Calculation of EF, ER and RR
In this study, the enrichment factor (EF) was calculated as the ratio
between the analyte concentration in the eluent phase and the initial
sample solution, which was shown as follows:
EF C
C = elu
0 (1)
The extraction recovery (ER) was used to express the extraction
performance during the optimization of different experimental parameters.
ER was defined as the percentage of the total analyte amount
(n0) that was extracted into the eluent phase (nelu):
ER n
n
C V
C V
% = × 100% = ×
× × 100% elu elu elu
0 0 0 (2)
where Celu is the analyte concentration in the eluent, C0 is the initial
analyte concentration in the sample, and Velu and V0 refer to the
volume of the organic phase and the volume of the sample solution,
respectively. In practice, Celu was calculated from the external calibration
curves that were drawn for the peak areas measured versus the
concentrations of the analytes in the standard solution.
The relative recovery (RR) was used in the analysis of the water and
tea beverage samples. The formula for RR is shown in Eq. (3):
RR C C
C
% = − × 100% detection real
add (3)
where Cdetection, Creal, and Cadd are the detected concentration of the
analyte in the sample after the addition of a known amount of standard
to the real sample, the concentration of analyte in the real sample, and
the concentration of the spiked known amount of standard in the
sample, respectively