Trichloracetic acid is used in protein concentration determination by quantitative precipitation and as a decalcifier and fixative in microscopy. BioGnost’s Trichloracetic acid, solution is primarily used with the Fouchet-Van Gieson kit. Fouchet-Van Gieson kit is used for simultaneous visualization of bilirubin and collagen in histological samples. Bilirubin is a yellow-brown pigment created as a result of hemoglobin degradation. Hemoglobin degradation occurs in bone marrow, spleen, and liver. In case of patients that suffer from hepatitis, bilirubin builds up in the form of thrombus in bile ducts and in the form of granules in hepatocytes and in the cytoplasm of Kupffer cells. The pigment is insoluble in water and in water fixatives. However, in case of prolonged exposure to formalin fixatives, it may turn green. The color that is created during staining using the Fouchet-Van Gieson kit is due to the strong redox reaction of the complex and subsequent conversion to biliverdin (green). The false-positive reaction may be checked using HemoGnost Perls kit – in that case, Perls’ reaction will always be negative to bilirubin.