Use of a Laser-equipped Centrifugal Analyzer for Kinetic Measurement of Serum lgG

Use of a visible laser in an Aminco “Rotochem” centrifugal analyzer enables light-scattering measurements to be made with this instrument. The modification is technically simple, inexpensive, and requires no fundamental changes in basic instrument design. The laser-modified analyzer has been applied to the measurement of lgG in serum. A two-point kinetic analysis is used to quantitate lgG from a standard curve: protein concentration vs. change in intensity of the scattered light during a fixed time interval. Fourteen 20-tI samples can be simultaneously determined in 1.9 mm. No sample blank corrections are required. Within-run precision studies, based in each case on 56 replicate measurements, yielded coefficients of variation of 3.8 % and 4.8 % for normal and abnormal pools, respectively.