Automatic phase correction of 2D NMR spectra by a whitening method

Abstract

A new method for the automatic phase correction of multidimensional NMR spectra is described. It is based on the whitening concept formulated as the 'maximization of the number of white pixels into a bitmap that corresponds to the spectrum'. This process of maximization can be factorized along the individual axes of the spectrum and this property makes the method robust and fast. It employs a statistic measure based on a large number of spectral data points and, for this reason, is very tolerant to low signal-to-noise ratio (SNR) and local artifacts. The algorithm can efficiently phase either homonuclear or heteronuclear experiments and, unlike other previous methods, it can also process automatically spectra containing positive or negative peaks so that it is not necessary to deal with individual or special cases

Physical methods and techniques NMR spectroscopy

“…The algorithm can efficiently phase either homonuclear or heteronuclear experiments and, unlike other previous methods, it can also automatically process spectra containing positive or negative signals. 98 Density functional theory calculations (DFT) of the chemical shifts for polycyclic aromatic hydrocarbons (benzene, naphthalene, anthracene, naphthacene, pentacene) applying a recently developed theory of orbital magnetisation in solids, and a method where the shifts are obtained from the derivative of the orbital magnetisation with respect to the localised magnetic dipole, gave good agreement with experiments. 99 Computationally derived 13 C NMR chemical shifts of different types of carbon nanotubes may guide experimental characterisation; diameter distribution, the Knight shift of metallic tubes, and the induced chemical shifts of small molecules encapsulated in nanotubes have been calculated.…”

Quantitative NMR Studies of Multiple Compound Mixtures

“…For quantitative purpose, prior to Fourier transform, the time-domain data need to be zero-filled to give at least five datapoints above the half height for each resonance to allow for precise and reliable integration [23]. The Fourier transformed spectra can then be phased manually or automatically [24], polynomial baseline correction can be applied to improve the accuracy of the integral.…”