A reliable immunoturbidimetry method for immunoglobulin G in bovine colostrum

With rabbit anti-bovine IgG, a reliable, highly selective and cheap method has been optimised and established for the determination of IgG in bovine colostrum. The method was based on the soluble immune complex precipitating from the liquid in the function of polyethylene glycol. Subsequently, the interference of casein, beta-lactglobulin, alpha-lactalbumin, lactofemin and inactive IgG to the immunoassay was investigated. Finally, the assay was applied to the analysis of IgG in spiked milk samples. The limit of detection, calculated as three times of determinations' standard deviation, was 0.07 mg/mL, with a practical working range between 0.2 and 0.8 mg/mL. The average recoveries of IgG in milk were 97.63%, 99.87%, 100.1% for 0.2 mg/mL, 0.5 mg/mL, 0.8 mg/mL, respectively. Eventually, confirmation test between immunoturbidimetry method and high performance liquid chromatography (HPLC) was carried out, and the results of the immunoassay were in accordance with that of HPLC.