Colorimetric testing is an analytical technique that is what one might guess it is: a chemical reaction that produces a visible color change. So the idea is that a sample chemical interacts with another chemical, called a reagent, and if the sample chemical happens to be the target of the reagent, then a color is produced. The color could be identified by a human eye or by a machine eye (camera or colorimeter). Colorimetric testing has been around for a long time with much of the seminal work in the field being done as far back as the nineteenth century; much of the work was related to developing dyes for the booming fabric industry. Since then, with new synthesis techniques and with new materials, Field Forensics has developed several colorimetric test kits for a range of target analytes such as tests for virtually all explosives and narcotics as well as metals and even biological substances. Colorimetric tests can identify classes of chemical compounds or identify individual chemicals. An understanding of what a particular colorimetric test is meant to react with is essential to properly detecting and/or identifying explosives, narcotics, and other chemical compounds of interest. Field Forensics offers several product lines including ELITE™, IDEX™, ULTRA™, DABIT™ and BioScreener™, which are all one-use disposable test kits relying on the human eye to see the expected color change; the ELITE.Guard™ is a handheld instrument, which automatically detects and discerns color changes on a chemical swab.