Chromatographic Nuclear Magnetic Resonance Technique And Its Application

Chromatographic nuclear magnetic resonance(CNMR)technique could achieve the analysis of componants in the mixture without chromatogaphic separation.This technology has made great progress in analysis of mixture components,e.g.biomass conversion and drug identification.At present,there is still relatively less work on improving the effect of separation of CNMR.Therefore,in this work,the effect of organic solvent on the separation of CNMR was studied.In addition,the practical application of CNMR technique was investigated in this work.First of all,four kinds of organic modifiers such as deuterated methanol,deuterated dimethyl sulfoxide,deuterated acetone and deuterated acetonitrile were used in this work.The compounds of different types such as alcohol,acid and amino acid were used as model mixtures.The effect of organic modifiers with different volume fractions on the separation of CNMR was studied.As shown in the experimental results,the effects of the first three deuterium reagents on the separation of analytes were similar.With the increase of the volume fraction of deuterated reagent in the aqueous phase,diffusion coefficients of the analytes decreased firstly and then increased.However,the diffusion coefficients of the analytes continued to increase with the increase of the volume fraction of deuterated acetonitrile.To some extent,the addition of the deuterium reagent improved the separation effect of the mixtures analytes.Secondly,the sodium dodecyl sulfonate was used as a virtual stationary phase,the separation capacity of the following six groups of aromatic organic acid mixture was investigated as following:(1)o-hydroxybenzoic acid,m-hydroxybenzoic acid and p-hydroxybenzoic acid;(2)benzoic acid,phthalic acid and trimesic acid;(3)salicylic acid,phthalic acid and p-toluenesulfonic acid;(4)salicylic acid,p-bromobenzoic acid and p-toluenesulfonic acid;(5)benzoic acid,phthalic acid and p-toluenesulfonic acid;(6)benzoic acid,p-bromobenzoic acid and p-toluenesulfonic acid.The experimental results showed that the above six groups could achieve signal separation under the action of virtual stationary phase.The reason for the signal separation may be that the effects of the virtual stationary phase on the analyte are difference.Finally,this technique was also applied to determine the actual fermentation broth of succinic acid.The main composition of the fermentation broth was identified by measuring the diffusion coefficient of different components in the fermentation broth,reffering to the nuclear magnetic signal of the model compound.It was found that the main substances contained in the fermentation broth were glucose,succinic acid and acetic acid.Moreover,the composition of the practical mixture sample was further quantitatively determined by qHNMR technique,which was consisted with the HPLC experimental result.