Similarly, detergents or surfactants, particularly nonionic detergents, such as those of octoxynol (e.g., sold under the trademark Triton X of Rohm & Haas, such as Triton X-100) might be included, typically as remnants, carried into a solution used in an assay according to the invention, of a solution used to lyse cells from which luciferase is extracted for the assay.