Absorption Spectrum

The characteristic absorption peaks of a compound at various wavelengths of light, e.g., guanine has maximal absorption at about 278 nm at pH 9 but its maximum at pH 6.8 is at ca. 245 nm ultraviolet light; chlorophyll-a has an absorption maximum in benzene at ca. 680 and 420 nm visible light, whereas chlorophyll-b maxima are at ca. 660 and 460 nm, respectively. These characteristics vary according to the pH and the solvents used and are determined by spectrophotometers.