Abstract: [Objective] To evaluate the uncertainty of the SNAP dual-flow enzyme-linked immunosorbent assay (ELISA) for determining the antibiotic content in raw milk. [Methods] Using a three-in-one test strip, antibiotics such as β-lactam, tetracycline, and cephalexin in raw milk were measured. The sources of uncertainty were analyzed, and a complete mathematical model was established. Each component in the model was analyzed and evaluated. The relative standard uncertainty was synthesized and expanded to obtain the expanded uncertainty of the antibiotic measurements for β-lactam, tetracycline, and cephalexin in raw milk samples. [Results] When the confidence level was 95%, the results of the antibiotic measurements in raw milk were: X(β-lactam) = 0.64±0.173 8, with k=2, and the expanded uncertainty was U=0.173 8. X(tetracycline) = 0.62±0.168 4, with k=2, and the expanded uncertainty was U=0.168 4. X(cephalexin) = 0.37±0.100 4, with k=2, and the expanded uncertainty was U=0.100 4 mg/kg. [Conclusion] The uncertainty in the experimental process mainly originates from sample repeatability, sampling volume, test strip reader, and result calculation. This method can provide a reference for evaluating the uncertainty of the SNAP dual-flow ELISA for determining antibiotic levels in raw milk.

Key words: SNAP two-flow enzyme immunoassay, raw milk, antibiotics, determination, uncertainty