Chemistry

Absorbance of Light vs. Concentration of Colored Solution Introduction: Performing this lab showed the importance of light in virtual drug screening because light can be used in a variety of ways to obtain different kinds of information in research. Light can be used to determine the concentration of DNA or protein in solution, tag different objects such as cells, protein structures, or bacteria in order to determine whether there is a large amount of a certain substance, and to determine the size of different particles. One main use for light in virtual drug screening is high throughput screening, which allows the researcher to do multiple numbers of tests on substances and quickly identify them. For example, a researcher can use light scattering to screen for ligands by measuring the amount of light scattered. The scattered light can be used to determine if there is an aggregation of proteins and how stable those proteins are, which informs researchers whether there is a ligand binding to the protein or not1. However, the point of this lab was to show how light can be used to determine the concentrations of either DNA or proteins in solution, which is a very important part of virtual drug screening. This lab introduced how a spectrophotometer can be used to determine the absorbance of different concentrations of a certain solution, and then how to use the information gathered and Beer‟s Law to calculate the concentration of an unknown solution. Beer‟s Law relates the length which light has to travel through the solution, the concentration of the solution, and the molar absorptivity with the absorbance of that solution. Beer‟s Law states that “there is a logarithmic dependence between the transmission of light that shines through a material and the density of the material as well as the length of the material that the light is traveling through”2. The logarithmic relationship is important to this lab because at high concentrations, absorbance is no longer directly