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Lowry's method was based on the Folin-Ciocalteu “Phenol Reagent” method of protein determination (1). Lowry determined that the Folin-Cioalteu phenol reagent (phosphomolybdic-phosphotungstic acid) would readily bind to proteins treated with copper. The bound reagent was reduced over time, resulting in a color change from yellow to blue, which could then be used to determine protein concentration using a spectrophotometer, such as a microplate reader.
The Lowry assay is easily done on any BMG LABTECH microplate reader that has absorbance capabilities.