Quantitative determination of amoxicillin in animal feed using liquid chromatography with tandem mass spectrometric detection

• Published in: Analytica chimica acta 2007-03, Vol.586 (1-2), p.319-325
• Main Authors: De Baere, S., De Backer, Patrick
• Format: Article
• Language: English
• Subjects: Amoxicillin; Amoxicillin - analysis; Ampicillin - analysis; Analytical chemistry; Animal feed; Animal Feed - analysis; Calibration; Chemistry; Chemistry Techniques, Analytical - methods; Chromatographic methods and physical methods associated with chromatography; Chromatography - methods; Chromatography, Liquid - methods; Drug Residues - analysis; Exact sciences and technology; Food Analysis - methods; General, instrumentation; Liquid chromatography-tandem mass spectrometry (LC-MS/MS); Mass Spectrometry - methods; Models, Chemical; Other chromatographic methods; Quality requirements; Reproducibility of Results; Sensitivity and Specificity; Spectrometric and optical methods
• ISSN: 0003-2670; 1873-4324
• DOI: 10.1016/j.aca.2006.10.036

A liquid chromatographic tandem mass spectrometric (LC-MS/MS) method for the determination of amoxicillin (AMO) in animal feed was developed and validated. The method was used to examine the quality requirements for products intended for incorporation into animal feedingstuffs (medicated premixes), as documented in the EMEA/CVMP/080/95-Final guideline. After addition of the internal standard (ampicillin), the medicated feed samples were extracted using a 0.01M potassium dihydrogenphosphate buffer solution (pH 4.5), followed by a centrifugation and filtration step. An appropriately diluted aliquot of the extract was analysed on a PLRP-S polymeric column (150mm×2.1mm i.d., 100Å) using a mixture of 0.1% formic acid in water and acetonitrile as the mobile phase. Gradient elution was performed at a flow-rate of 0.2mLmin−1. The mass spectrometer was used in the positive electrospray ionization MS/MS mode. The LC-MS/MS method was validated for linearity, trueness, precision, limit of quantification, limit of detection and specificity. The results fell within the ranges specified. The method was used for the homogeneity and stability testing of AMO in a commercial medicated feed. Some extracts were also injected onto a LC-UV and LC-fluorescence instrument (after pre-column derivatization with a formaldehyde reagent). These experiments showed that the LC-MS/MS method was superior with regard to speed of analysis, selectivity and sensitivity.