BioChain's chloride assay kit is a simple, direct and automation-ready assay for measuring chloride concentration in biological samples without pretreatment. The improved Fried method utilizes mercuric 2,4,6-tripyridyl-s-triazine, which forms a colored complex specifically with chloride. The intensity of the color is directly proportional to the chloride concentration in the sample. The optimized formulation substantially reduces interference by substances in the raw samples.