title: High-performance liquid chromatographic determination of propofol in human plasma: comparison of different heteroscedastic calibration curve models.
abstract: OBJECTIVE
  The aim of this study was to select the best calibration model for determination of propofol plasma concentration by high-performance liquid chromatography method.
  
  
  METHODS
  Determination of propofol in plasma after deproteinization with acetonitrile containing thymol (as internal standard) was carried out on a C18 column with a mixture of acetonitrile and trifluoroacetic acid 0.1% (60:40) as mobile phase which delivered at the flow rate of 1.2 mL/minute . Fluorescence detection was done at the excitation and emission wavelengths of 276 and 310 nm, respectively. After fitting different equations to the calibration data using weighted regression, the adequacy of models were assessed by lack-of-fit test, significance of all model parameters, adjusted coefficient of determination (R(2) adjusted) and by measuring the predictive performance with median relative prediction error and median absolute relative prediction error of the validation data set.
  
  
  RESULTS
  The best model was a linear equation without intercept with median relative prediction error and median absolute relative prediction error of 4.0 and 9.4%, respectively in the range of 10-5000 ng/mL. The method showed good accuracy and precision.
  
  
  CONCLUSIONS
  The presented statistical framework could be used to choose the best model for heteroscedastic calibration data for analytes like propofol with wide range of expected concentration.
authors.affiliation: Department of Pharmaceutics, School of Pharmacy, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.
authors.forename: Pooria
authors.initials: P
authors.lastname: Taghavi Moghaddam
authors.affiliation: Anesthesia Department, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.
authors.forename: Mohammad Reza
authors.initials: MR
authors.lastname: Pipelzadeh
authors.affiliation: Anesthesia Department, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.
authors.forename: Sholeh
authors.initials: S
authors.lastname: Nesioonpour
authors.affiliation: Department of Otolaryngology, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.
authors.forename: Nader
authors.initials: N
authors.lastname: Saki
authors.affiliation: Department of Pharmaceutics, School of Pharmacy, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran. ; Nanotechnology Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran. ; Department of Pharmaceutics, School of Pharmacy, Zanjan University of Medical Sciences, Zanjan, Iran. (Current affiliation).
authors.forename: Saeed
authors.initials: S
authors.lastname: Rezaee
keywords: Calibration; Heteroscedasticty; High-performance liquid chromatography; Propofol; Weighted least squares regression