Detection of antibiotics in milk

Abstract

A method for detecting the presence of antibiotics in milk which comprises the steps of: (a) contacting a solid matrix having attached thereto a purified immobilized antibody with a volume of milk and an enzyme-labeled antibiotic, said antibody being specific to said antibiotic; (b) separating the matrix from the milk and rinsing the matrix with water to remove excess milk and enzyme-labeled antibiotic; (c) contacting the rinsed matrix with a substrate, said substrate in the presence of said enzyme-labeled antibiotic exhibiting a color change the amount of which is quantitatively related to the amount of enzyme-labeled antibiotic; and (d) measuring the amount of antibiotic present in said milk by comparing the color change in said substrate with a standard. Also provided is a method for producing purified antibodies for use in the foregoing detection method by: (a) convalently conjugating an antibiotic having a lactam-ring in the molecule to a protein capable of binding thereto through said lactam-ring; (b) injecting into a host animal capable of raising antibodies specific to said antibiotic the conjugate obtained in step (a) so as to raise said specific antibodies; (c) covalently conjugating the same antibiotic in step (a) to a second protein capable of binding thereto through said lactam-ring and different than the protein used in step (a) to form a second conjugate; (d) covalently binding said second conjugate to a solid matrix to form an affinity matrix for purifying the antibodies; (e) isolating and purifying the specific antibodies raised in step (b) by contacting the host animal serum with the affinity matrix; and (f) recovering the specific antibodies in pure form.