What is absorbance measured in?
Absorbance is measured using a spectrophotometer or microplate reader, which is an instrument that shines light of a specified wavelength through a sample and measures the amount of light that the sample absorbs.
Spectrophotometer vs. Plate Reader
A standard spectrophotometer measures absorbance one sample at a time, typically placed in a cuvette through which light is sent horizontally. An absorbance plate reader offers higher throughput and can measure the absorbance of samples in microplates, usually 96-well or even 384-well, by sending light through each well vertically.