Materials that are commonly analyzed include nucleic acids like DNA and RNA and protein solutions. It is more specific than the term electromagnetic spectroscopy in that it deals with different wavelengths, such as x-ray, visible light, ultraviolet, near-ultraviolet, infrared, and near-infrared. It’s essential to understand the distinction between these wavelengths of light, as they play an important part in how a spectrophotometer can be used. And knowing how a spectrophotometer operates will help you optimize your work.

Spectrophotometry uses photometers (referrred to as spectrophotometers) to measure a light beam’s intensity as a function of its color (wavelength). Important features of these instruments are spectral bandwidth (the range of colors it can transmit through the test sample), the percentage of sample transmission, the logarithmic range of sample absorption, and sometimes a percentage of reflectance measurement.

A standard spectrophotometer’s uses include the measurement of transmittance or reflectance in solutions and solids. These models measure gases as well. However, spectrophotometers are also designed to measure the diffusivity on any of the listed light ranges that cover around 200 nm – 2500 nm, using different controls and calibrations.

Within these ranges of light, calibrations are needed on the machine using standards that vary in type depending on the wavelength of the photometric determination.

An example of an experiment in which spectrophotometry is used is the determination of the equilibrium constant of a solution. A certain chemical reaction within a solution may occur in a forward and reverse direction where reactants form products and products break down into reactants.

At some point, this chemical reaction will reach a point of balance called an equilibrium point. To determine the respective concentrations of reactants and products at this point, the light transmittance of the solution can be tested using spectrophotometry.

In other words, researchers can observe how much light is absorbed by measuring the intensity of light the sample emits as the light passes through the sample solution. This is indicative of the concentration of certain chemicals in the solution that do not allow light to pass through.