Description
In order to dissociate IGF-I from the IGFBPs, the samples must be diluted in an acidic buffer (Sample Buffer PP). The diluted samples are then pipetted into the assay wells. The IGF-I antiserum is dissolved in a buffer, which is able to neutralize the acidic samples. After the IGF-I antibody solution has neutralized the samples, the present excess IGF-II occupies the IGF-binding sites of the binding proteins, thus allowing the measurement of the resulting free IGF-I. With this method, the IGFBPs are not removed, but their function and therefore their interference in the assay is neutralized. Due to the extremely low cross-reactivity of the IGF-I antibody with IGF-II, the excess of IGF-II does not disturb the interaction of the first antibody with IGF-I