Determination of Total Selenium in Infant Formulas: Comparison of the Performance of FIA and MCFA Flow Systems

Table 3

Central composite experimental design, 4 variables and 3 levels.

Experiment	Flow rate HCl (mL min^−1)	Flow rate NaBH4 (mL min^−1)	HCl% (v/v)	NaBH4 (% (m/v)) in NaOH 0.05%	Absorbance Se(IV) 50 μg · L^−1 (𝑛=3) dissolution
1	1.3	1.7	5	0.1	0.076
2	1.3	1.7	5	0.5	0.069
3	1.3	1.7	30	0.1	0.081
4	1.3	1.7	30	0.5	0.070
5	1.3	4.5	5	0.1	0.065
6	1.3	4.5	5	0.5	0.043
7	1.3	4.5	30	0.1	0.066
8	1.3	4.5	30	0.5	0.044
9	2.8	3.7	15	0.2	0.167
10	5.9	1.7	5	0.1	0.222
11	5.9	1.7	5	0.5	0.228
12	5.9	1.7	30	0.1	0.205
13	5.9	1.7	30	0.5	0.200
14	5.9	4.5	5	0.1	0.162
15	5.9	4.5	5	0.5	0.112
16	5.9	4.5	30	0.1	0.170
17	5.9	4.5	30	0.5	0.115