Chloride Channel Assay Kit (Colorimetric) provides a sensitive and robust colorimetric method for studying chloride channels. The assay is based on our proprietary iodide indicator (Iodide Sensor Blue dye) to measure iodide concentration, as low as 30 nM of iodide can be detected. Iodide Sensor Blue dye forms a blue complex with iodide, which has absorption spanning from the UV to 700 nm. Thus a few absorption wavelengths can be used for monitoring the iodide-dependent color change. Chloride Channel Assay Kit (Colorimetric) provides an optimized assay method for monitoring chloride channels. The assay can be performed in a convenient 96-well or 384-well microtiter-plate format.