Development of indirect competitive enzyme-linked immunoassay of colistin for milk and egg analysis

ABSTRACT

Polyclonal antibodies were obtained by immunizing rabbits with polymyxin B (PMB) conjugated to bovine serum albumin. Based on the heterologous coating conjugate of PMB with periodate-oxidized gelatin and the resulting antibodies, an indirect competitive enzyme-linked immunosorbent assay (ELISA) was developed to detect residual colistin (COL), a structural analogue of PMB in livestock products. The developed analysis was characterized by close specificity towards PMB (100%) and COL (88%), sensitivity (IC₅₀ = 5.7 ng/mL), dynamic range (IC₂₀-IC₈₀ = 1.0–80 ng/mL) and the detection limit of COL (IC₁₀ = 0.4 ng/mL). It was possible to quantify the antibiotic in milk and eggs without special and labour-intensive sample pretreatment using a simple 10- and 50-fold dilution of the corresponding samples. The developed analysis system made it possible to record the maximum residue limit of COL in dairy products (50 μg/kg) and eggs (300 μg/kg) with 89–104% recovery of analyte.

KEYWORDS:

• Colistin
• polymyxin B
• ELISA
• milk
• eggs

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work is financially supported by the grant of the Ministry of Education and Science of the Russian Federation, unique project identifier RFMEFI60417X0198.