Matrix Nominal concentration (ng/mL) Analyte with matrix ions peak area ratio1 Analytepure solutions peak area ratio1 Normalized matrix factor1 Plasma 162.2 0.65± 1.43 0.76± 12.27 0.85 ± 1.43 973.2 0.69 ± 10.33 0.68± 2.72 1.02± 10.33 Hair 162.2 1.81± 5.83 1.39± 5.56 1.31± 5.83 973.2 1.53± 16.91 1.45± 7.46 1.06± 16.91 1Mean values ± %Coefficient of variation

Table 6: Matrix effect of citalopram in plasma and hair at two concentration levels.