title: [High performance liquid chromatography coupled with electrospray tandem mass spectrometry for the analysis of dicyandiamide and melamine residues in milk and milk products].
abstract: OBJECTIVE
  To establish a sensitive method for the analysis of dicyanodiamide and melamine residue in milk and milk products by, hydrophilic interaction liquid chromatography coupled with electrospray tandem mass spectrometry.
  
  
  METHODS
  Samples were extracted with 2.5% (V/V) formic acid solution. Acetonitrile was used to precipitate proteins. The separation was carried on Acquity UPLC BEH Amide column (100 mm x 2.1 mm x 1.7 mm) by gradient elution with acetonitrile - water as mobile phase. Identification was achieved by electrospray ionization (ESI) in positive mode using multiple reaction monitoring, and quantified with external standards.
  
  
  RESULTS
  The dicyanodiamide and melamine were linear in the range of 5.0 - 1000.0 μg/L with correlation coefficient of 0.9995 for dicyanodiamide and 0.9997 for melamine. The detection limit of the method were 10.0 μg/kg for dicyanodiamide and melamine. The spiked at three levels ranged 86.0% - 100.0% (0.050 mg/kg), 90.0% - 104.0% (1.0 mg/kg) and 90.0% - 100.1% (10.0 mg/kg). And the relative standard derivations were lower than 1.06% -7.77%. The within-day precisions were 2.35% (dicyanodiamide) and 3.44% (melamine), and the inter-day precision 3.87% (dicyanodiamide) and 5.39% (melamine).
  
  
  CONCLUSIONS
  The method was sensitive, accurate and precise. It can be used in monitoring quality of milk production and daily analysis of milk and milk products.
authors.affiliation: Shenzhen Center for Disease Control and Prevention, Shenzhen 518055, China. 532294960@qq.com
authors.forename: Honghe
authors.initials: H
authors.lastname: Liu
authors.forename: Shicheng
authors.initials: S
authors.lastname: Liao
authors.forename: Li
authors.initials: L
authors.lastname: Kang
authors.forename: Lisha
authors.initials: L
authors.lastname: Mao
authors.forename: Ruiyuan
authors.initials: R
authors.lastname: Li
mesh_terms: D000818:Animals; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D003611:Dairy Products / Q000032:analysis*; D005504:Food Analysis / Q000379:methods; D005506:Food Contamination / Q000032:analysis; D006146:Guanidines / Q000032:analysis / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D057230:Limit of Detection; D008892:Milk / Q000737:chemistry* / Q000592:standards; D012015:Reference Standards; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D053719:Tandem Mass Spectrometry / Q000379:methods*; D014227:Triazines / Q000032:analysis / Q000737:chemistry*
chemical_list: D006146:Guanidines; D014227:Triazines; C004711:dicyandiamido; C011907:melamine