Cry9C protein in StarLink (SL) corn is an endotoxin produced from a gene derived from Bacillus thuringiensis (Bt). This method is a quantitative enzyme linked immunosorbent assay (ELISA) determination of Cry9C protein, utilizing proprietary antibodies, from EnviroLogix, Inc. The method is calibrated to estimate the weight percent of modified corn in corn flour and corn meal.