60 MHz NMR of Essential Oils from Benchtop System – Comparison to 300 MHz NMR Data

A comparison of the non-spinning 60 MHz NMR data compared with that obtained on a superconducting 300 MHz system are shown below for 10 Essential Oils – those essential oils are: Copaibo Balsam, Dill Weed, Citronella, Parsely Seed, Cinnamon Leaf, Balsam (Peru), Ginger, Eucalyptus Globulus, Petitgrain, Vetiver.



















We currently have a database of 1H (60 and 300 MHz) and 13C NMR data of around 110 essential oils.
For further details on NMR analysis of essential oils please contact John Edwards

Chevron Installs Low Field NMR Application: 31P NMR Analysis of Phosphoric Acid Strength in Alkylation Process

News 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)

Whole Leaf Marker and Maltodextrin in Aloe Vera Raw Materials – Dry Weight Quantity – Extended 1H NMR Analysis Method

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, glycine, 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)

Cryogen-Free NMR – High Resolution Permanent Magnet Systems – The Market Hots Up

It is interesting times in the world of NMR – there are a number of new permanent magnet NMR systems hitting the market. I have seen a number of announcements appearing on LinkedIn and other sites in recent days and then there was a question asked about Cryogen-free NMR systems on the AMMRL server. There is a little confusion out there about who is doing what and what these newer NMR systems are capable of. We (Process NMR Associates and Aspect Italia) have been in the market with a high resolution 60 MHz system (3, 5, or 10mm sample tube) since 1997. Anasazi Instruments have been quitely selling hundreds of 60 and 90 MHz FT-NMR systems based on refurbished or newly manufactured Varian EM-360 and EM-390. New to the scene and making a splash with their marketing campaigns are Picospin (300 micron sample tube, 45 Mhz), Nanalysis (3, 5mm sample tube, 60 MHz). Finally, there is a system from Magritek/ACT (5mm sample tube, 42.5 MHz) that has been re-packaged and is now out there in the world. These systems all produce spectra and can be used in the traditional manner that current supercon systems are utilized. Time-Domain (TD) NMR systems should not be confused with these platforms – TD-NMR spectrometer manufacturers include Cosa-Xentaur, Bruker, Oxford Instruments, SpinLock, MR-Resources – which are used typically for hydrogen content, rheology, simple phase measurements (solid fat, water in oil, oil in water, porosity measurements utilizing relaxation analysis.

For the past 17 years we have been actively developing applications for permanent magnet systems shimmed to approximately 3 Hz at peak half height. The current magnet technology is in its third generation of development and the magnets are built by Aspect Italia and subsidiary of Aspect Imaging who are making an impact with their industrial and clinical MRI systems (Aspect is also working in collaboration with Bruker on their Icon MRI system). The new magnet design is robust and readily shims to 1-2 Hz at half height using 5 or 3 mm NMR tubes. 3 Hz at half height is possible for 10 mm NMR tubes. In the past the focus was in on-line applications in refining and petrochemical and lab systems were not actively marketed. With the third generation of NMR instrument it is time for these robust, non-cryogen, permanent magnet systems to be applied in laboratory and general quality testing applications.

In our laboratory we have an application development advantage in that we have high field 300 MHz NMR systems that are active in commercial NMR analysis and in high field method development. We also have ESR, FTIR-ATR, GC, moisture measurements, and other instruments that we can bring to bear on applications. We can readily develop 60 MHz applications using the 300 MHz NMR data as the basis set to provide primary parameters for analysis or to answer questions about the spectral overlaps that inevitably occur in 60 MHz data sets where 1 ppm on the spectrum axis represents only 60 Hz rather than 300 Hz. When a high field NMR spectroscopist observes a data comparison of spectra obtained at 60 MHz to the same spectrum obtained at 300 MHz (a resolution that most are familiar with) the penny suddenly drops concerning the possibilities that exist for NMR analysis at this field and an appreciation for the work that was performed for the first 30 years of NMR technology on 40 and 60 MHz CW NMR’s. We have become accustomed to our big supercon magnets and have forgotten what can be accomplished at 60 MHz. In these days of powerful computers for multivariate analysis and the ability ot perform global spectral deconvolution (GSD) the ability to develop killer-apps for bench-top, at-line, or in-line applications of 1H/31P/19F/23Na/11B NMR for 110V powered systems is here. The application of chemometrics and GSD at 60 MHz can allow the lower resolution issue of peak overlap to be overcome.

In the past few days I have been “playing around” with the two Aspect systems we have in our lab – comparing spectra obtained on our 300 MHz systems to the same samples on the 60 Mhz systems. Direct comparisons of the data make you realize that though the resolution isn’t anywhere near the same – the information is present in the 60 MHz spectrum. In the links below I have included a number of PDFs showing comparisons of complex essential oil spectra, fish oil and vegetable oils (looking at omega-3 fatty acid content), polyurethane adhesive polymers, shale oil, gasoline and a spectrum of Poloxamer which is a oxyethylene-oxypropylene copolymer utilized in the pharmaceutical industry that has an NMR based USP/NF method associated with it to determine the oxyethylene content.

Polyurethane Polymers – 60 MHz vs 300 MHz – PDF
Essential Oils – 60 MHz vs 300 MHz – PDF
Fish Oils and Seed Oils – Omega-3 Content – 60 MHz vs 300 MHz – PDF
Poloxamer Analysis – Shale Oil and Gasoline Analysis – 60 MHz vs 300 MHz – PDF




Process NMR is actively involved in development of NMR applications utilizing 60 MHz or 300 MHz NMR data. We can develop applications for you and also provide the robust, proven instrumentation that can make affordable, cryogen-free NMR analysis a common automated laboratory tool. We are also looking to prove the utility of this excellent technology in all industrial sectors – if you have an application and would like to see a feasibility study we would be happy to provide such an opportunity. We have NMR systems looking for things to do! Please contact us if you feel you have an application where NMR may provide an answer through direct measurement or chemometric calibration. We are also interested in developing multi-spectroscopy technique data fusion applications where NMR and IR are combined to provide “better answers”.

The Power of MestReNova Data Processing and Analysis Applied to 60 MHz 1H NMR Real Time Reaction Monitoring

The data analysis capabilities of the MestReNova NMR software makes processing and analyzing complex reaction mixture data a snap! Stacked plots are quick and easy and the integration routines rapidly process the peak areas into reaction profiles. Further steps allow the exponential fitting of the reaction profiles to yield kinetic information. Here are a few examples of the data visualization and rapid reaction profiling on a 60 MHz 1H NMR series obtained every 10 seconds (1 pulse) over the course of 25 minutes – the reaction is the esterification of tert-butanol with acetic anhydride in the presence of acid.



Figure 1: Stacked Plot of the Aliphatic Region of the Spectrum with Reaction Chemistry Protons Identified


Figure 2: Stacked Plot – Full Spectrum – Reaction Monitoring – 146 Spectra – 10 Seconds Apart

Figure 3: Angled Stack Plot – Acetic Anhydride and tert-Butanol – Real Time Reaction Monitoring by 1H NMR at 60 MHz

Figure 4: Stacked and Whitewashed Plot of 1H NMR data at 60 MHz – Real Time Reaction Monitoring of Acetic Anhydride with tert-Butanol




Figure 5: Data Analysis Tool and production of reaction profiles.

The MNova data analysis tools allow the user to integrate NMR reaction peaks and automatically plots and fits them to exponential time constants allowing detailed kinetics to be extracted rapidly and easily from the data. What used to take hours of lining up ascii spectra in excel or other software now literally takes seconds. The integration is segmented in such a manner that integrals can be made to track with shifting resonances, for example labile protons effected by pH.

The AspectItalia 60 MHz NMR system allows real time analysis of reactions with high S/N on single pulses. half height linewidths of 1-2 Hz (15-30 ppb) are possible on static reaction setups and 2-5 Hz (30 – 80 ppb) are possible with flowing reactions at rates of 1-20 ml/min.