Phase Modulated Selective NMR Methods for resolving overlapping spin systems and rapid data acquisition : Application in metabolomics
research work is focused on the development of new fast solution NMR methods for resolving overlapping spin systems and their application to NMR based metabolomics. In this work two new solution NMR pulse sequences are developed by combining the phase modulation and selective excitation strategy. In addition, a new technique dubbed as in-silico spiking is introduced for assisting in the assignment of phase modulated selective spectra. The application of these methods on diverse samples are also demonstrated. a new technique for rapid assignment of a set of PM 1D - selective TOCSY spectra. This is essential for the assignment of real metabolic samples since, there will be a large number of spectra recorded for this propose. Unlike the physical spiking the in-silico spiking technique introduced in this study assist in the assignment process without alternating the metabolic sample. The application of PM 1D - selective TOCSY and the in-silico spiking technique is demonstrated on a real sample namely, the one step media used for growing human embryos in in-vitro fertilisation (IVF) procedure. The knowledge about the metabolites present in the growth medium is essential to identify biomarkers that can serve as potential indicators of the quality of the embryos for the transplantation and hence the chance for success of the IVF procedure. Using the new methods, we were able to identify and assign 20 reported metabolites and three new spin systems/metabolites (one assigned and two unidentified). These metabolites can be used as leads in identifying biomarkers which can help in predicting the success rate of IVF procedures.