A competitive immunoassay based on gold nanoparticles for the detection of chromium in water samples

Abstract

A competitive enzyme-linked immunosorbent assay (ELISA) based on colloidal gold nanoparticles modified with a monoclonal antibody and horseradish peroxidase (HRP) was developed and validated for the quantitative determination of chromium in water samples. The monoclonal antibody against Cr(III)–EDTA secreted by the hybridoma cell line 5G12C5 was prepared through cell fusion. The ELISA conditions were optimized using the chessboard method and the sensitivity and specificity of this assay were determined. The results show that this competitive immunoassay has a half maximum inhibition concentration (IC50) of 3.85 ng mL⁻¹ and a limit of detection (LOD) of 0.1 ng mL⁻¹. Specificity assays revealed that the cross-reactivities (CRs) of this assay with 10 other common metal ions were all below 1%. The accuracy of this immunoassay was confirmed by using certified reference materials (GSBZ50027-94, GSB07-1187-2000). Furthermore, the assay was used to detect the concentrations of Cr(VI) and total chromium in local surface water samples after the pretreatment procedure. The data show that the results of this method correlated well with those obtained from atomic absorption spectroscopy (AAS) (R² = 0.9728), and that this method is capable of detecting the amount of total chromium and Cr(VI).