title: Development and validation of an ultraviolet-visible spectrophotometric method for determination of phenylethyl resorcinol in new topical nanoemulsions.
abstract: OBJECTIVE
  To develop a rapid, simple and efficient ultraviolet-visible (UV-vis) spectrophotometric method for the quantification of phenylethyl resorcinol (PR), a potent skin-lightening agent, incorporated into new topical nanoemulsions, and to validate this method according to International Commission for Harmonization (ICH) guidelines.
  
  
  METHODS
  UV-vis spectrophotometric method for quantification of PR in new topical nanoemulsions was developed and validated in terms of specificity, linearity, sensitivity, precision and accuracy. The method was applied to determine PR content (extraction recoveries) in the nanoemulsions and entrapment efficiencies.
  
  
  RESULTS
  The calibration curve for PR was linear in the range of 10-60 μg mL-1, with a determination coefficient (r2) which is higher than 0.999. The limit of detection (LOD) and limit of quantitation (LOQ) were 1.55 and 4.69 μg mL-1, respectively. The method was shown to be specific, precise [intraday, interday and reproducibility levels relative standard deviation < 3%] and accurate (between 91.90 ± 1.28% and 104.73 ± 0.60%). The extraction recoveries of PR in nanoemulsions were 97.07%, 96.64% and 103.54% at concentrations of 3, 6 and 9 mg mL-1, respectively. The entrapment efficiencies were nearly 100%, which agrees with the oil core location of PR in nanoemulsions.
  
  
  CONCLUSIONS
  This developed method was confirmed to be rapid, simple, cost-effective, specific, precise, accurate and suitable for determination of PR content in nanoemulsions and entrapment efficiencies.
authors.affiliation: College of Marine Life Science, Ocean University of China, Qingdao, 266003, China.
authors.forename: L
authors.initials: L
authors.lastname: Hong
authors.affiliation: College of Marine Life Science, Ocean University of China, Qingdao, 266003, China.
authors.forename: D
authors.initials: D
authors.lastname: Han
authors.affiliation: College of Marine Life Science, Ocean University of China, Qingdao, 266003, China.
authors.forename: M-X
authors.initials: MX
authors.lastname: Li
authors.affiliation: Department of Life Science, Luoyang Normal University, Luoyang, 471934, China.
authors.forename: P
authors.initials: P
authors.lastname: Zhang
authors.affiliation: College of Marine Life Science, Ocean University of China, Qingdao, 266003, China.
authors.forename: C-G
authors.initials: CG
authors.lastname: Liu
mesh_terms: D000287:Administration, Topical; D001559:Benzhydryl Compounds / Q000008:administration & dosage / Q000032:analysis*; D002138:Calibration; D004655:Emulsions / Q000737:chemistry*; D057230:Limit of Detection; D036103:Nanotechnology; D015203:Reproducibility of Results; D012118:Resorcinols / Q000008:administration & dosage / Q000032:analysis*; D062327:Skin Lightening Preparations / Q000008:administration & dosage / Q000032:analysis*; D013056:Spectrophotometry, Ultraviolet / Q000379:methods*
chemical_list: D001559:Benzhydryl Compounds; D004655:Emulsions; D012118:Resorcinols; D062327:Skin Lightening Preparations; C512391:4-(1-phenylethyl)-1,3-benzenediol
keywords: chemical analysis; emulsions; phenylethyl resorcinol; spectroscopy; validation