title: Opiorphin analysis in equine plasma and urine using hydrophilic interaction LC-MS.
abstract: BACKGROUND
  Due to opiorphin's analgesic and antidepressant functions, its illicit use is rumored in some racing jurisdictions. Opiorphin is very difficult to detect due to its hydrophilic nature and rapid degradation in plasma and urine samples. METHODOLOGY & RESULTS: We have developed a sensitive, reliable method for opiorphin detection and confirmation in equine samples, using EDTA to inhibit analyte degradation between the time of collection and analysis. Opiorphin was extracted by weak cation exchange followed by analysis using HILIC-MS/MS. The method was validated and the LOD was determined to be 50 pg/ml in equine plasma and urine.
  
  
  CONCLUSIONS
  The method has good selectivity and precision and is the first reported method for the detection of opiorphin in equine plasma and urine.
authors.affiliation: Industrial Laboratories, Drug Testing Services, Wheat Ridge, CO 80033, USA.
authors.forename: Caroline C
authors.initials: CC
authors.lastname: Wang
authors.forename: Petra
authors.initials: P
authors.lastname: Hartmann-Fischbach
authors.forename: Tim R
authors.initials: TR
authors.lastname: Krueger
authors.forename: Terry L
authors.initials: TL
authors.lastname: Wells
authors.forename: Aaron
authors.initials: A
authors.lastname: Simonson
authors.forename: Joanne C
authors.initials: JC
authors.lastname: Compton
mesh_terms: D000818:Animals; D002853:Chromatography, Liquid / Q000379:methods; D006736:Horses; D057927:Hydrophobic and Hydrophilic Interactions; D009842:Oligopeptides / Q000032:analysis / Q000097:blood* / Q000737:chemistry / Q000652:urine*; D012471:Salivary Proteins and Peptides / Q000032:analysis / Q000097:blood* / Q000737:chemistry / Q000652:urine*; D053719:Tandem Mass Spectrometry / Q000379:methods
chemical_list: D009842:Oligopeptides; D012471:Salivary Proteins and Peptides; C517879:glutaminyl-arginyl-phenylalanyl-seryl-arginine