Essential Oil Extracted from Cymbopogon citronella Leaves by Supercritical Carbon Dioxide: Antioxidant and Antimicrobial Activities

Table 3

ANOVA results for the quadratic equation for the extraction yield of essential oil.

Term	Freedom degrees	Sum of squares	Mean square	F value	Pr > F
Model	14	0.564475	0.04032	35.08174	<0.0001
X1	1	0.002408	0.002408	2.095468	0.173353
X2	1	0.000533	0.000533	0.464048	0.508671
X3	1	0.009633	0.009633	8.381873	0.013447
X4	1	0.015408	0.015408	13.40665	0.003257
X1  ·  X1	1	0.016875	0.016875	14.68278	0.002388
X1 · X2	1	0.007225	0.007225	6.286405	0.027545
X1 · X3	1	0.003025	0.003025	2.632024	0.130689
X1 · X4	1	0.003025	0.003025	2.632024	0.130689
X2 · X2	1	0.0147	0.0147	12.79033	0.003808
X2 · X3	1	0.000625	0.000625	0.543807	0.475032
X2 · X4	1	0.0081	0.0081	7.047734	0.020994
X3 · X3	1	0.472033	0.472033	410.7118	<0.0001
X3 · X4	1	0.0081	0.0081	7.047734	0.020994
X4 · X4	1	0.644342	0.644342	76.92326	<0.0001
Pure error	12	0.013792	0.001149	No clear	No clear
R^2 = 0.9761; Adj. R^2 = 0.9483; CV = 3.25%; Adeq. precision = 18.571