The HBsAg Rapid Test a rapid, direct binding test for the visual detection of hepatitis B surface antigen (HBsAg) in serum/plasma. It is used as an aid in the diagnosis of hepatitis B infection. One Step HBsAg RapidCard InstaTest is based on the principle of sandwich immunoassay for determination of HBsAg in serum/plasma. Monoclonal and polyclonal antibodies are employed to identify HBsAg specifically. This one step test is very sensitive and only takes about 10-20 minutes. Test results are read visually without any instrument.