The patented multichannel optical design of the SpectraMax® 190 Absorbance Microplate Reader mimics a dual beam spectrophotometer, measures each sample in the plate directly, and eliminates measurement error due to variations in light output between optical fibers on other instruments for more reliable data reporting. The eight-channel system delivers both high precision and speed when reading 96-well microplates for endpoint measurements, kinetic assays, and spectral scans. The optical system of the SpectraMax 190 Microplate Reader is built around a monochromator, which allows for selection of up to six wavelengths at a time for absorbance detection in the UV-visible wavelength range (190 nm - 850 nm). Narrow bandwidths deliver increased measurement accuracy and linearity over the widest range of assays, including DNA quantitation in the UV range. Using the patented PathCheck® Pathlength Measurement Technology, the SpectraMax 190 Microplate Reader transforms each well in a microplate to a fixed optical pathlength cuvette. This temperature-independent normalization corrects for varying well volumes and can eliminate standard curves by allowing the calculation of concentrations directly from the absorbance with a known extinction coefficient, as exemplified with nucleic acid and protein quantitation.