Table 2 Regression and validation parameters of the current HPLC method for the determination of EMP, LIN, and MET along with MEL and CYG as MET potential official impurities

Linearity range

0.2–8.0

 µg/mL

0.3–9.0

 µg/mL

1.0–250.0

 µg/mL

1.0–100.0

 µg/mL

1.0–100.0

 µg/mL

Slope

116.407

38.804

183.342

8.262

91.431

Intercept

-3.772

-1.964

-17.832

0.492

-14.033

Correlation coefficient (r)

0.9999

0.9999

0.9999

0.9999

0.9999

LOD^a

0.05

0.09

0.19

0.2

0.1

LOQ^a

0.15

0.27

0.58

0.9

0.8

Precision

% RSD

Intra-day^b

0.438

0.311

0.621

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Inter-day^c

0.212

0.540

0.275

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