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Table 1 Coded independent variables used in CCRD design

From: Effects of temperature, time, and solvent ratio on the extraction of phenolic compounds and the anti-radical activity of Clinacanthus nutans Lindau leaves by response surface methodology

Symbol

Independent variables

Coded level

−1.68

−1

0

+1

+1.68

A

Extraction temperature (°C)

53.18

60.00

70.00

80.00

86.82

B

Extraction time (min)

66.36

80.00

100.00

120.00

133.64

C

Solvent ratio (water: ethanol), v/v%

63.18:36.82

70:30

80:20

90:10

96.82:3.18