Analytical Chemistry

Measure Twice

What is spectrophotometry?

Spectrophotometry is a technique that involves passing light through a sample to measure the fraction of light transmitted or reflected by the sample. This can be useful for determining the concentration of an analyte in a solution or for determining the identity of an analyte present.

A law known as Beer’s law (see also “Physical and Theoretical Chemistry”) is particularly important in spectrophotometry. Beer’s law tells us that the concentration of a species is directly proportional to its absorbance in a solution. This means that if we know the absorbance of a solution of our analyte at a known concentration, we can determine the concentration of that analyte in any other solution.


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