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Title: how can I calculate specific absorbance? Post by: kondzia on Jan 12, 2015 Hi guys!
I've got a problem. I'm not sure how to calculate specific absorbance. My data: -Absorbance 1 -Absorbance2 -Protein concentration -Nacl -Standard protein Title: Re: how can I calculate specific absorbance? Post by: habiba on Jan 13, 2015 The proportionality approach to these kinds of problems focuses on the idea that the absorbance of a solution is directly proportional to its concentration. When using this approach it is necessary to be sure that the values given are for different concentrations of the same chemical measured under the SAME conditions (BOTH wavelength and the path length).
Question: A solution with a concentration of 0.14M is measured to have an absorbance of 0.43. Another solution of the same chemical is measured under the same conditions and has an absorbance of 0.37. What is its concentration? The solution to this problem can be set up using the equation shown below, which simply says that the ratio of the concentrations is proportional to the ratio of absorbances. We can use c1 to represent the unknown concentration. You can derive this equation from Beer's law (Absorbance = e L c) C1 / C2 = A1 / A2 (ONLY for absorbances that are measured/predicted at the SAME Wavelength) Therefore, C1 = (A1 / A2) * C2 Substitute all the values as follow: A1 = 0.37; A2= 0.43 & C2=0.14M Thus, C1 = 0.12M |