PH28-29: Chemical Residues Flashcards
Define Tolerable/Acceptable Dialy Intake. How do you calculated it?
An estimate of the amount of a food additive, expressed in milligrams on a body weight basis, that can be ingested daily over a life time without appreciable health risk.
Calculation of the ADI depends on the toxicology of the compound and its NOEL: (NOEL x 70kg) / 100
What is the maximum residue limit?
The maximum concentration of residue (expressed in mg/kg or μg/kg on a fresh weight basis) which may be accepted by the European Community to be legally permitted or recognized as acceptable in or on a food,
What are the withdrawal periods for meat from poultry, mammals, fish, milk, and eggs?
Meat from poultry and mammals: 28 days
Meat from fish: 500 degree days
Milk and eggs: 7 days
Define analyte and its relationship to the detection limit.
Analyte: a substance in a test sample, the presence of which has to be detected and/or quantified
Detection limit: the smallest analyte concentration for which a method has been validated with specified accuracy and precision
What are the difficulties in the analysis of residues?
Very low concentrations
Complex biological matrices
Multiplicity of substances derived from the parent compound
Methodology and pre-treatment of samples
Which animals are selected for testing?
Random: not from same producer, not from same animal, not same day, ensure in one year the OV tests as many different farm and animals as possible for different residues.
Suspect animals
How should samples be transferred to the lab?
Sample stored in a cold-box (e.g. dry ice) or a freezer and protected from light:
- Sulphadimidine residues decreases during storage
- Furazolidone is rapidly degraded post mortem
- Penicillin is sensitive to thermal degradation
- Chloramphenicol is rapidly degraded in liver
How are samples analysed?
Screening and confirmation
