Measurement uncertainty in quantifying delta-9-tetrahydrocannabinol (THC) in blood using SPE and LC/MS/MS

Joyce K. Klu (Lead / Corresponding author), Jane A. Officer, Alexandra Park, Roy Mudie, Niamh Nic Daeid

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)
198 Downloads (Pure)


A method for the quantitative analysis of delta-9-tetrahydrocannabinol (THC, the main active ingredient of cannabis) in whole blood using solid phase extraction and LC/MS/MS has been developed. A bottom-up approach with method validation data was used to evaluate and estimate the measurement uncertainty (MU) of the analytical method. The sources of uncertainty were identified using a cause and effect diagram. The contribution of each uncertainty component was estimated and were combined to derive the overall uncertainty of the analytical method. The combined uncertainty was estimated to be 0.131 μg/L (<7%). At a 99.7% confidence level, the expanded uncertainty was 0.393 μg/L for a THC concentration of 2 μg/L in a whole blood sample. The calculations not only enable the laboratory to quantify the uncertainty associated with a quantitative result, but can also be used to identify the sources of uncertainty and determine if the analytical method can be improved.
Original languageEnglish
Article number110744
Number of pages9
JournalForensic Science International
Early online date22 Feb 2021
Publication statusPublished - May 2021


  • Measurement uncertainty
  • Calibration curve
  • Method validation
  • Bottom-up approach

ASJC Scopus subject areas

  • Pathology and Forensic Medicine


Dive into the research topics of 'Measurement uncertainty in quantifying delta-9-tetrahydrocannabinol (THC) in blood using SPE and LC/MS/MS'. Together they form a unique fingerprint.

Cite this