An antibody specific to the Cry1F protein molecule is immobilized on the microwell plates and second antibody specific for Cry1F molecule is conjugated with horse radish peroxidase (HRP). When the sample extracts are added to the microtiter wells, the Cry1F from sample binds to the antibody immobilized in the well. This binding is subsequently detected by the addition of the enzyme-labeled antibody. After a washing step, the substrate is added. The enzymatic reaction and development of color are proportional to the amount of Cry1F present in the sample. The reaction is terminated by the addition of stop solution. Absorbance is measured on a plate reader.