12. Calculate the concentration of the element (X) in the analyzed sample (mathematical and graphical).
Ion Concentration of standard solutions, mol/l
Parameter Analytical signal value
Si2 0.20 0.40 0.60 0.80 1.00 X
D 0.15 0.29 0.43 0.61 0.74 0.68;0.65;0.70; 0.71;0.64