Instruments may be used to identify compounds, or perform qualitative analysis. Some of the same instruments also may be used to measure the % of a desired constituent with proper standards and methods.

Metal ions in solution are may be analyzed both quantitatively and qualitatively with atomic absorption or inductively coupled plasma. Wavelength of absorptions identify the ions at the same time that the size of the absorption can be used to measure the concentration of each ion.

Infrared spectroscopy measures the energy absorbed by rotations and vibrations which are characteristic of molecules. Infrared spectroscopy is extensively used for qualitative analysis of organic compounds. Preparing samples reproducibly is such a problem with this technique that it is seldom used for quantitative analysis.

Chromatography may be used for sorting out compounds by retention times. These retention times may be used to identify compounds if appropriate standards are available.

In mass spectrometry, molecules are broken into ions by bombardment. These ion fragmentation patterns are characteristic of specific groups of atoms. By carefully measuring the mass to charge ratio of each ion, the analyst using a computer can quickly identify specific groups to determine the molecule containing all of these overlapping fractions.