Table 7 Results of the method validation

Linearity

Linearity range

60–360 μg/mL

40–140 μg/mL

40–140 μg/mL

20–120 μg/mL

Correlation coefficient (R²)

0.999

0.999

0.998

0.998

Regression equation

y = 3276x – 44,583

y = 5226x – 95,804

y = 5089x – 90,670

y = 3500x + 20,863

Sensitivity

LOD (μg/ml)

1.389

0.082

0.622

0.772

LOQ (μg/ml)

4.167

0.246

1.866

2.316

Precision (% RSD of peak area)

Intra-day precision

0.303

0.953

0.893

0.836

Inter-day precision

0.566

0.99

0.92

0.956

Robustness (% RSD of peak area)

Flow rate (± 0.1 ml/min)

0.63

0.336

0.163

1.13

pH (± 0.2)

0.896

0.406

0.16

1.32

Organic phase (± 1%)

0.62

0.34

0.15

1.2

Wavelength (± 2 nm)

0.623

0.37

0.303

1.53

System suitability

Retention time (min)

3.91

7.15

11.94

2.96

Theoretical plate number

6194.8

4899.29

2113.99

3940.49

Tailing factor

1.24

1.10

1.13

1.26

Resolution

4.7

10.6

6.4

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