Sensitive determination of THC and main metabolites in human plasma by means of microextraction in packed sorbent and gas chromatography-tandem mass spectrometry.
Cannabis is one of the most available and consumed illicit drug in the world and its identification and quantification in biological specimens can be a challenge given its low concentrations in body fluids. The present work describes a fast and fully validated procedure for the simultaneous detection and quantification of ▵9-tetrahydrocannabinol (▵9_THC) and its two main metabolites 11-hydroxy ▵9_tetrahydrocannabinol (11-OH-THC) and 11-nor-9-carboxy-▵9- tetrahydrocannbinol (THC-COOH) in plasma samples using microextraction by packed sorbent (MEPS) and gas chromatography-tandem mass spectrometry (GC-MS/MS). A small plasma volume (0.25mL) pre-diluted (1:20), was extracted with MEPS M1 sorbent as follows: conditioning (4 cycles of 250μL methanol and 4 cycles of 250μL 0.1% formic acid in water); sample load (26 cycles of 250μL); wash (100μL of 3% acetic acid in water followed by 100μL 5% methanol in water); and elution (6 cycles of 100μL of 10% ammonium hydroxide in methanol). The procedure allowed the quantification of all analytes in the range of 0.1-30ng/mL. Recoveries ranged from 53 to 78% (THC), 57 to 66% (11-OH-THC) and 62 to 65% (THC-COOH), allowing the limits of detection and quantification to be set at 0.1ng/mL for all compounds. Intra-day precision and accuracy revealed coefficients of variation (CVs) lower than 10% at the studied concentrations, with a mean relative error within±9%, while inter-day precision and accuracy showed CVs lower than 15% for all analytes at the tested concentrations, with an inaccuracy within±8%.
Centro de Investigação em Ciências da Saúde, Faculdade de Ciências da Saúde da Universidade da Beira Interior (CICS-UBI), Covilhã, Portugal; Laboratório de Fármaco-Toxicologia-UBIMedical, Universidade da Beira Interior, Covilhã, Portugal.
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Rosado
Centro de Investigação em Ciências da Saúde, Faculdade de Ciências da Saúde da Universidade da Beira Interior (CICS-UBI), Covilhã, Portugal.
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Fernandes
Serviço de Química e Toxicologia Forenses, Instituto de Medicina Legal e Ciências Forenses-Delegação do Sul, Rua Manuel Bento de Sousa, Lisboa, Portugal.
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Barroso
Centro de Investigação em Ciências da Saúde, Faculdade de Ciências da Saúde da Universidade da Beira Interior (CICS-UBI), Covilhã, Portugal; Laboratório de Fármaco-Toxicologia-UBIMedical, Universidade da Beira Interior, Covilhã, Portugal. Electronic address: egallardo@fcsaude.ubi.pt.
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Gallardo
D013759:Dronabinol / Q000097:blood* / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D004355:Drug Stability; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D006801:Humans; D057230:Limit of Detection; D016014:Linear Models; D015203:Reproducibility of Results; D052617:Solid Phase Microextraction / Q000379:methods*
D013759:Dronabinol
Cannabis; Gas chromatography–tandem mass spectrometry; Microextraction by packed sorbent; Plasma