Spectrophotometry

A spectrophotometer is an analytical instrument used to quantitatively measure the transmission or reflection of visible light, UV light or infrared light. Spectrophotometers measure intensity as a function of light source wavelength. There are two classes of spectrophotometers: single and dual beam. Single beam specs measure absolute light intensity and double beam specs measures the ratio of light intensities on two separate light paths--the reference standard and the sample. Type so specs include microplate spectrophotometers, colorimeters, and florescence microplate readers. Spectrophotometers are widely used in various disciplines such as physics, molecular biology, chemistry and biochemistry. Applications for specs include measurement of substance concentration such as protein, DNA or RNA, growth of bacterial cells, and enzymatic reactions. Important features to look for in spectrophotometer are broad dynamic range, sample volume capability and lamp type and lifetime.