Date of Award

Fall 12-2021

Document Type


Degree Name

Master of Science (MS)


Forensic Science



First Advisor or Mentor

Marta Concheiro-Guisan

Second Reader

Teeshavi Acosta

Third Advisor

Sabra Botch-Jones


In forensic toxicological cases, sample stability and storage are pivotal for obtaining adequate analytical results. Currently, limited information is available about the impact of different preservatives and anticoagulants present in the blood tubes used in the collection of blood samples containing cannabinoids. This study investigated the impact of sodium fluoride (gray top) and sodium citrate (blue top) blood collection tubes on the concentrations of tetrahydrocannabinol (THC), cannabidiol (CBD), cannabinol (CBN) and 5 THC metabolites (THC-OH, THC-COOH, THC-diOH, THC-glucuronide, THCCOOH-glucuronide) in whole blood samples, stored at room temperature, 4ºC and -20ºC for up to 3.5 months. The samples were extracted using QuEChERS extraction technique. LC-MSMS quantification was performed in positive electrospray ionization mode, and two transitions were monitored using multiple reaction monitoring mode. In this method, the limits of quantification ranged from 0.5 – 5 ng/mL with a linearity range up to 100 ng/mL. Bias ranged from -4.9 to 25.2%, and all compounds also showed an acceptable imprecision, except THC-glucuronide and THC-diOH. Both extraction and process efficiency ranged from about 2.4% to 41.4%, and most of the analytes showed ion suppression at low concentrations (up to -61.4%) and no matrix effect at high. With respect to the stability studies, THC, THC-COOH, CBD and CBN were mostly stable, although stability issues occurred at low concentrations stored at -20°C after 3.5 months of storage. THCCOOH-glucuronide, THC-glucuronide and THC-OH showed some stability issues at room temperature, and THC-diOH was the most unstable analyte. Overall, better stability was achieved using sodium citrate collection tubes.


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