Related Experiment Video
Updated: Jan 27, 2026
08:41
Identification of Fatty Acids in Bacillus cereus
Published on: December 5, 2016
10.1K
Detectability and Precision of the AOAC Bacillus stearothermophilus Disc Assay Demonstrated in the 1981 FDA Split
J T Peeler1, J E Leslie1, J E Barnett1
1Division of Microbiology, Food and Drug Administration, 1090 Tusculum Avenue, Cincinnati, Ohio 45226.
Journal of Food Protection
|March 28, 2019
Summary
This study compared four methods for detecting beta-lactam residues in milk. Antibiotic 4 (A4) agar with incubation at 55°C or 64°C, and PM indicator (PMI) agar with 55°C or 64°C incubation, showed high detection rates for beta-lactam antibiotics.
Area of Science:
- Food safety analysis
- Microbiological testing
- Analytical chemistry
Background:
- Beta-lactam antibiotics are widely used in dairy production.
- Residues of beta-lactams in milk pose a risk to human health and can trigger allergic reactions.
- Accurate and reliable detection methods are crucial for regulatory compliance and consumer protection.
Purpose of the Study:
- To evaluate the performance of four official variations for detecting beta-lactam residues in milk.
- To compare the sensitivity and accuracy of different agar media and incubation temperatures.
- To determine the optimal conditions for reliable beta-lactam residue analysis.
Main Methods:
- Analysis of blind duplicate milk samples fortified with known beta-lactam concentrations.
- Utilized four testing variations: Antibiotic 4 (A4) agar at 55°C and 64°C, and PM indicator (PMI) agar at 55°C and 64°C.
- Quantified detection rates and measured average zone diameters for each variation.
Main Results:
- All four variations achieved high detection rates for 0.008 IU/ml beta-lactam concentration (98-100%).
- Detection rates for 0.005 IU/ml varied: A4 agar at 64°C (99%) and A4 agar at 55°C (92%) performed best.
- PMI agar showed lower detection rates, especially at 55°C (57%).
Conclusions:
- Antibiotic 4 (A4) agar demonstrates superior performance for detecting lower concentrations of beta-lactam residues in milk.
- Incubation temperature significantly impacts the sensitivity of the detection methods.
- Optimized methods using A4 agar are recommended for reliable beta-lactam residue screening in dairy products.
Related Concept Videos
01:26FDA Approved Drugs: Changes to Approved Drugs
252
Post-approval, manufacturers may modify an approved new or generic drug product. Such modifications can encompass alterations in the Active Pharmaceutical Ingredient (API), manufacturing process, formulation, batch size, manufacturing site, and container closure system (FDA Guidance for Industry, April 2004). Often, a drug product may undergo multiple changes.These modifications require careful evaluation to determine their potential impact on the drug product's identity, strength, quality,...
252
01:13¹H NMR: Complex Splitting
1.8K
A proton M that is coupled to a proton X results in doublet signals for M. However, NMR-active nuclei can be simultaneously coupled to more than one nonequivalent nucleus. When M is coupled to a second proton A, such as in styrene oxide, each peak in the doublet is split into another doublet.
Splitting diagrams or splitting tree diagrams are routinely used to depict such complex couplings. While drawing splitting diagrams, the splitting with the larger coupling constant is usually applied...
Splitting diagrams or splitting tree diagrams are routinely used to depict such complex couplings. While drawing splitting diagrams, the splitting with the larger coupling constant is usually applied...
1.8K
03:37Uncertainty in Measurement: Accuracy and Precision
100.7K
Scientists typically make repeated measurements of a quantity to ensure the quality of their findings and to evaluate both the precision and the accuracy of their results. Measurements are said to be precise if they yield very similar results when repeated in the same manner. A measurement is considered accurate if it yields a result that is very close to the true or the accepted value. Precise values agree with each other; accurate values agree with a true value.
100.7K
01:52Accuracy and Precision
15.0K
Scientists typically make repeated measurements of a quantity to ensure the quality of their findings and to evaluate both the precision and the accuracy of their results. Measurements are said to be precise if they yield very similar results when repeated in the same manner. A measurement is considered accurate if it yields a result that is very close to the true or the accepted value. Precise values agree with each other; accurate values agree with a true value. Highly accurate...
15.0K
01:13¹H NMR Signal Multiplicity: Splitting Patterns
6.5K
When protons A and X are coupled, their nuclear spin energy levels are slightly modified. This is because the energy required to excite proton A to a spin state parallel to proton X is slightly different from the energy required for it to become anti-parallel to spin X. Consequently, there are two possible excitation frequencies for A (A1 and A2), depending on the spin state of X, and vice versa. The mutual nature of coupling implies that the difference between frequencies A1 and A2, indicated...
6.5K
01:10Interpreting ¹H NMR Signal Splitting: The (n + 1) Rule
2.5K
In the AX proton spin system, proton A can sense the two spin states of a coupled proton X, resulting in a doublet NMR signal with two peaks of equal (1:1) intensity. When proton A is coupled to two equivalent protons (AX2 spin system), the spin states of each X can be aligned with or against the external field, creating three possible scenarios. This results in a 1:2:1 triplet signal, where the central peak corresponds to the chemical shift of A and is twice as large or intense as the...
2.5K