Sensitive immunochemical approaches for quantitative (FPIA) and qualitative (lateral flow tests) determination of gentamicin in milk

Publication date: 1 March 2016
Source:Talanta, Volume 149
Author(s): N.V. Beloglazova, P.S. Shmelin, S.A. Eremin
Three kinds of immunoassays for the determination of gentamicin in milk samples were developed and validated. First, a fast and easily-performed fluorescence polarization immunoassay was used for characterization of the employed polyclonal antibody. The calculated Kaff were (1.9±0.4)×10⁹М⁻¹ and (6.0±0.2)×10⁶М⁻¹ for the high- and low-affinity fractions respectively. The assay was characterized with a good sensitivity, the limit of detection being 5μgkg⁻¹. Two different kinds of detection labels, i.e. colloidal gold (CG) and quantum dots (QDs), were evaluated for use in lateral-flow format with respect to rapid visual on-site testing. The cut-off levels for both qualitative formats were selected based on the maximum level for gentamicin in milk established by the European Commission, 100μgkg⁻¹, resulting in a 10μgkg⁻¹ cut-off considering sample dilution. The intra-laboratory validation was performed with sterilized milk samples artificially spiked with gentamicin at concentrations less than, equal to, and greater than the cut-off level. It was shown that milk products could be analyzed without any sample preparation, except for dilution with the buffer solution. The rates of false-positive and false-negative results were below 5% for both labels. The different developed immunoassays were tested towards gentamicin determination in artificially-spiked and naturally contaminated milk samples.

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