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 0.5 mL plasma, 0.75 mL Oral-Eze, or 1 mL 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 1 h. Derivatized enantiomer separations were performed under isocratic conditions (methanol:water, 60:40) with a Phenomenex® Kinetex® 2.6 μm 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 1-500 μg/L, with imprecision and accuracy of ≤11.3% and 85.3-108%, respectively. Extraction efficiencies ranged from 67.4-117% and matrix effects from -17.0-468%, 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 <10 min), and improves methamphetamine result interpretation.

Determination of methamphetamine enantiomer composition in human hair by non-chiral liquid chromatography–tandem mass spectrometry method

“…The Marfey's derivitization and the LC-MS/MS parameters were similar to previously published methods [25][26][27]. In the extracts containing the cocktail of potentially interfering substances (including amphetamine, Fig.…”

“…It reacts quickly and efficiently with primary amines generating fairly stable derivatives [24]. Marfey's reagent has also been used for successful determination of enantiomeric composition of amphetamine-like compounds in biological samples [25], including urine [26], plasma, and oral fluid [27]. These applications have proven that Marfey's reagent derivatization eliminates the requirement of chiral chromatographic separation and/or specialized detection method.…”

Determination of amphetamines in biological samples using electro enhanced solid-phase microextraction-gas chromatography

“…Prior to chromatographic analysis, a sample preparation step is required to enrich and separate the amphetamines from biological fluids.. For this purpose, solid-phase extraction [5][6][7][8] and liquid-liquid extraction [9][10][11] are often used. .…”

Accelerated quantification of amphetamine enantiomers in human urine using chiral liquid chromatography and on-line column-switching coupled with tandem mass spectrometry

“…The most extensively used technique has been gas chromatography (GC) coupled with mass spectrometry (MS), comprising off-line derivatization with a chiral reagent and separation of the resulting diastereomeric derivatives on an achiral column, as recently reviewed [7]. Enantioseparation of AM after derivatization to diastereomers has also been achieved on conventional liquid chromatography (LC) stationary phases [8,9]. A possible drawback of this approach is that such derivatizing reagents might be less than 100% enantiomerically pure and that additional sample pretreatment steps are needed.…”