Absorbance-based detection can be performed on the PHERAstar® FSX, CLARIOstar®, FLUOstar®, SPECTROstar® and POLARstar® Omega plate readers, as well as on the dedicated SPECTROstar Nano. A high-power xenon flash lamp illuminates the sample using a specific wavelength selected by an optical filter. In the case of most BMG LABTECH microplate readers, a UV/Vis spectrometer is used instead of filters to collect the entire spectrum instead of a specific wavelength. BMG LABTECH’s spectrometer captures all wavelengths from 220 to 1000nm at a resolution of 1 – 10 nm in less than 1 second per well. Absorbance microplate readers
Absorbance, also known as Optical Density (OD), is defined as the (logarithmic) ratio between the intensity of light hitting a sample and the intensity of that very light transmitted through the sample. While a specific wavelength of light selected by a filter illuminates a sample, part of this light gets absorbed. The non-absorbed light passes through the sample and is collected by a detector located opposite the light source, on the other side of the microplate well.
Since the amount of light absorbed by a sample relates to its concentration (Lambert-Beer law), absorbance has been used for the quantification of nucleic acids and proteins as well as in popular colorimetric reactions such as ELISA tests. BMG LABTECH offers a variety of absorbance microplate readers.
The following are examples of absorbance measurements takes on BMG LABTECH microplate readers:
- AN 169: Old Assays, New Instrument: ELISA; NADH and NADPH Conversion; DNA and Protein Quantitation
- AN 226: A New Way to Test the Free Amino Nitrogen Content in Alcoholic Beverages with the SPECTROstar Nano
- AN 242: Low-volume protein measurements (280nm): Validating the LVis Plate over many concentrations
See a complete list of absorbance application notes.
The following plate readers can be configured to perform absorbance measurements.