IR in the Liquid Phase and Neat Samples

Salt plates are used to take an IR spectra of a liquid sample. The plates work the same way as the potassium bromide for solid samples. The major problem of using a liquid sample is choosing a solvent with which to dilute the sample. The list below shows the areas that the solvents are usable (Carbon disulfide is usable around 2500 cm^-1 and then after 1250 cm^-1, etc.).

No solvent is perfect but if some information about the compound is known, then a solvent can be chosen accordingly. Notice that water is not a solvent on this list. First, water is a bad solvent because it will dissolve the salt plates. Second, water exibits a broad -OH peak that will cover up a lot of other peaks that you are interested in. These two reasons are good enough to NEVER USE WATER WHEN TAKING AN IR.