Use of the ultracentrifuge vertical rotor in the detection of rubella-specific IgM on a sucrose density gradient.

A comparison was made of the performance of swing-out and vertical ultracentrifuge rotors in the detection of rubella-specific IgM on a sucrose density gradient. Tests were performed on 30 sera, of which 11 were found to contain rubella-specific IgM by both methods. The centrifugation time for the swing-out rotor was 16 hours at 35,000 rpm. This was reduced to 2 hours using the vertical rotor at 50,000 rpm. Routine use of the vertical rotor would allow a reduction in the time taken to perform the test, increase the number of sera tested each time, and reduce wear on the ultracentrifuge.