The Hepatitis B Surface Antibody (HBsAb) test is a rapid chromatographic immunoassay for the qualitative detection of Hepatitis B Surface Antibody in serum or plasma. The HBsAg Rapid Test Cassette is a lateral flow chromatographic immunoassay for the qualitative detection of Hepatitis B surface antigen (HBsAg) in human whole blood, serum or plasma.