Process NMR

News - Dr. John Edwards of Process NMR Associates will be presenting the following 3 posters and invited talk at the 1st Practical Applications of NMR in Industry Conference (PANIC), Schaumburg, IL, October 15-17, 2012

Invited Talk

On-line Applications of 60 MHz High-Resolution NMR Systems in Industry: Direct Measurements, Chemometric Correlations, and Multiple Spectroscopy Data Fusion

John C. Edwards
Process NMR Associates, LLC, Danbury, CT

For the past two decades high resolution 1H NMR systems combined with chemometric analyses have been utilized in refineries and chemical plants to predict the chemical and physical properties of process streams and finished products. The ability to perform these analyses with on-line NMR instrumentation has allowed tighter control and optimization of the plant to obtain margin improvement, reduced reworking of off-specification materials, and higher yields of finished products. Examples of refinery and petrochemical applications will be given along with some examples of multinuclear NMR applications utilizing 31P and 19F NMR. The permanent magnet based 1.5 Tesla NMR instruments will be described along with a description of how these compact, cryogen-free NMR systems can be utilized on the bench-top or in the fume-hood as continuous or stop-flow chemistry sensors for reaction monitoring, mixing/dilution monitoring, or purity/conversion monitoring. Food applications will also be described such as dairy (butter, cream cheese) and edible or essential oil analysis. Finally, the ability to improve the quality of the correlations derived in the chemometric modelling by "fusing" NMR data with spectral information from other spectroscopies (NIR, Mid-IR) will be discussed.

Poster 1

1H qNMR Determination of Acetylated Polysaccharides, Glucose, Maltodextrin, Isocitrate, Degradation Products, Preservatives and Additives in Aloe Vera Leaf Juice
John C. Edwards
Process NMR Associates, LLC, Danbury, CT

Aloe Vera is a botanical component that is used widely in the cosmetic, natural product, herbal supplement, and pharmaceutical industries. The widespread use of Aloe Vera has lead to the need to adequately analyze the authenticity, quality, and quantity of the various components present in this material. The 1H qNMR method described here was developed and validated by Process NMR Associates for a number of NMR service customers and the method will be included in an upcoming Monograph on Aloe Vera published by the American Herbal Pharmacopoeia. The method can be used for the detection and quantitation of the primary components of interest in Aloe Vera juice products and raw materials for compliance with IASC (International Aloe Science Council) certification requirements, specifically, for determination of the content of acetylated polysaccharides, the presence of glucose, the presence and content of maltodextrin, and the content of isocitrate. Additionally, for meeting quality control specifications beyond IASC requirements, the presence and content of the following groups of compounds can be determined: degradation products (e.g., lactic acid, pyruvic acid, succinic acid, fumaric acid, acetic acid, formic acid, and ethanol), preservatives (e.g., potassium sorbate, sodium benzoate, and citric acid/citrate), and other atypical impurities, additives, or adulterants (e.g., methanol, glycine, glycerol, sucrose, maltodextrin, flavorants (propylene glycol/ethanol)). We will describe a common internal-standard NMR methodology that does not require additional equipment or advanced automation software. The method is applicable to a number of different Aloe Vera raw materials and products, including liquid and dried juices. In aloe vera finished products the method is only applicable when the observable aloe vera constituents are present at a high enough concentration to be observed and are not obscured by additional product ingredients with signals in overlapping areas.

Poster 2

Compact, Cryogen-Free, High-Resolution 60 MHz Permanent Magnet NMR Systems for Reaction Monitoring and On-Line/At-Line Process Control Observing 1H, 19F, 31P

John C. Edwards1, Tal Cohen2, Paul J. Giammatteo1

1. Process NMR Associates, LLC Danbury, CT

2. Aspect AI, Shoham, Israel

A compact high resolution NMR system will be described that can be situated on the bench-top or in the fume hood to be used as a continuous or stop-flow detector and/or an “in-situ” reaction monitoring system. The same system can be fully integrated into on-line shelters for on-line process control or utilized by engineers and technicians in an "at-line" environment. The system uses a unique 1.5 Tesla permanent magnet that can accommodate sample tube diameters of 3-10 mm with half-height spectral resolution (water resonance) approaching 1-3 Hz depending on the sample volume size and with excellent single pulse sensitivity. These systems can be utilized in a traditional NMR methodology approach or combined with chemometric approaches that allow NMR data to predict chemical and physical properties of materials via regression analyses that establish correlations between observed spectral variability and sample-to-sample property variance [1].

1) “Process NMR Spectroscopy: Technology and On-line Applications”, John C. Edwards, and Paul J. Giammatteo, in Process Analytical Technology: Spectroscopic Tools and Implementation Strategies for the Chemical and Pharmaceutical Industries, 2nd Ed.,  Editor Katherine Bakeev, Blackwell-Wiley, 2010

Poster 3

Calculation of Average Molecular Descriptions of Heavy Petroleum Hydrocarbons by Combined Analysis by Quantitative 13C and DEPT-45 NMR Experiments John Edwards Process NMR Associates, LLC, Danbury, CT Abstract
Much debate has centered around the validity and accuracy of NMR measurements to accurately describe the sample chemistry of heavy petroleum materials. Of particular issue has been the calculated size of aromatic ring systems that in general seem to be underestimated in size by NMR methods. This underestimation is principally caused by variance in chemical shift ranges used by researchers to define the aromatic carbon types observed in the 13C NMR spectrum, in particular the bridgehead aromatic carbons that can be shown to overlap strongly with the protonated aromatic carbons. The ability to discern between bridgehead aromatic carbons and protonated carbons in the 108-129.5 ppm region of the spectrum is key in the derivation of molecular parameters that describe the "molecular average" present in the sample. Utilizing methodologies developed by Pugmire and Solum for the solid-state 13C NMR analysis of coals and other carbonaceous solids we have developed a new liquid-state 13C NMR method that allows the relative quantification of overlapping protonated and bridgehead aromatic carbon signals to be determined. The NMR experiments involve the combined analysis of both quantitative 13C single pulse excitation which observes all carbons quantitatively, and a DEPT45 polarization transfer which observes only the protonated carbons in the sample. Though the DEPT45 results are not quantitative across all carbon types (CH, CH2, and CH3) due to polarization transfer differences, the technique is well enough understood that simple multiplication factors allow the relative intensities of the different carbons to be determined. The average ring system sizes derived from these NMR experiments tend to be several ring systems larger than has been calculated in previous studies. In heavy petroleum asphaltenes the average aromatic ring system is 5-7 rings in size which is in agreement with FTICR-MS and fluorescence measurements, rather than the 3-4 rings previously reported.

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