A NEW IMMUNONANOGOLD GRAPHITE FURNACE ATOMIC ABSORPTION SPECTRAL ASSAY FOR HUMAN CHORIONIC GONADOTROPHIN

Nanogold in the size of 10 nm was used to label rabbit-anti-human chorionic gonadotropin (RHCG) to obtain an immunonanogold probe (AuRHCG) for human chorionic gonadotropin (HCG). In pH 5.2 citric acid-Na(2)HPO(4) buffer solution and in the presence of polyethylene glycol 10000 (PEG 10000), HCG reacted with AuRHCG to form an AuRHCG-HCG immunocomplex that can be removed by centrifuging; AuRHCG in the supernatant was measured by graphite furnace atomic absorption spectrometry (GFAAS). The results showed that the gold absorption value at 242.8 nm decreased as the concentration of HCG increased, and the decreased value was linear to HCG in the range of 0.2-10 mu g/mL, with a detection limit of 0.05 mu g/mL HCG. The new immunonanogold GFAAS assay was applied to determination of HCG in serum samples, with satisfactory results.