Abstract: [Objective] To evaluate the uncertainty of determination of lactoferrin content in pasteurized milk by high performance liquid chromatography.[Method] According to the “CNAS—GL006—2019 Guidelines for Evaluation of Uncertainty in Chemical Analysis”and“GB 5009.299—2024 National Food Safety Standard for Determination of Lactoferrin in Food”,the content of lactoferrin in pasteurized milk was determined by high performance liquid chromatography. Established a mathematical model to identify the main sources of uncertainty introduced during the experiment,then quantified them,synthesized standard uncertainty,and calculated extended uncertainty.[Result] When the mass concentration of lactoferrin in pasteurized milk was 4.17 mg/100 g,the extended uncertainty of the result was 0.16 mg/100 g,including factor k=2,with a confidence probability of 95%.[Conclusion] The main sources of uncertainty introduced during the experiment included repeated measurements（u1）,calibration curve fitting（u2）,preparation of standard solution series（u3）,constant volume of samples（u4）,and weighing of samples（u5）. The measurement uncertainty components have a significant impact on the detection results.The uncertainty of the evaluation criteria can standardize the experimental operation process in a targeted manner,reduce the impact of introduced uncertainty components on the detection results,provide a scientific basis for quality control of lactoferrin detection,and is also one of the necessary conditions for the laboratory to be accredited by the China National Accreditation Service for Conformity Assessment（CNAS）.

Key words: lactoferrin, high performance liquid chromatography method, pasteurized milk, uncertainty