title: [Determination of 7 penicilins and penicilloic acids in milk products by high performance liquid chromatography-tandem mass spectrometry].
abstract: OBJECTIVE
  A high performance liquid chromatography-tandem mass spectrometric method was established for determination of 7 penicilins (cloxacillin, nafcillin, oxacillin, penicillin V, amoxicillin, penicillin G, ampicillin) and their penicilloic acids (cloxacilloic acid, nafcilloic acid, oxacilloic acid, penicilloic acid V, amoxicilloic acid, penicilloic acid G and ampicilloic acid) in milk products. And the 7 penicilins and penicilloic acids in milk products were surveyed.
  
  
  METHODS
  The 7 penicilins and penicilloic acids in milk products were extracted by water in super-sonic instrument , precipitated proteins by acetonitrile and degreased fat by n-hexane with liquid-liquid extraction, then the purified solution was concentrated by nitrogen, dissolved with acetonitrile-water (10 + 90, V/V) and cleaned by 0.22 µm millipore filter. The filtrate was detected by high performance liquid chromatography-tandem mass spectrometry, identified by electrospray ionization (ESI) in positive mode using multiple reaction monitoring, and quantified with external standards.
  
  
  RESULTS
  The calibration curves of 7 penicilins and penicilloic acids showed good linearity in the range of 1.0-200 µg/kg with correlation coefficients were above 0.9992. The detection limits of the method were from 0.03 µg/kg to 0.15 µg/kg. The recoveries of three spiking levels ranged from 80.0% to 110.0%, and RSDs of 7.06% or less were obtained.
  
  
  CONCLUSIONS
  The method for determination of 7 penicilins and penicilloic acids in milk products by HPLC-MS/MS was of operation convenience, less interference from impurities and good accuracy, which could meet the requirements for the determination of 7 penicilins and penicilloic acids residues in milk products.
authors.forename: Huizhen
authors.initials: H
authors.lastname: Xiao
authors.forename: Honghe
authors.initials: H
authors.lastname: Liu
authors.forename: Jiangwei
authors.initials: J
authors.lastname: Yin
authors.forename: Likang
authors.initials: L
authors.lastname: Wu
authors.forename: Biru
authors.initials: B
authors.lastname: Lu
authors.forename: Jing
authors.initials: J
authors.lastname: Li
authors.forename: Zhen
authors.initials: Z
authors.lastname: Zhen
mesh_terms: D000818:Animals; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D003611:Dairy Products; D004350:Drug Residues / Q000032:analysis; D006586:Hexanes; D008892:Milk / Q000737:chemistry*; D010397:Penicillanic Acid / Q000031:analogs & derivatives* / Q000032:analysis; D010400:Penicillin G; D010406:Penicillins / Q000032:analysis*; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D006586:Hexanes; D010406:Penicillins; C008782:penicilloic acid; C026385:n-hexane; D010397:Penicillanic Acid; D010400:Penicillin G