Effect of Temperature and Duration Time of Maceration on Nitrate Content of Vernonia cinerea (L.) Less.: Circumscribed Central Composite Design and Method Validation

Table 1

Factors and responses of model conditions of circumscribed central composite experimental design.

Condition	Factors				Responses
	Temperature		Time		Yield of the extraction (%)	Nitrate content (%)
	Coded	Actual (°C)	Coded	Actual (min)
1	-1	48.8	-1	17.3	8.4	0.315±0.008
2	1	91.2	-1	17.3	10.4	0.368±0.000
3	-1	48.8	1	52.7	10.0	0.372±0.000
4	1	91.2	1	52.7	15.2	0.486±0.000
5	-√2	40.0	0	35.0	6.0	0.175±0.000
6	√2	100.0	0	35.0	16.6	0.578±0.000
7	0	70.0	-√2	10.0	7.4	0.258±0.001
8	0	70.0	√2	60.0	13.6	0.536±0.001
9	0	70.0	0	35.0	11.4	0.467±0.000
10	0	70.0	0	35.0	11.4	0.402±0.000