Preparation of calibration standards and quality control (QC) samples
A calibration curve was generated from different standard concentrations that were prepared by spiking a small volume of the working solution (not more than 5% of the total volume) into blank human plasma or urine to obtain twelve final concentrations ranging between 0.98 and 1000.00 ng/mL for each analyte. Quality Control (QC) samples were also prepared by using the same method as the calibration standards; with concentrations of 2.50, 500.00, and 900.00 ng/mL for low (LQC), medium (MQC), and high (HQC) concentrations, respectively. These spiked plasma samples (calibration standards and QC samples) were then similarly extracted following the sample preparation protocol with the addition of 50.00 ng/mL of IS.