title: High throughput screening of sub-ppb levels of basic drugs in equine plasma by liquid chromatography-tandem mass spectrometry.
abstract: This paper describes a high throughput LC-MS-MS method for the screening of 75 basic drugs in equine plasma at sub-ppb levels. The test scope covers diversified classes of drugs including some alpha- and beta-blockers, alpha- and beta-agonists, antihypotensives, antihypertensives, analgesics, antiarrhythmics, antidepressants, antidiabetics, antipsychotics, antiulcers, anxiolytics, bronchodilators, CNS stimulants, decongestants, sedatives, tranquilizers and vasodilators. A plasma sample was first deproteinated by addition of trichloroacetic acid. Basic drugs were then extracted by solid-phase extraction (SPE) using a Bond Elut Certify cartridge, and analysed by LC-MS-MS in positive electrospray ionization (+ESI) and multiple reaction monitoring (MRM) mode. Liquid chromatography was performed using a short C(8) column (3.3 cm L x 2.1mm ID with 3 microm particles) to provide fast analysis time. The overall instrument turnaround time was 8 min, inclusive of post-run and equilibration time. No interference from the matrices at the expected retention times of the targeted masses was observed. Over 60% of the drugs studied gave limits of detection (LoD) at or below 25 pg/mL, with some LoDs reaching down to 0.5 pg/mL. The inter-day precision for the relative retention times ranged from 0.01 to 0.54%, and that for the relative peak area ratios (relative to the internal standard) ranged from 4 to 37%. The results indicated that the method has acceptable precision to be used on a day-to-day basis for qualitative identification.
authors.affiliation: Racing Laboratory, The Hong Kong Jockey Club, Sha Tin Racecourse, Sha Tin, NT, Hong Kong, China. gary.nw.leung@hkjc.org.hk
authors.forename: Gary N W
authors.initials: GN
authors.lastname: Leung
authors.forename: David K K
authors.initials: DK
authors.lastname: Leung
authors.forename: Terence S M
authors.initials: TS
authors.lastname: Wan
authors.forename: Colton H F
authors.initials: CH
authors.lastname: Wong
mesh_terms: D000818:Animals; D002077:Butorphanol / Q000097:blood; D002853:Chromatography, Liquid / Q000379:methods*; D002976:Clenbuterol / Q000097:blood; D006736:Horses / Q000097:blood*; D008012:Lidocaine / Q000097:blood; D004364:Pharmaceutical Preparations / Q000097:blood* / Q000652:urine; D052616:Solid Phase Extraction / Q000379:methods; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D004364:Pharmaceutical Preparations; D008012:Lidocaine; D002077:Butorphanol; D002976:Clenbuterol