title: Rapid quantitative chiral amphetamines liquid chromatography-tandem mass spectrometry: method in plasma and oral fluid with a cost-effective chiral derivatizing reagent.
abstract: Methamphetamine is a widely abused psychostimulant containing a chiral center. Consumption of over-the-counter and prescription medications may yield positive amphetamines results, but chiral separation of l- and d-methamphetamine and its metabolite amphetamine can help determine whether the source was licit or illicit. We present the first LC-MS/MS method with precolumn derivatization for methamphetamine and amphetamine chiral resolution in plasma and oral fluid collected with the Oral-Eze(®) and Quantisal™ devices. To 0.5mL plasma, 0.75mL Oral-Eze, or 1mL Quantisal specimen racemic d11-methamphetamine and amphetamine internal standards were added, followed by protein precipitation. Samples were centrifuged and supernatants loaded onto pre-conditioned Phenomenex(®) Strata™-XC Polymeric Strong Cation solid phase extraction columns. After washing, analytes were eluted with 5% ammonium hydroxide in methanol. The eluate was evaporated to dryness and reconstituted in water. Derivatization was performed with 1-fluoro-2,4-dinitrophenyl-5-l-alanineamide (Marfey's reagent) and heating at 45°C for 1h. Derivatized enantiomer separations were performed under isocratic conditions (methanol:water, 60:40) with a Phenomenex(®) Kinetex(®) 2.6μm C18 column. Analytes were identified and quantified by two MRM transitions and their ratio on a 3200 QTrap (AB Sciex) mass spectrometer in ESI negative mode. In all three matrices, the method was linear for all enantiomers from 1 to 500μg/L, with imprecision and accuracy of ≤11.3% and 85.3-108%, respectively. Extraction efficiencies ranged from 67.4 to 117% and matrix effects from -17.0 to 468%, with variation always ≤19.1%. Authentic plasma and OF specimens were collected from an IRB-approved study that included controlled Vicks(®) VapoInhaler™ administration. The present method is sensitive, selective, economic and rapid (separations accomplished in <10min), and improves methamphetamine result interpretation.
authors: Chemistry and Drug Metabolism Section, IRP, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA; Program in Toxicology, University of Maryland Baltimore, Baltimore, MD, USA.
authors: Matthew N
authors: MN
authors: Newmeyer
authors: Chemistry and Drug Metabolism Section, IRP, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA.
authors: Marta
authors: M
authors: Concheiro
authors: Chemistry and Drug Metabolism Section, IRP, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA. Electronic address: mhuestis@intra.nida.nih.gov.
authors: Marilyn A
authors: MA
authors: Huestis
mesh_terms: D000328:Adult; D000409:Alanine / Q000031:analogs & derivatives* / Q000737:chemistry; D000697:Central Nervous System Stimulants / Q000097:blood / Q000737:chemistry / Q000302:isolation & purification*; D002851:Chromatography, High Pressure Liquid / Q000592:standards; D004136:Dinitrobenzenes / Q000737:chemistry*; D006801:Humans; D057230:Limit of Detection; D008297:Male; D008694:Methamphetamine / Q000097:blood / Q000737:chemistry / Q000302:isolation & purification*; D012015:Reference Standards; D012463:Saliva / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization / Q000592:standards; D013237:Stereoisomerism; D053719:Tandem Mass Spectrometry / Q000592:standards
chemical_list: D000697:Central Nervous System Stimulants; D004136:Dinitrobenzenes; D008694:Methamphetamine; C047134:Marfey's reagent; D000409:Alanine
keywords: Amphetamines; Chiral analysis; Marfey's reagent; Oral fluid; Plasma