Experiment on determination of ethanol chemical shift and concentration of ethanol solution based on nuclear magnetic resonance instrument

Xinyi Liang,X Wei

doi:10.1051/e3sconf/202021301026

Abstract

In this designing experiment, a nuclear magnetic resonance instrument was used to study the chemical shift properties of ethanol based on the principle of magnetic shielding effect. At the same time, the nuclear magnetic resonance method was used to study the transverse relaxation time and signal strength of ethanol aqueous solution in the range of 5%to 40%. The relationship between different mass fraction of ethanol-aqueous solution and nuclear magnetic resonance signal intensity, relaxation time and solution concentration were analysed. According to the results, due to the limitation of experimental instruments, no regular changes were observed. The results show that the addition of copper sulphate can increase the ethanol content and the effect of the ethanol content on the lateral relaxation time: the ethanol content varies between 5% and 40%, and the lateral relaxation time changes from 8.42ms to 40.35ms.According to the experimental results, the empirical formulas of the concentration and lateral relaxation time of ethanol aqueous solution with fixed amount of copper sulphate were fitted. Using this relationship, the NMR measurement of the concentration of ethanol-water solution can be achieved, which provides a new method for the convenient and accurate measurement of the concentration of ethanol solution.

Highlights

Nuclear magnetic resonance (NMR) (Nuclear Magnetic Resonance, NMR) spectroscopy is a very rapidly developing science, and a modern technology that can penetrate into the material without destroying the structure of the measured object
As in the analysis of Experiment 11, due to the special nature of CuSO4, the increase in the ethanol content in the ethanol aqueous solution will combine with the hydrogen bond of the water, which will inhibit the amplification of the local magnetic field of the hydrogen nucleus of the copper ion by the copper ion, so the signal intensity decreases with increasing ethanol content
Because the resolution of the NMR instrument is greater than the chemical shift of ethanol, the expected three peaks of ethanol are not measured

Summary

Introduction

NMR (Nuclear Magnetic Resonance, NMR) spectroscopy is a very rapidly developing science, and a modern technology that can penetrate into the material without destroying the structure of the measured object. Ghanghas et al [10] outlined a simple procedure that uses proton nuclear magnetic resonance spectroscopy to establish the hydrogen bond geometry in liquid ethanol, and distinguishes the methyl group of CH3CH2OH by using the difference in the proton chemical shift value generated by the secondary isotope effect The line of deuterated CH3CD2OH in the 1H NMR spectrum of the mixture of both and hydroxyl protons. An interesting finding emerging from the study is that the linear relationship between the distance and angle of hydrogen bonding in ethanol This experiment successfully revealed to the experimenter the principles of pulsed nuclear magnetic resonance and its relaxation time and chemical shift. The ingenious application of the amplification effect of copper ions (Cu2+) on the local magnetic field to study the ethanol aqueous solution effectively reduced the sample T2 and improved the The feasibility of detecting the content of ethanol aqueous solution in low field nuclear magnetic resonance technology.[11]

Experimental Section

Experimental samples

Test Results and Discussions

Conclusion