By processn, on January 20th, 2012
Process NMR Associates has developed an extension of its 1H NMR analysis of Aloe Vera raw materials and products analysis. Powder aloe vera raw materials (100x/200x) can be analyzed directly and juice samples (1x, 5x, 10x, commercial products) must be freeze dried for this analysis. The whole leaf markers utilized in this test to indicate the presence of whole leaf material are iso-citrate and iso-citrate lactone which are formed in the green leaf part of the aloe plant as part of the citric acid cycle. It is possible to assign and quantify the following components of an aloe vera juice or powder:
* aloe vera components: acemannan, glucose, malic acid
* whole leaf markers: isocitrate, iso-citrate lactone, citric acid
* degradation products: lactic acid, acetic acid, fumaric acid, pyruvic acid, formic acid, succinic acid, and ethanol
* adulterants: maltodextrin
* preservatives: sorbate, benzoate
* additives: sucrose, fructose, flavorants (contain ethanol and propylene glycol)
For the components above it is possible to obtain a wt% of that component in a juice sample – the freeze drying process is then used to determine the wt% solids in the juice and the dry weight concentrations of the organic components in the solids.
Currently testing of aloe vera raw materials revolve around acemannan and whole leaf marker content and the presence of glucose. Process NMR Associates method can perform this analysis but also tell you the “quality” of the aloe vera raw material – the absolute concentrations of degradation products can tell you a lot about the exposure of the raw material to:
* excessive heat (hydrolyzation of acemannan acetyl groups to acetic acid (vinegar) or formic acid)
* lactobacillus bacteria (found on the skin of the aloe vera plant – these bacteria “eat” malic acid and produce lactic acid)
* enzymatic processes (enzymes found in the aloe vera plant itself can cause degradation to succinic acid or fumaric acid
The figure below shows the NMR assignment of a whole leaf juice that has been freeze dried. From the molar ratios of the various 1H NMR peaks it is possible to obtain a wt% value for all components by comparison with a nicotinamide internal standard (spectral range not shown) and the molecular weight of the component molecule or monomer unit.
1H NMR spectroscopy observes signals from all protons in the sample simultaneously. Aloe vera components, preservatives, and degradation products yield peaks at specific chemical shifts which can be integrated and quantified. Observations are made on the following peaks:
Nicotinamide – Internal NMR Standard: 1) 8.85 ppm, 2) 8.2 ppm (often coincides with formic acid), 3) 7.55 ppm, 4) 8.65 ppm
Glucose – C1 proton for alpha conformation at 5.2 ppm (doublet) and C1 proton for beta conformation at 4.6 ppm (doublet)
Malic Acid – CH at 4.35 ppm (multiplet), CH2 at 2.4-2.8 ppm (multiplet)
Acemannan – CH3 resonances of acemannan acetylation – fingerprint distribution of methyl resonances from 2.0-2.2 ppm
Lactic Acid – CH3 Peak at 1.33 ppm (doublet)
Acetic Acid – CH3 peak at 1.92 ppm (singlet)
Succinic Acid – 2 x CH2 peak at 2.5 ppm (singlet)
Formic Acid – Aldehyde Resonance at 8.2 ppm (singlet)
Ethanol – CH3 peak at 1.18 ppm (triplet)
Pyruvic Acid – CH3 peak at 2.35 ppm (singlet)
Citric Acid – 2 x CH2 resonances at 2.4 to 3.0 ppm (multiplet)
Iso-Citrate (Whole Leaf Marker) – CH at 4.25 ppm (doublet)
Iso-Citrate Lactone (Whole Leaf Marker) – CH at 5.05 ppm (doublet)
Benzoate – ortho-protons (2H) give peaks at 7.8 ppm.
Sorbate – CH3 peak is observed at 1.77 ppm (doublet) olefin protons observed at 5.7, 6.15, &7 ppm.
Fumaric Acid – CH peak at 6.55 ppm (singlet)
Sucrose – C1 proton observed at 5.4 ppm (doublet)
Maltodextrin – qNMR protons observed at 5.4 ppm
Maltodextrin is readily observed and quantified by 1H NMR – in the figure below is an example of a 100x and a 200x aloe vera gel powder – the 100x sample contains 50 wt% maltodextrin – the peaks at 5.4 and in the 3.5-4.0 ppm region are used to quantify the presence of maltodextrin.
Process NMR Associates is currently the only company providing a detailed breakdown of the components of aloe vera including quantitation of the whole leaf markers. Dry weight limits of acemannan, whole leaf markers, and maltodextrin are required for aloe vera raw material certification and quality control.
In the food industry it is found that most fruits, beverages, and dairy products contain a complex mixture of these same organic acid chemistry components. 1H NMR has a unique advantage in the analysis of these types of materials as NMR requires very little sample preparation and the data can be used to unequivocally identify the presence of single component chemistries and to quantify their presence in a single 15-30 minute analysis. Process NMR Associates are available to develop NMR based methodologies on any of these types of food systems and would welcome discussion of this with potential customers. Customers are not charged for initial consultation and project scoping. These NMR methods are universally applicable on NMR systems from 200-900 MHz. If you are interested please contact John Edwards (Tel: +1 (203) 744-5905)
By processn, on January 20th, 2012
Talk 1 by John Edwards
Mutivariate Analysis of 1H and 13C NMR Data of Residual Catalytic Cracker Feed-Streams: NMR Pre-Processing Strategies that Allow the Development of Predictive Models of Physical and Chemical Properties that are Independent of NMR Instrument Magnetic Field Strength
John C. Edwards*# and Jincheol Kim†
*Process NMR Associates, LLC, 87A Sand Pit Rd, Danbury, CT 06810 USA
† SK Innovation Co., Ltd, SK Innovation Technology Center, 140-1, Wonchon-dong, Yuseong-gu, Daejeon 305-712, Korea
# Speaker
Historically refinery control engineers are familiar with GC derived chemical properties such as aromatics, benzene, PONA, olefins in wt% or vol%, as well as physical properties such as distillation, viscosity, conradson carbon, sulfur, density, etc. We have developed generally applicable multivariate regression methods that allow many of these familiar chemical and physical properties to be derived from quantitative 1H or 13C NMR data. We have also developed magnetic field independent data manipulation methods that allow 1H or 13C NMR derived parameters to be utilized as the X matrix “spectral” data rather than the spectra themselves. This allows field independent models to be developed as these parameters are calculated from the spectrum and are the same regardless of the magnetic field strength at which the NMR data was collected. This has implications with respect to calibration transfer between laboratories and analyzers. In this work we describe the application of these methods to feed-streams to a residual catalytic cracker (RCC), which represents the core gasoline and diesel production facility in many refineries.
Talk 2 by Paul Giammatteo
Practical Applications of Compact High-Resolution 60 MHz Permanent Magnet NMR Systems for Reaction Monitoring and Online Process Control
John Edwards*, Paul Giammatteo*#, Mark Zell†, and David Foley†
* Process NMR Associates, 87A Sand Pit Rd, Danbury, CT, 06810 USA
† Pfizer Global Research and Development, Groton Laboratories, Eastern Point Road, Groton, CT 06340 USA
# Speaker
Process NMR Associates will be exhibiting the Spin Pulse range of TD-NMR spectrometers as well as the Aspect Italia 60 MHz high resolution NMR system – See us at the Cosa-Xentaur booth in the exhibition.
For more details on IFPAC visit http://www.ifpac.com/
By processn, on January 20th, 2012
CASSS announces the first Practical Applications of NMR Conference 2012. Save the Date: October 15-17, 2012. The conference will be held at the Hyatt Regency Schaumberg, Schaumberg, IL USA. John Edwards has volunteered to serve on the organizing committee and will be developing a session of talks on on-line/at-line NMR and TD-NMR technologies. Other exciting sessions will revolve around other practical NMR applications in industry – more details will be posted when the program has been developed further.
By processn, on January 18th, 2012
Below are a few further examples of acetylation reactions of acetic anhydride with an excess of alcohol. The alcohols include tert-butanol and isopropanol.
Reaction 1: Acetylation of t-butyl alcohol with acetic anhydride in the presence of acid.
Reaction 2: Acetylation of Isopropanol with acetic anhydride in the presence of acid.
Reaction 3: Methoxyacetone and hydroxylamine reaction in methanol to form an Oxime
Resolution of the methylenes in the methoxyacetone and the reaction product is readily observed.
All the above experiments were performed in an NMR tube. We are currently looking at the same reactions under flow conditions utilizing a HPLC pump and PEEK tubing to transport sample to the NMR probe at 5 ml/min.
By processn, on January 3rd, 2012
Modcon Systems (Israel) introduces the MOD-8000, a new generation of Nuclei Magnetic Resonance (NMR) process analyser. A new concept in the design of the magnet, the electronics and the software was implemented, alongside a suitable sampling system. High reliability and accuracy is achieved by eliminating sensitivity towards any temperature fluctuations.
Process streams with different temperatures and flow properties can accurately be analysed by one single instrument.
NMR is a fundamental method; it is based on the assignment and/or quantification of the chemical components and functionalities that are present in a refinery or petrochemical process stream. The linear spectral response enables chemometric methods to quantify accurately the required physical and chemical properties of process streams.
In contrast to optical correlative methods, its accuracy is not influenced by the presence of substances with atoms others than hydrogen and carbon which vary according to the origin of crude oils. Crude switching will not have any impact on the analytical results.
The MOD-8000 NMR process analyser is applicable to transparent, dense and opaque solutions alike. On-line analyses of crude oil, the entire range of distillates, and a variety of refinery streams, providing a highly effective tool in meeting the challenges of ongoing process optimisation and control.
Further Details
Application Possibilities
For details on the MOD-8000 NMR analyzer contact Paul Giammatteo – Tel: +1 (203) 744-5905
By processn, on January 2nd, 2012
Below is an example of a 19F NMR Spectrum obtained at 54.6 MHz on a 1.4 Tesla permanent magnet-based NMR System.
This is a 2 minute spectrum obtained by co-averaging 16 FIDs after zero-fill, autophase, referencing of each individual FID. The NMR system is not locked. No apodization of the NMR FID data was performed.
For more details on potential applications of 19F NMR please contact John Edwards (Tel: +1 203-744-5905)
By processn, on January 2nd, 2012
New Flash: Chevron purchases high resolution 31P NMR system for at-line analysis of a phosphoric acid catalyzed alkylation process.
The Chevron Richmond Refinery needed a simple and quick measurement of phosphoric acid strength and quality. Prior analysis procedures included transporting samples several miles from the refinery process to the technical center in order to perform the 31P NMR analysis on a high field superconducting NMR system. This process was also complicated by the fact that the process operators were not able to perform the analyses on the conventional high field NMR systems (400 MHz for 1H, 161 MHz for 31P) themselves, but had to wait for NMR technician and instrument availability. If sample analyses was required after research facility working hours the NMR lab technicians were required to come in and run the NMR for the process operators.
A simple permanent magnet bench-top NMR system has now been placed in the existing process lab adjacent to the process unit control room. The NMR samples are placed in specially designed 9 mm (diameter) x 50 mm (length) sample tubes in order to accommodate sample handling issues (high viscosity sample with no solvents being added) and are place easily into the NMR probe. Sample preparation is essentially non-existent and sample waste is minimal. The 31P NMR analysis itself takes around 3 minutes to perform.
The “at-line” NMR system is a high resolution Qualion permanent magnet system operating at 58.3 MHz for 1H and 24.2 MHz for 31P. The system is located on a lab bench in the process lab building. Some examples of the system performance are shown along with the comparison with high field NMR results. It can be seen that the lower field instrument provides more than adequate resolution to perform the acid strength analysis.
Figure 1: 31P NMR of 85% Phosphoric Acid
Figures 1 and 2 show quantitative 31P NMR spectra of different phosphoric acid concentrations dissolved in water. The NMR analysis is found to be fully quantitative.
Figure 2: 31P NMR signal acquired at 24.2 MHz on several concentrations of phosphoric acid in water.
Figure 3 shows the 31P NMR data obtained at 7 Tesla (121 MHz) and 1.4 Tesla (24.2 MHz) of actual process samples. The peak at 0 ppm corresponds to orthophosphoric acid, the peak at -15 ppm corresponds to the terminal P atoms of a polyphosphoric acid chain, and the peak at -30 ppm corresponds to internal P atoms in the middle of polyphosphoric acid chains. Relative areas of these peaks are used to calculate the acid strength.
Figure 3: High field and low field 31P NMR spectra of Used Phosphoric Acid from Alkylation Process
Figure 4: 31P NMR spectra and calculated acid strengths obtained on 3 different used phosphoric acid samples
Figure 5: Another comparison of 7 Tesla laboratory acquired NMR data compared to rapid at-line 1.4 Tesla NMR assay of phosphoric acid strength.
The NMR system being utilized at the Chevron Richmond refinery is a Qualion 60 MHz NMR system utilizing a 31P probe.
For further details or to discuss your own NMR applications please contact Paul Giammatteo (Tel: +1 203-744-5905)
By processn, on December 27th, 2011
Jonathan Chui has a nice site with chemistry illustrations – here is an overview of 1H NMR Interpretation … Resolution-Independent PDF
By processn, on December 21st, 2011
John Edwards, principal of Process NMR Associates has authored a chapter entitled “A Review of Applications of NMR Spectroscopy in the Petroleum Industry” which appears in a new ASTM publication: Monograph 9 – Spectroscopic Analysis of Petroleum Products and Lubricants, Edited by Kishore Nadkarni. The chapter describes the application of high resolution 1H and 13C NMR, 1H TD-NMR, and solid-state NMR to petroleum chemistry and refining.
The book can be ordered at the ASTM Bookstore.
By processn, on August 3rd, 2011
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