. 2023 Oct 13;9(10):e20967. doi: 10.1016/j.heliyon.2023.e20967

Table 2.

Experimental design (three levels–three variables) using a mixture of diluted acids as the extractant.

Experiment	HNO₃(mol L⁻¹)	HCl (mol L⁻¹)	Time (min)	%R (Fe)	%R (Mn)
1	0.7	0.6	10	82.5	108
2	0.7	0.6	20	81.5	113
3	1.4	1.2	15	83.6	114
4	2.25	2.0	10	78.9	102
5	2.25	2.0	15	70.2	105

%R: mean recovery percentage after analysis of the bovine muscle CRM (n = 6 replicates of each experiment) [31].