title: [Determination of free selenomethionine in cow milk by UPLC-MS/MS].
abstract: OBJECTIVE
  To establish an ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for the quantification of free selenomethionine (SeMet), and be applied to the quantification of free SeMet in cow milk.
  
  
  METHODS
  The analyte was separated on a BEH C18 column (2.1 mm x 100 mm, 1.7 μm) at 40 degrees C with a mobile phase of water: acetonitrile: formic acid (95: 5: 0.1, V/V) , a flow rate of 0.3 mL/min, and an analysis time of 2. 5 min. At positive electrospray ionization mode, multiple reaction monitoring of the precursor-product ion transitions of m/z 198.0 --> 181.1 was used for the quantification.
  
  
  RESULTS
  The linear calibration curve was obtained in a concentration range of 0.5 - 100 ng/mL with a lower limit of quantification of 0.5 ng/mL. The value of intra- and inter-day accuracy for SeMet fell in the range of 97.6%-100.6% and 97.7%-99.2%, and value of intra- and inter-day precision 0.53%-4.49% and 1.03%-4.54%.
  
  
  CONCLUSIONS
  The method is specific, sensitive, rapid, and accurate, suitable for the quantification of free SeMet in cow milk.
authors.forename: Mengjie
authors.initials: M
authors.lastname: He
authors.forename: Shuangqing
authors.initials: S
authors.lastname: Zhang
authors.forename: Minhui
authors.initials: M
authors.lastname: Liang
authors.forename: Yajuan
authors.initials: Y
authors.lastname: Cui
authors.forename: Mei
authors.initials: M
authors.lastname: He
authors.forename: Zhenwu
authors.initials: Z
authors.lastname: Huang
mesh_terms: D000818:Animals; D002417:Cattle; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D005260:Female; D005561:Formates; D008892:Milk / Q000737:chemistry*; D015203:Reproducibility of Results; D012645:Selenomethionine / Q000032:analysis*; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D005561:Formates; C030544:formic acid; D012645:Selenomethionine