Enzyme immunoassay for the quantitative determination of Streptomycin in food.
Background: Streptomycin consists of three components, which are linked together by glycoside bonds, and it belongs to the group of the aminoglycoside antibiotics. Streptomycin is naturally produced by the actinobacterium Streptomyces griseus, and its activity is directed against gram-negative bacteria and the tubercle bacillus. Therapeutically it is used in the case of streptococcal and enterococcal enteritis. Because of its side effects (damage of equilibrium and auditory nerve, as well as the kidney) it is rarely used in the human treatment, but has an application in the veterinary area. After the treatment of mastitis in breeding animals, elevated streptomycin values were also measured in liver, kidney, muscle and milk. The maximum permissible values are in these cases: 500 μg/kg, 1000 μg/kg, 500 μg/kg and 200 μg/kg. Another application of the antibiotic streptomycin under the brand name of Plantomycin is the treatment of the illness of fruit trees called fire blight. In order to reduce the transmission to humans, maximum permissible values were defined in the European Union. The German critical value for streptomycin in honey according to the RHmV regulation is at the moment 20 μg/kg.
Description: The Streptomycin quantitative test is based on the principle of the enzyme-linked immunosorbent assay. An antibody directed against mouse immunoglobulins is coated on the surface of a microtiter plate. Streptomycin containing samples or standards and an antibody directed against streptomycin are given into the wells of the microtiter plate. The streptomycin contained in samples or standards will bind to the antibody which reacts with the anti-mouse antibody coated onto the microtiter plate. After 30 minutes incubation at room temperature a streptomycin-peroxidase conjugate is added into the wells without a preceding washing step to saturate free antibody binding sites. After additional 15 minutes incubation at room temperature the wells are washed with diluted washing solution to remove unbound material. A substrate solution is added and incubated for 15 minutes, resulting in the development of a blue colour. The colour development is inhibited by the addition of a stop solution, and the colour turns yellow. The yellow colour is measured photometrically at 450 nm. The concentration of streptomycin is indirectly proportional to the colour intensity of the test sample.
- The kit contains reagents for 96 determinations;
- Microtiter plate consisting of 12 strips with 8 breakable wells;
- Streptomycin Standards: 0, 2, 5, 20, 50, 200 ng/mL;
- ELISA reader at 450 nm;
- Standard range: 2 - 200 ng/mL;
- Sensitivity analytical: 1 ng/mL.