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Table 3 Matrix effects, absolute recovery and process efficiency for Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD), using dried oral fluid spots (DOFS) and weak anion exchange and salt (WAX-S) tips extraction

From: Study of Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD) extraction FROM dried oral fluid spots (DOFS) and LC–MS/MS detection

Drug Matrix Effects*
(%)
CV
(%)
Absolute Recovery* (%) CV Process Efficiency *
(%)
CV
(%)
THC (N = 10)
DOFS
Low (12 ng/mL) 98.7 15.6 23.8 14.2 23.5 19.3
High (50 ng/mL) 80.3 17.3 25.3 13.9 20.3 20.7
WAX-S tips
Low (12 ng/mL) 92.4 6.8 90.7 6.2 83.8 4.0
CBD (N = 10)
DOFS
Low (12 ng/mL) 75.2 18.5 24.8 18.0 18.6 23.9
High (50 ng/mL) 76.4 18.7 28.7 17.6 21.9 23.8
WAX-S tips
Low (12 ng/mL) 87.5 7.0 93.2 8.7 81.6 5.5
  1. *Matrix effects: accessed by dividing post-spiked average and neat samples, multiplied by 100;
  2. *Process efficiency: accessed by dividing pre-spiked samples by neat samples, multiplied by 100;
  3. *Recovery: calculated dividing pre-spiked samples by post-spiked samples, multiplied by 100