A method of evaluating an asphaltene inhibitor includes providing a centrifugal microfluidic system including: a disc mounted to rotate about an axis; a microfluidic device mounted on the disc, the device having sample, solvent, inhibitor, and precipitant reservoirs and an analysis chamber in fluid communication with the sample, solvent, inhibitor, and precipitant reservoirs; and an optical detection system coupled to the analysis chamber and configured to measure the optical transmission of fluid in the analysis chamber. The method includes filling the sample, solvent, inhibitor, and precipitant reservoirs, respectively, with a sample, solvent, inhibitor, and precipitant; rotating the disc to generate centrifugal force to cause the sample, solvent, inhibitor, and precipitant to travel radially outward to the analysis chamber; and measuring the optical transmission of a mixture of the sample, solvent, inhibitor, and precipitant in the analysis chamber as a function of radial distance of the analysis chamber.