title: Headspace gas chromatographic method for the measurement of difluoroethane in blood.
abstract: OBJECTIVE
  To develop a gas chromatographic assay for the analysis of difluoroethane, a volatile substance, in blood and to determine assay characteristics including linearity, limit of quantitation, precision, and specificity.
  
  
  METHODS
  Referral toxicology laboratory
  
  
  RESULTS
  Difluoroethane, a colorless, odorless, highly flammable gas used as a refrigerant blend component and aerosol propellant, may be abused via inhalation. A headspace gas chromatographic procedure for the identification and quantitation of difluoroethane in blood is presented. A methanolic stock standard prepared from pure gaseous difluoroethane was used to prepare whole blood calibrators. Quantitation of difluoroethane was performed using a six-point calibration curve and an internal standard of 1-propanol. The assay is linear from 0 to 115 mg/L including a low calibrator at 4 mg/L, the limit of quantitation. Within-run coefficients of variation at mean concentrations of 13.8 mg/L and 38.5 mg/L were 5.8% and 6.8% respectively. Between-run coefficients of variation at mean concentrations of 15.9 mg/L and 45.7 mg/L were 13.4% and 9.8% respectively. Several volatile substances were tested as potential interfering compounds with propane having a retention time identical to that of difluoroethane.
  
  
  CONCLUSIONS
  This method requires minimal sample preparation, is rapid and reproducible, can be modified for the quantitation of other volatiles, and could be automated using an automatic sampler/injector system.
authors.affiliation: Department of Clinical Laboratory Sciences, LSU Health Sciences Center, 1900 Gravier, New Orleans, LA 70112, USA. lbrous@lsuhsc.edu
authors.forename: L A
authors.initials: LA
authors.lastname: Broussard
authors.forename: A
authors.initials: A
authors.lastname: Broussard
authors.forename: T
authors.initials: T
authors.lastname: Pittman
authors.forename: D
authors.initials: D
authors.lastname: Lafferty
authors.forename: L
authors.initials: L
authors.lastname: Presley
mesh_terms: D000280:Administration, Inhalation; D000293:Adolescent; D002138:Calibration; D002849:Chromatography, Gas / Q000379:methods*; D006801:Humans; D006845:Hydrocarbons, Fluorinated / Q000009:adverse effects / Q000097:blood*; D012680:Sensitivity and Specificity; D019966:Substance-Related Disorders / Q000175:diagnosis; D014835:Volatilization
chemical_list: D006845:Hydrocarbons, Fluorinated; C059268:1,1-difluoroethane