title: Rapid determination of hexapeptides by hydrophilic interaction LC-MS/MS for in vitro skin-penetration studies.
abstract: BACKGROUND
  A sensitive analytical method is needed for assessing penetration of topically applied peptides for in vitro skin-penetration studies.
  
  
  RESULTS
  A rapid hydrophilic interaction LC (HILIC)-MS/MS method for analyzing the polar peptides Ac-EEMQRR-amide and H2N-EEMQRR-amide in various skin layers and matrices has been developed and evaluated. The matrices included emulsion, receptor fluids, cotton-tipped applicators, stratum corneum tape strips, epidermis and dermis of the skin. Stable isotopically labeled analogues were used as internal standards to correct for recovery and matrix effects. A HILIC-SPE procedure was optimized to minimize significant ion suppression in the more complex matrices.
  
  
  CONCLUSIONS
  This HILIC-MS/MS method is applicable to the determination of Ac-EEMQRR-amide and H2N-EEMQRR-amide in complex skin samples and other matrices generated during in vitro skin-penetration studies.
authors.affiliation: US FDA, Center for Food Safety & Applied Nutrition, Office of Regulatory Science, College Park, MD 20740, USA.
authors.forename: Wanlong
authors.initials: W
authors.lastname: Zhou
authors.forename: Perry G
authors.initials: PG
authors.lastname: Wang
authors.forename: Oluwatosin A
authors.initials: OA
authors.lastname: Ogunsola
authors.forename: Margaret E K
authors.initials: ME
authors.lastname: Kraeling
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002853:Chromatography, Liquid / Q000191:economics / Q000379:methods*; D006168:Guinea Pigs; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D057230:Limit of Detection; D009842:Oligopeptides / Q000032:analysis / Q000493:pharmacokinetics*; D012867:Skin / Q000378:metabolism*; D012869:Skin Absorption; D053719:Tandem Mass Spectrometry / Q000191:economics / Q000379:methods*; D013997:Time Factors
chemical_list: D009842:Oligopeptides