Table 2 Analyses of variance for the response surface quadratic model to optimize extraction parameters of lupeol and stigmasterol

Model

91.27

9

10.14

13.61

0.0002

92.21

9

10.25

18.19

< 0.0001

x₁-Solvent

5.24

1

5.24

7.04

0.0242

39.86

1

39.86

70.76

< 0.0001

x₂-Temperature

0.1351

1

0.1351

0.1814

0.6792

27.18

1

27.18

48.26

< 0.0001

x₃-Ultrasonication time

2.33

1

2.33

3.13

0.1073

0.0762

1

0.0762

0.1353

0.7207

x₁ x₂

5.53

1

5.53

7.42

0.0214

3.30

1

3.30

5.86

0.0361

x₁ x₃

0.1219

1

0.1219

0.1637

0.6943

0.6098

1

0.6098

1.08

0.3226

x₂ x₃

19.20

1

19.20

25.78

0.0005

1.98

1

1.98

3.52

0.0900

x₁²

33.96

1

33.96

45.59

< 0.0001

4.48

1

4.48

7.95

0.0182

x₂²

36.32

1

36.32

48.75

< 0.0001

11.63

1

11.63

20.65

0.0011

x₃²

1.48

1

1.48

1.98

0.1892

1.67

1

1.67

2.96

0.1162

Residua

7.45

10

0.7449

5.63

10

0.5633

Lack of fit

1.64

5

0.3277

0.2819

0.9045

3.36

5

0.6719

1.48

0.3394

Pure error

5.81

5

1.16

2.27

5

04547

Cor (Total)

98.72

19

97.84

19