Bio-Rad's protein assay is a simple colorimetric assay for measuring total protein concentration. The standard assay is used with samples having protein concentrations between 200 µg/ml and 1,400 µg/ml (20–140 µg total). The microassay is used with samples having concentrations <25 µg/ml (1–20 µg total). The assay has also been automated for rapid determinations in 96-well microplates.BIORAD .