title: A rapid method based on hot water extraction and liquid chromatography-tandem mass spectrometry for analyzing tetracycline antibiotic residues in cheese.
abstract: A rapid, specific, and sensitive procedure for determining residues of 4 widely used tetracycline antibiotics and 3 of their 4-epimers in cheese is presented. The method is based on the matrix solid-phase dispersion (MSPD) technique followed by liquid chromatography/tandem mass spectrometry (LC/MS/MS). After dispersing samples of mozzarella, asiago, parmigiano, gruyere, emmenthal, and camembert on sand, target compounds were eluted from the MSPD column by passing through it 6 mL water heated at 70 degrees C. After acidification and filtration, 200 microL of the aqueous extract was directly injected into the LC column. For analyte identification and quantification, MS data acquisition was performed in the multireaction monitoring mode, selecting 2 precursor ion-to-product ion transitions for each target compound. Hot water appeared to be an efficient extractant, because absolute recoveries were no lower than 78%. Using demeclocycline as a surrogate analyte, recoveries of analyte added to the 6 types of cheeses at the 30 ng/g level were 96-117%, with relative standard deviation (RSD) not higher than 9%. Statistical analysis of the mean recovery data showed that the extraction efficiency was not dependent on the type of cheese analyzed. This result indicates that this method could be applied to other cheese types not considered here. At the lowest concentration considered, i.e., 10 ng/g, the accuracy of the method ranged between 90 and 107%, with RSDs not larger than 12%. Based on a signal-to-noise ratio of 10, limits of quantitation were estimated to be 1-2 ng/g.
authors.affiliation: Università "La Sapienza," Dipartimento di Chimica, Piazza Aldo Moro 5, 00185 Roma, Italy.
authors.forename: Sara
authors.initials: S
authors.lastname: Bogialli
authors.forename: Cristina
authors.initials: C
authors.lastname: Coradazzi
authors.forename: Antonio
authors.initials: A
authors.lastname: Di Corcia
authors.forename: Aldo
authors.initials: A
authors.lastname: Lagana
authors.forename: Manuel
authors.initials: M
authors.lastname: Sergi
mesh_terms: D000900:Anti-Bacterial Agents / Q000032:analysis; D002611:Cheese / Q000032:analysis*; D002751:Chlortetracycline / Q000737:chemistry; D002853:Chromatography, Liquid / Q000379:methods*; D003707:Demeclocycline / Q000032:analysis; D004305:Dose-Response Relationship, Drug; D004350:Drug Residues / Q000032:analysis*; D005504:Food Analysis / Q000379:methods*; D005506:Food Contamination; D013058:Mass Spectrometry / Q000379:methods*; D008956:Models, Chemical; D015203:Reproducibility of Results; D013696:Temperature; D013754:Tetracyclines / Q000032:analysis*; D014867:Water / Q000737:chemistry
chemical_list: D000900:Anti-Bacterial Agents; D013754:Tetracyclines; D014867:Water; D003707:Demeclocycline; D002751:Chlortetracycline