A simple user-friendly, solid phase radioimmunoassay for testosterone in human serum based on magnetic particles is described.
IgG fractions precipitated from polyclonal testosterone antiserum were coupled to magnetizable cellulose particles using carbonyl
diimidazole. The prepared antibody solid phase was stable for one year when stored at 4 °C. The optimized assay involves the
incubation of 50 ml of testosterone standards (0.3-10 ng/ml), 100 ml of magnetizable cellulose particle coupled antibody suspension
and 100 ml of 125I-testosterone derivative for 4 hours at 37 °C. At the end of the incubation, the tubes were placed on a magnetic rack for
10 minutes after the addition of wash buffer and decanted. The sensitivity of the assay is 0.2 ng/ml. The intra-assay variation
was <15% throughout the assay range. The recovery varied from 88 to 115%. On dilution of samples having high levels of testosterone,
linearity ranged between 87 and 125%. Correlation coefficient of 0.978 was obtained when the developed solid phase assay was
compared to the earlier established liquid phase assay.