the test , which uses 50 microliter sample of blood , plasma or serum , is done in a capillary tube and , by comparison with two adjacent reference tubes containing standardised sera , places immunity to tetanus in one of three categories -- low-negative ( less than 0.01 iu/ml ) , intermediate ( 0.01-1.28 iu/ml ) or high ( greater than 1.28 iu/ml ) .
C0032105
plasma
C0229671
sera