Cholesterol is an essential molecule found in all animals and is a structural component of animal cell membranes. It is the reason why animal cells are flexible and animals can move, unlike plant cells which have rigid cell walls. Cholesterol is a sterol and the cells in your body synthesize about 1 gram every day.
With recent advances in the performance of benchtop NMR, such as the 80 MHz Spinsolve 80, it is interesting to see the 13C NMR spectra from molecules such as Cholesterol. With a molecular weight of 386 g/mol and 27 carbon atoms it is a larger molecule than is typical measured on a Carbon-13 capable benchtop NMR spectrometer. Because there are more peaks to resolve, both the sensitivity and resolution of the instrument are tested with this measurement.
The 1D proton-decoupled 13C NMR spectrum of a 400 mM sample of Cholesterol measured by a Spinsolve 80 is shown in the figure below. Because 13C has a lower gyromagnetic ratio than protons, the 13C Larmor frequency is 20 MHz. The region between 20 ppm and 45 ppm has been expanded to show how the carbon peaks are resolved.
We are really excited to introduce the newest Spinsolve benchtop NMR – the 80MHz Spinsolve 80. Spinsolve 80 combines industry leading resolution (0.5 Hz/20 Hz) and the highest sensitivity and chemical shift dispersion with an unparalleled 80 MHz magnet at its core. All Spinsolve benchtop NMR systems include easy to use software, convenient size and weight, and superior stability to give you quick and convenient NMR spectroscopy, wherever you want it.
To download a brochure and learn more please click on the image below
If you have any other questions about Spinsolve 80, or any of our products, please contact us.
Our development team is constantly working on improving performance of the Spinsolve. And as a result the quality of NMR spectra you can obtain with Spinsolve has continued to improve. To show this, we have been updating the NMR spectral examples that are available on this website, and also updating Spinsolve 60 MHz data. So please go to Example NMR Spectra and browse through the page. Hope you find these examples useful!
Did you miss our recent webinar ? No problem, just click the red button below to stream a replay of the webinar held on 27th October 2016: Thinking Outside the (Benchtop) Box – High-Field NMR Techniques on Benchtop Instruments
In this webinar you will learn about:
High-field techniques that are now possible on benchtop instruments.
Applications and problems solved by advancements in benchtop NMR spectroscopy.
The size, ease-of-use, and economic advantages of benchtop instruments over high-field machines.
In recent years benchtop NMR spectrometers have become an increasingly viable alternative to high-field systems. Many demanding resolution and sensitivity requirements can now be met with modern methods and instruments. In this webinar we illustrate how a number of well-established and modern high-field NMR techniques, such as 2D, non-uniform sampling (NUS), and pure shift experiments, can be implemented on a benchtop NMR system to solve problems and applications previously considered beyond reach.
Quantification using any analytical method requires calibrating an instrumental response with a known reference, and then calculating the concentration of an unknown sample from the measured instrument response. One advantage of NMR compared to other analytical methods is that the signal response is linear, resulting the NMR signal intensity being proportional to the number of nuclei.
Sample concentrations and purities can be easily measured from known peaks once the proportionality constant is calibrated using a reference of known concentration and purity. Such measurement methods are known as quantitative NMR, or qNMR for short.
We regularly post testimonials on our blog, where our customers describe how they are using their Spinsolve and comment on their experience using it. We have a number of these user stories now, so we have conveniently compiled them all on a new page ‘Testimonials‘.
Take a look to see how Spinsolve users all over the world, in teaching and research, are using their Spinsolves.
Dr Peter Keizers is a scientist in the Centre for Health Protection at RIVM, the Dutch National Institute for Public Health and the Environment based in Bilthoven. As a chemist, he investigates (illegal) drugs, medical devices and other medicinal products. His group studies the composition of these products and specifically look for active pharmaceutical ingredients, preferably in a quantitative way.
Thrilled to announce the launch of the NEW Spinsolve ULTRA Benchtop NMR system. The Spinsolve ULTRA has the field homogeneity of a superconducting NMR magnet (0.2 Hz / 6 Hz / 12 Hz) in a compact and robust benchtop unit.
When combined with solvent suppression it allows users to resolve compounds dissolved at sub-millimolar concentrations in protonated solvents, such as water. The example below shows how effective the suppression of the very large water signal is. This enables metabolites at concentrations down to a few hundred micromolars to be detected in an 8 minute measurement.
Please contact us to discuss if Spinsolve ULTRA is useful for your application.
Dr Leena Kaisalo heads up the Organic Chemistry student laboratory at the University of Helsinki. While the Laboratory’s research focuses on organic synthesis, Dr Kaisalo’s role is to lead the teaching of bachelor and masters students in various analytical techniques including NMR.
Dr Leena Kaisalo uses her Magritek Spinsolve Benchtop NMR Spectrometer at the University of Helsinki Chemistry Department
Despite the proliferation of new 2D techniques over the past four decades, one of the most commonly used experiments is the very first one to have come into existence, COSY1. It’s easy to see why it’s withstood the test of time: firstly, it’s an extremely useful experiment, providing a direct and easy way of establishing “through bond” proton-proton connectivities (“this hydrogen is near or next to that hydrogen”); secondly, because it’s a homonuclear 2D experiment (that is to say, it correlates protons with protons) its’s a very sensitive one. The high sensitivity also means that it’s a quick experiment to run, particularly if the experiment uses gradients for coherence selection (more on that below and in a future blog post).
Example COSY spectra recorded on Spinsolve can be found elsewhere on the Magritek website, but a typical example is also shown in Figure 1 below, recorded on a sample of ethyl crotonate. The sequence used to collect this spectrum utilizes gradients, meaning that it was run using only a single scan per t1 increment, and with 512 increments it only took 15 minutes to run.
Fig. 1. COSY spectrum of ethyl crotonate, collected using gradients and 512 t1 increments.
One of the advanced features of the Spinsolve 80 is the ability to run a Multiplicity Edited HSQC, also known as HSQC-ME. This powerful 2D NMR sequence has proton in the horizontal (f2) axis and carbon in the vertical (f1) axis. The peaks appear where a proton is connected to a carbon atom. Additional information about “multiplicity” is given by the sign of the peak, just like in a DEPT experiment. Positive peaks (red) are either CH or CH3, while negative peaks (blue) are from CH2. This additional information really helps with correct peak assignment.
The example below is from an HSQC-ME experiment run on a sample of Quinine and shows all the peaks uniquely resolved and assigned.
The Spinsolve is not only a perfect tool to teach NMR to Chemistry students, but its performance enables it to be used for serious research. This is evidenced in the published papers from our users. Over the last few months there has been a number of new publications featuring Spinsolve. In this post we will highlight a few of them. Click here for a full comprehensive list of publications.
Dr Jeroen Geuens is a member of the Centre of Expertise on Sustainable Chemistry (CESC) based in Antwerp at the Karel de Grote University College. The Centre specialises in research and services related to chemical and production processes together with offering professional degree courses.
Before discovering the Spinsolve benchtop NMR from Magritek they could only get access to NMR measurements by taking their samples to the University of Antwerp. The Spinsolve is now used continuously for both teaching and research in the CESC. Dr Geuens takes up the story.
In an earlier post on qNMR we described how benchtop NMR can be used to quantify the concentration of a sample or measure its purity. When such quantitative methods are validated, there are standard requirements for accuracy, precision, range, and linearity over that range that need to be met.
For example, the United States Pharmacopeia (USP) specifies the general requirements for a Category I NMR method when measuring a drug substance (there are other specifications for finished products and impurities). These specifications are listed in the table at the end of this post and are compared to the measured Spinsolve performance.
We have validated the Spinsolve benchtop qNMR performance by measuring the purity of one reference standard, methylsulfonylmethane (MSM), with another, maleic acid. Maleic acid is a common reference standard for qNMR, so this was used as the reference to measure the known purity of MSM (specified 99.5% pure). A spectrum of the mixture in D2O is shown in Figure 1.
HTBLA Wels is a higher technical vocational college of chemistry in Austria. Here, Dr Harald Baumgartner is responsible for the instrumental analytical laboratory. The lab’s main focus is to teach students the basics of NMR (interpretation of spectra).
Dr Baumgartner says “Compared to the old 60 MHz spectrometer, the Magritek Spinsolve benchtop spectrometer is so much easier to use. It is software-based so collecting and processing data is quite straightforward. As well as 1H spectra, our Spinsolve allows us to measure more complex spectra including 13C-spectra. Even 2-dimensional experiments are now available to the students.”
A college student learns about NMR with the Magritek Spinsolve Carbon at HTLBA Wels in Austria