title: Turbidimetric assay of penicillin in feeds: addition of magnesium sulfate to eliminate chlortetracycline interference.
abstract: The official AOAC method for extracting penicillin from feeds allows some chlortetracycline to be co-extracted if the latter is also present in the sample. This can cause a high bias in results obtained by using the turbidimetric assay in which the test organism is sensitive to both antibiotics. In this report, we show that magnesium ions can be used to circumvent the interference of chlortetracycline in the turbidimetric assay for penicillin.
mesh_terms: D000821:Animal Feed / Q000032:analysis*; D002751:Chlortetracycline / Q000032:analysis*; D004340:Drug Contamination; D008278:Magnesium Sulfate; D009391:Nephelometry and Turbidimetry; D010406:Penicillins / Q000032:analysis*
chemical_list: D010406:Penicillins; D008278:Magnesium Sulfate; D002751:Chlortetracycline