Detection of Immunoglobulin G Content in Milk Powder by High Performance Liquid Chromatography

A high performance liquid chromatography (HPLC) method for the detection of immunoglobulin G (IgG) in milk powder was established by studying the effects of immunoaffinity column performance, temperature of the sample solution during immunoaffinity column cleanup, and the type of eluent on the detection of the IgG content in milk powder. Samples were extracted with phosphate buffer solution, and the extract was purified by immunoaffinity column chromatography. The eluate was separated on a C₄ reversed-phase column (250 mm × 4.6 mm, 3.5 μm), detected using HPLC-ultraviolet detector, and quantified by an external standard method. The results showed that the method was applicable to milk powder with different IgG contents. The standard curve exhibited good linearity in the concentration range of 10-500 μg/mL. The detection limit of the method was 80 mg/kg, and the quantification limit was 300 mg/kg. The recoveries and precision expressed as relative standard deviations (RSDs) at three spiked levels (300, 600 and 3000 mg/kg) were both aligned with the requirements of the Chinese national food safety standard GB 5009.295-2023. This method is simple, efficient and accurate, providing precise technical support for the evaluation of the nutritional value of new functional dairy products and product claims.