Rwanda Standards Board

Testing of antibiotics residues in food

1.    Introduction

Antibiotics are substances either produced naturally by living organisms or produced synthetically in the laboratory, and they are able to kill or inhibit the growth of microorganisms. Antibiotics can be classified according to (a) their effects as either bactericidal or bacteriostatic and also according to (b) their range of efficacy as narrow or broad in spectrum. Bactericidal kill bacteria directly, whereas bacteriostatics prevent them from dividing (multiplication).


The use of antibiotics in animals shortly followed their use in humans for the purpose of disease prevention and treatment. Today, antimicrobial drugs, including antibiotics, are used to control, prevent, and treat infection and to enhance animal growth and feed efficiency. Currently, most of food producing animal receive medication. The antimicrobials usually used are the β – Lactams, Tetracyclines, Aminoglycosides, Lincosamides, Macrolides, Pleuromutilins and Sulfonamides.


2.     Antibiotics residues in Food


The foodstuffs of animal origin like meat, milk, honey and eggs may present antibiotic residues from their direct application to these animals during their medication. Antibiotic residues in foods produced by animals may be the cause of numerous health hazards in humans. These problems include toxic effects, transfer of antibiotic resistant bacteria to humans, immunopathological effects, carcinogenicity (e.g., sulphamethazine, oxytetracycline, and furazolidone), mutagenicity, nephropathy (e.g., gentamicin), hepatotoxicity, reproductive disorders, bone marrow toxicity (e.g., chloramphenicol), and allergy (e.g., penicillin)


Therefore, animal foodstuff products processors should test of these antibiotic residues in their products for the welfare of the consumers of their products. This testing is for comparing their results with recommended maximum residue limits established by WHO or CODEX standards. For example, the Maximum Residue Limits (MRL) for amoxicillin updated up to 35th Session of the Codex Alimentarius Commission (2012) for milk of cattle is 4µg/kg and for muscle, liver and kidney for cattle, the MRLs are 50µg/kg for each tissue. There are limits for each type of veterinary drug residues for all types of foodstuffs.

3.    Laboratory Testing of Antibiotics residue


There are so different techniques that can be used for the analysis of antibiotic residues in foodstuffs. The most common used are the following:
    Liquid Chromatography with Triple Quadrupole Mass Spectrophotometer (LCQQQ)
    HPLC (High Performance Liquid Chromatography)
    GC (Gas Chromatography)
    Paper Chromatography
    ELISA(Enzyme-Linked ImmunoSorbent Assay)


For the purpose of laboratory testing of antibiotics residues, RSB has acquired the Liquid Chromatography with Triple Quadrupole Mass Spectrophotometer (LCQQQ)

Photo of Agilent technologies 6430 Triple Quad LC/MS used in RBS (Organic Chemistry Lab)


Rwanda Standards Board Testing Laboratory has approved test methods for the following antibiotics residues in food samples:
    Chloramphenicol
    Amoxicillin
    Ampicillin
    Penecellium G


The verification process for other antibiotics residues has also started and the testing scope will keep increasing depending on customer demand.


4.    Prevention of Antibiotics residues


Animal food stuff products processors (industries) need more training on quality control (QC) of food stuff from animals: the way to feed, to treat, and how to perform the specific process up to product.


Moreover, to prevent the antibiotic residues in our products, we need to strengthen our legislation about these chemicals by developing standards with the maximum residue limits for every antibiotic even for all veterinary drugs, directives for the use of these chemicals and the permanent monitoring of their application and use for the food – producing firms.


In few words, all animal food staff processors have to take and perform preventive actions, in order to minimize the antibiotic residues in final products intended to consumption for consumer protection.


RSB friendly team is happy to be contacted for any information or question regarding certification. Contact them through:
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