The FAST CAT® Green (deoxy) Chloramphenicol Acetyl Assay Kit contains a substrate that greatly simplifies the quantitation of chloramphenicol acetyltransferases (CAT) activity. In this kit, the original FAST CAT® substrate has been modified to produce a reagent that undergoes a single acetylation reaction, yielding only one fluorescent product. To use, after a suitable incubation period, the product and remaining substrate are extracted and separated by thin-layer chromatography (TLC). The bright fluorescent, well-resolved spots can be immediately visualized with a hand-held UV lamp or quantitated with a laser scanner or CCD camera.