Hepatitis B test kit

The sample is placed in contact with an anti-HBs monoclonal antibody immobilized onto a solid support. If it contains the HBsAg antigen, it will form a complex with the antibodies and will bind to the support. The unbound fraction is eliminated by washing, after which another anti-HBs monoclonal antibody conjugated to peroxidase is added. If a reaction was produced during the first stage of the process, the conjugate will bind. After a new wash the enzymatic substrate is added. If HBsAg is present in the sample, a light blue color is developed. The reaction is stopped by adding sulfuric acid, which makes the light blue color change to yellow.