Lab #5: UV-Vis and Fluorescence Introduction:Ultraviolet-visible spectroscopy (UV-VIS) refers to absorption spectroscopy or reflectance spectroscopy in the ultraviolet-visible spectral region. It uses light in the visible and adjacent range in which the reflectance directly affects the perceived color of the chemicals involved. UV-Vis spectroscopy is routinely used in analytical chemistry for the quantitative determination of different analytes, such as transition metal ions, highly conjugated organic compounds, and biological macromolecules. Analysis is commonly carried out in solutions but solids and gases may also be studied. Fluorescence spectroscopy is a type of electromagnetic spectroscopy which analyzes fluorescence form a sample. It involves using a beam of light (usually ultraviolet) to excite electrons in molecules of certain compounds. This causes them to emit light typically in visible light. In a typical experiment, the different wavelengths of fluorescent light emitted by a sample are measure using a monochromator, holding the excitation light at a constant wavelength called an emission spectrum. Purpose:UV-Vis:The purpose of this lab is to determine the absorbance levels of Salicylic Acid in aged aspirin samples by running sample of SA in hexanes through the UV-Vis instrument. Fluorescence:The purpose of the next part in the lab is to determine the amount of quinine in tonic water through the fluorescence instruments. Procedure:UV-Vis:1.Turn on instrument (switch located at the rear left)2.Turn on computer and double click on Vision Pro Software on the Desktop3.Allow the instrument to initialize for 10-15 minutes4.In the toolbar frame, select the scan icon a.