Snap swabs are moistened with a buffer that aids in the removal of any biological material (ATP) on either wet or dry surfaces, while also penetrating through any biofilm to expose underlying cells. The ATP from microbiological cells, in addition to free ATP from any food residue, is collected from the sample surface with the swab, and is then available to react with the unique liquid-stable reagent contained in the device. This reagent is derived from a naturally-occurring enzyme (called luciferase) found in fireflies. When this enzyme reacts with ATP on the swab, a low-level of light is produced that can be detected and quantified by the luminometer. The amount of light detected is directly proportional to the amount of ATP on the sample, thus giving a quantitative measure of the cleanliness of the surface where the sample was taken.