Spectrophotometers measure light intensity as a function of wavelength and are commonly used to measure the concentration of a compound in an aqueous solution. Depending on the type of spectrophotometer, different wavelengths of light can be analyzed. UV-Vis spectrophotometers (ultraviolet visible) measure in the UV and visible regions of the electromagnetic spectrum (190 to 380 nm and 380 to 760 nm, respectively).