2.5.4 Extraction recovery and matrix effect
The extraction recovery of TGC in serum and CSF was evaluated by comparing the peak area obtained from the blank serum and CSF spiked with analyte at low, medium and high concentrations with which obtained from standard solutions. Blank serum and CSF was processed as stated and then spiked with standard solution at low, medium and high concentrations to assess the matrix effect. The ratio of peak areas of TGC from spiked serum and CSF samples and pure TGC solution was defined as the matrix effect.