A surrogate analytical sample that either has no analyte present or is subject to only part of the analytical process. The purpose of the blank is to assess the contribution of nonspecific effects on the final reaction, and thus be able to eliminate those effects from the final analytical results. The term “blank” may be modified by a word indicating the type of effect being evaluated, with the resultant complete term being, for example, “reagent blank,” a blank containing only reagents.