[Urbanium]

Hi,

I was taught a long time ago that the solutions which are not perfectly clear should be filtered before NMR acquisition. In what case do the solid particles contribute to bad spectrum? Does the presence of precipitate lower the S/N ratio or it has to do with something else?

What happens in the case when I get a rather stable emulsion when I try to precipitate something with ether? Does the emulsion produce the simillar effect as presence of solid particles?

[snorkack]

Hi,

I was taught a long time ago that the solutions which are not perfectly clear should be filtered before NMR acquisition. In what case do the solid particles contribute to bad spectrum? Does the presence of precipitate lower the S/N ratio or it has to do with something else?

In a solid, single crystal the nuclei might give a clear NMR spectrum. But in polycrystalline or amorphous solid, the atoms have very different local environment, so the lines of the solid are spread into wide low bumps.

What happens in the case when I get a rather stable emulsion when I try to precipitate something with ether? Does the emulsion produce the simillar effect as presence of solid particles?

It should not. Liquids and gases give clear spectra because the atoms move around between different positions in the environment, which they cannot do in solids. Since the droplets in emulsion are liquid, the NMR shifts should also average out.
The third environment in an emulsion should be the surface of droplets, also in an appreciable amount compared to others.