Table 2
RCCD consisting of three experimental factors in coded and actual levels with experimental results
Formulation	Coded independent variables			Actual independent variables			Dependent variables
	X1	X2	X3	X1	X2	X3	EE (%)	Mean size
1	1	1	1	10	5.2	0.42	36.96	381.2
2	1	1	−1	10	5.2	0.18	28.12	321.1
3	1	−1	1	10	2.8	0.42	42.74	510.2
4	1	−1	−1	10	2.8	0.18	41.09	770.2
5	−1	1	1	4	5.2	0.42	49.08	426.3
6	−1	1	−1	4	5.2	0.18	44.67	371.9
7	−1	−1	1	4	2.8	0.42	61.98	806.7
8	−1	−1	−1	4	2.8	0.18	54.10	1,216.6
9	+1.682	0	0	12	4	0.3	20.14	420.6
10	−1.682	0	0	2	4	0.3	60.50	790.1
11	0	+1.682	0	7	4	0.3	32.38	362.7
12	0	−1.682	0	7	2	0.3	50.14	980.1
13	0	0	+1.682	7	4	0.5	47.22	522.2
14	0	0	−1.682	7	4	0.1	32.19	539.8
15 to 20	0	0	0	7	4	0.3	37.38	471.1

n = 3. EE, entrapment efficiency; RCCD, rotatable central composite design; X₁, duration time of homogenization; X₂, agitation speed of homogenization; X₃, volume ratio of organic solvent phase to external aqueous phase.

Sun et al. Nanoscale Research Letters 2012 7:359   doi:10.1186/1556-276X-7-359