title: Fully automated analysis of beta-lactams in bovine milk by online solid phase extraction-liquid chromatography-electrospray-tandem mass spectrometry.
abstract: A fully automated method for the detection of beta-lactam antibiotics, including six penicillins (amoxicillin, ampicillin, cloxacillin, dicloxacillin, oxacillin, and penicillin G) and four cephalosporins (cefazolin, ceftiofur, cefoperazone, and cefalexin) in bovine milk samples has been developed. The outlined method is based on online solid-phase extraction-liquid chromatography/electrospray-tandem mass spectrometry (SPE-LC/ESI-MS-MS). Target compounds were concentrated from 500 microL of centrifuged milk samples using an online SPE procedure with C18 HD cartridges. Target analytes were eluted with a gradient mobile phase (water + 0.1% formic acid/methanol + 0.1% formic acid) at a flow rate of 0.7 mL/min. Chromatographic separation was achieved within 10 min using a C-12 reversed phase analytical column. For unequivocal identification and confirmation, two multiple reaction monitoring (MRM) transitions were acquired for each analyte in the positive electrospray ionization mode (ESI(+)). Method limits of detection (LODs) in milk were well below the maximum residue limits (MRLs) set by the European Union for all compounds. Limits of quantification in milk were between 0.09 ng/mL and 1.44 ng/mL. The developed method was validated according to EU's requirements, and accuracy results ranged from 80 to 116%. Finally, the method was applied to the analysis of twenty real samples previously screened by the inhibition of microbial growth test Eclipse 100. This new developed method offers high sensitivity and accuracy of results, minimum sample pre-treatment, and uses for the first time an automated online SPE offering a high throughput analysis. Because of all these characteristics, the proposed method is applicable and could be deemed necessary within the field of food control and safety.
authors.affiliation: Department of Environmental Chemistry, IDAEA-CSIC, c/Jordi Girona 18-26, 08034, Barcelona, Spain.
authors.forename: Lina
authors.initials: L
authors.lastname: Kantiani
authors.forename: Marinella
authors.initials: M
authors.lastname: Farré
authors.forename: Martin
authors.initials: M
authors.lastname: Sibum
authors.forename: Cristina
authors.initials: C
authors.lastname: Postigo
authors.forename: Miren
authors.initials: M
authors.lastname: López de Alda
authors.forename: Damiá
authors.initials: D
authors.lastname: Barceló
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000032:analysis*; D002417:Cattle; D002853:Chromatography, Liquid / Q000379:methods*; D004867:Equipment Design; D008892:Milk / Q000737:chemistry*; D012680:Sensitivity and Specificity; D052616:Solid Phase Extraction / Q000295:instrumentation / Q000379:methods*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods; D053719:Tandem Mass Spectrometry / Q000379:methods*; D047090:beta-Lactams / Q000032:analysis*
chemical_list: D000900:Anti-Bacterial Agents; D047090:beta-Lactams