Table 1 Regression and validation data for the determination of FEX and PSE by the proposed method

Wavelength (nm)

286

294

Linearity range (ng/mL)

100–1500

50–1000

LOD (ng/mL)

24.15

12.88

LOQ (ng/mL)

73.49

39.21

Slope

0.0377

0.0623

Intercept

9.6551

8.8644

Coefficient of determination (r²)

0.9995

0.9994

Accuracy (%R)^a

99.13

98.46

Precision (RSD)^b

 Repeatability

1.369

0.493

 Intermediate precision

1.012

1.207

Robustness (%R ± RSD)

 Δλ (± 1 nm.)

100.63 ± 0.926

99.20 ± 1.017

 pH (± 0.1)

99.98 ± 1.066

99.82 ± 1.314

 Buffer volume (± 0.1 mL)

100.89 ± 0.878

100.12 ± 0.950