A modified quantitative precipitin test which is rapid, sensitive and reproducible.

A modification of the standard quantitative precipitin test is described. The new procedure, which utilizes polyethylene glycol (PEG) at both the 37 degrees C and 4 degrees C incubation stages, provides a convenient quantitative precipitin test assay which is more reliable and much faster than the standard assay. Moreover, the modified or PEG assay gives a quantitative measure of antibody concentration even when antisera of low titre are tested. The sensitivity of the capillary-tube test is also enhanced when the supernatant solutions contain PEG.