EXPT 2 ABSTRACT Spectrophotometry is the measurement of light waves. It uses the spectrophotometer as its instrument, which are classified based on the light it uses. Ultraviolet (UV) having the shortest wavelength (< 300nm), visible (vis) (300 nm-700 nm), and infrared (> 1000 nm), and combination UV-vis, UV-vis-IR are the most commonly used in spectrophotometer. Absorption of visible light by different solutions with red, blue, yellow, green, violet and orange food color and absorption of ultraviolet light by 0.1% glucose, ribose, PA, adenosine, cytosine, Gly, Arg, Tyr, Phe, and BSA are measured in this experiment. Relationship between concentration and absorption were also determined using 0.1 M CuSO4. Objectives of this experiment include the determination of the optimal wavelength of light from primary and secondary colored solutions, the identification of the macromolecules responsible in UV absorption, and the generation of a standard curve to determine the concentrations of solutions. Optimum absorbance of red, orange, yellow, green, blue, and violet colored solution were observed at 500, 475, 425, 425, 625, and 300 nm, respectively. Glucose, ribose, PA, adenosine, cytosine, Gly, Arg, Tyr, Phe, and BSA showed optimum wavelength at 250 nm except for Gly, which shows at 225 nm.