Enzyme immunoassay of hepatitis B surface antigen with use of the "Hepanostika" test kit and a new photometer, "Photo-Elisa 1".

We describe an enzyme immunoassay for hepatitis B surface antigen, with use of a Hepanostika test kit and "Photo-Elisa 1," a photometer capable of measuring small quantities of test material. Because the length of the optical path in the "Photo-Elisa 1" is only 1.2 mm, volumes as small as 15 micro L can be can be measured. Accuracy is enhanced through cancellation of background absorbance by measurement at two wavelengths. Results obtained with the kit compare well with those by radioimmunoassay. By substituting photometric reading for visual reading, Hepanostika provides a more nearly accurate screening test.