Nuclear Magnetic Resonance (NMR) spectroscopy is a very useful tool in chemistry to analyze the structure and composition of molecules. For scientists in the chemical domain, NMR is not a stranger. It has become a must have tool for chemistry, biochemistry, pharmacy and other research. The analysis of the structures of many small molecule compounds, peptides, proteins, etc., all rely heavily on NMR, including one-dimensional (1D), 2D and 3D NMR.

In NMR experiments, samples are often dissolved in deuterated solvents to minimize the solvent signal interference. But even very small amounts of leftover protonated solvents can throw off the NMR spectrum, and cause misleading results.

In NMR analysis, the chemical shift of solvents and their impurities is an important tool for identifying and analyzing the structure of compounds. This is why Alfa Chemistry gives you a point of reference for the chemical shifts of common solvent impurities in NMR spectra to help you analyze and detect signals in NMR spectra more precisely and more accurately, to streamline and increase the accuracy of chemical analysis and project development.

Selection criteria for NMR solvents

Choosing the correct NMR solvent involves meticulous consideration of various factors. These include the chemical shift range and miscibility with the analyte, stability, volatility, purity, non-toxicity, and cost. Furthermore, solvent peak recognition is essential to distinguish the solvent signal from the sample signals, aiding in spectral analysis.

An ideal NMR solvent should have the following characteristics:

Chemical Stability

NMR solvents should be chemically stable, meaning they do not react with the samples or other reagents used in the experiment. This ensures that the solvent does not interfere with the NMR signals or alter the chemical nature of the sample.

High Purity

The purity of NMR solvents is preferably higher than 99.9% to ensure accurate and reliable NMR spectra. Impurities can interfere with the NMR signal and cause incorrect interpretation of spectra.

Low Viscosity

NMR solvents with low viscosity ensure good sample rotation and optimal data acquisition. High viscosity solvents can cause problems with sample homogeneity and can lead to NMR peak broadening.

Good Solubility

NMR solvents should have good solubility for a wide range of compounds. This allows for the analysis of different types of samples, including polar and non-polar compounds.

Broad Chemical Shift Range

NMR solvents should have a broad chemical shift range to cover a wide range of chemical species. This is important for accurately determining the chemical shifts of different nuclei in the sample.

Stability Under NMR Conditions

NMR solvents should be stable under the conditions of the NMR experiment, including temperature, magnetic field strength, and exposure to air and moisture. This ensures that the solvent remains unchanged throughout the experiment.

Lack of Interfering Signals

NMR solvents should not have any interfering NMR signals that overlap with the signals of interest in the sample. This can be achieved by using deuterated solvents, which do not give rise to NMR signals in the same frequency range as protons or other nuclei commonly analyzed in NMR experiments.

Low Toxicity

NMR solvents should have low toxicity to ensure the safety of the users. This is especially important since NMR solvents are often handled in large quantities and can come into contact with skin or be inhaled during experiments.