title: Liquid chromatography-mass spectrometric analysis of buprenorphine and its N-dealkylated metabolite norbuprenorphine in rat brain tissue and plasma.
abstract: BACKGROUND
  A specific, accurate, and reproducible liquid chromatography-mass spectrometric (LC/MS) method was developed and validated that allows simultaneous measurement of the centrally acting analgesic buprenorphine and its major metabolite, norbuprenorphine, in rat brain and plasma samples.
  
  
  METHODS
  A 96-well plate solid phase extraction (SPE) procedure was developed for buprenorphine and norbuprenorphine using mixed-mode cation-exchange reversed-phase sorbent. An LC method using a C8 column with isocratic mobile phase (80:20 water/acetonitrile with 20 mM ammonium acetate and 0.1% acetic acid) was developed for reproducible and selective separation. A quadrupole mass spectrometer with atmospheric electrospray ionization source under positive ion mode was used for detection. d4-Buprenorphine and d3-norbuprenorphine were used as internal standards.
  
  
  RESULTS
  The calibration curves for buprenorphine and norbuprenorphine in plasma and brain tissue were linear within the range of 7 to 8333 ng/ml (plasma) and 5 to 5000 ng/g (brain). The lower limit of quantification for both buprenorphine and norbuprenorphine from brain tissue was 5 ng/g, and from plasma was 7 ng/ml. Assay accuracy and precision of back-calculated standards were within +/-15%.
  
  
  CONCLUSIONS
  This method will be useful for investigation of buprenorphine's mechanism of action and clinical profile.
authors.affiliation: Department of Chemistry, Temple University, Philadelphia, PA 19140, USA.
authors.forename: Hongfei
authors.initials: H
authors.lastname: Yue
authors.forename: Michael R
authors.initials: MR
authors.lastname: Borenstein
authors.forename: Susan A
authors.initials: SA
authors.lastname: Jansen
authors.forename: Robert B
authors.initials: RB
authors.lastname: Raffa
mesh_terms: D000701:Analgesics, Opioid / Q000032:analysis* / Q000097:blood; D000818:Animals; D001923:Brain Chemistry; D002047:Buprenorphine / Q000031:analogs & derivatives* / Q000032:analysis* / Q000097:blood; D002853:Chromatography, Liquid / Q000379:methods*; D066298:In Vitro Techniques; D008297:Male; D051381:Rats; D012015:Reference Standards; D015203:Reproducibility of Results; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*
chemical_list: D000701:Analgesics, Opioid; D002047:Buprenorphine; C043585:norbuprenorphine