Friday, 30 July 2010

New Fast NMR technique

Instrument time is precious and a plethora of different fast NMR experiments are continuously being proposed in order to reduce the time required to record an NMR spectrum. Actually, money is not the only reason, there are many other factors which motivate the development of techniques to increase the speed of data collection. For example, if one wants to make real-time studies of kinetic processes or protein folding, it’s pivotal to speed up the acquisition of NMR data, in particular multidimensional spectra.
On this issue, we have just put our bit into this field and published an article which describes the use of localized spectroscopy for parallel multidimensional NMR data acquisition. The key idea is to interleave the data acquisition at a variety of localized bands within a given interscan repetition time.

In other words, the method is based on MRI-type slice selection techniques (e.g. spinecho multislice and gradient echo multislice) where nuclear spins in different parts of the tube are excited and detected during subsequent transients while the previously used spins have time to relax towards equilibrium before being excited again, hence achieving a considerable timesaving in the overall acquisition.
We believe that this method; named PALSY, is a very powerful yet simple and general technique to reduce experimental time. Of course, there is a sensitivity penalty approximately proportional to the number of slices chosen, but the good thing is that the achievable resolution in any dimension is not compromised in any way.
Another point of interest is that it does not require any fancy data processing, just a simple data shuffling operation needed to extract the different sub-spectra contained into the acquired raw data matrix. This operation has been implemented into the Mnova Alpha version and will be available in the next official release. Meanwhile, as always, should anyone be interested in evaluating this alpha version, just drop a comment here and I will get in touch to provide an executable.
The article can be accessed here:

Fast multidimensional localized parallel NMR spectroscopy for the analysis of samples

I would like to take this opportunity to acknowledge and congratulate my friend Manolo for this work. He is the intellectual father of this pulse sequence and is currently extending this idea further to cover other NMR experiments.

1 comment:

Sebastian P. said...

Great post! I have often wondered about the time benefits of selective aquisition, didn't stop to think it could be done in parallel though.

I am unsure if this has already been done, or can be adapted using this technique, but assuming one has obtained a 1H spectrum which has a large quantity of 'dead space' (ie some aromatic protons and some aliphatics, but 6-4ppm unpopulated), would it be fairly easy to perform a selective nD analysis only on these regions? in a manner where each aquisition region is unique in size/inhomogenous? (as arguably any signals outside those regions are probably artifacts).

Rather than taking hours for ghMBCs, even with a healthy 'buffer zone' around 1H and 13C to account for drift, we could be looking at time savings of 80% or upwards if we previously aquired 1H and 13C spectra and know 'where we are looking for signals'.