GC. Below are three example correlation obtained on the Picospin 80 system (that requires 32 pulses per sample due to the capillary sample size). The results were very similar for the 300, 60, and 42 MHz data obtained on the three other NMR system in our laboratory. The comparative results are shown in Table II. The results are very similar independent of the field strength of the NMR system. The data from all 4 NMR systems is provided in this section.
