Introduction
- Rapid analysis of 7 classes of antibiotics from meat products in less than 8 minutes results in shorter cycle times and improved productivity
- Ultra-high efficiency Kinetex core-shell columns provide narrower peaks and increased sensitivity

In modern mass production operations, many animal feeds, which are used in beef, pork, chicken and turkey production, contain antibiotics as prophylactics.1 The beta-lactam, macrolide, sulfonamide, tetracycline, and other antibiotics are an indispensable part of food animal production and help to maintain the optimal health of the animals. However, the residues of antibiotics remaining in animal-derived human foods may pose potential human health hazards toxicologically, microbiologically or immunopathologically.1, 2, 3, 4 Many countries have implemented a series of regulations governing the use, dosage, and withdrawal times for many of these antibiotic compound classes in animal production.
Experimental
Sample Preparation
1 gram of homogenized beef kidney, kidney juice, or serum was extracted using 10 mL of a 2:8 (v/v) mixture of water and acetonitrile and vortexed for 5 minutes. The sample was then centrifuged for 5 minutes and the supernatant decanted into a 50 mL tube containing 500 mg Strata® C18E SPE sorbent. The sample was again briefly vortexed, shaken for 30 seconds and centrifuged for 1 minute. A 5 mL aliquot of the resulting supernatant was transferred to a graduated tube and the contents evaporated down to less than 1 mL. The sample was then brought up to 1 mL total volume with water, and filtered (0.45 μm PVDF) prior to LC/MS/MS analysis.5 Chromatographic Conditions
The chromatographic system consisted of an Agilent 1100 series binary pump equipped with on-line solvent degasser, autosampler, and column temperature module (Palo Alto, California); interfaced with an Applied Biosystems 4000 QTRAP® LC/MS/MS system with Turbo VTM ion source. Positive polarity and negative polarity were monitored separately. The system was controlled using Analyst® software version 1.4.1.While there are several methods to determine antibiotic residues including bioassays, immunoassay, thin layer chromatography, and so on, LC/MS/MS is much more compelling due to its higher specificity and sensitivity, which leads to better quantitation and identification.1, 2 The method described here is for screening of seven classes of antibiotics: beta-lactam, tetracycline, sulfonamide, macrolide, amphenicol, fluoroquinolone, and flunixin. HPLC method development issues are explored and a newly introduced high efficiency core-shell particle is used as HPLC media to optimize retention and provide higher sensitivity of analysis.