As an alternative to a simple linear baseline, usually guided by a part of the sweep where the faradaic current is zero (the range), I provide here a simple non-linear baseline, guided by both the range and by a part of the sweep where the faradaic current has reached a limiting value (the range), as illustrated in Figure . Note that if a ``swichy'' voltammogram is analyzed, the limiting current is that of the plateau, not the maximal (peak) current.
In Figure A, each pair of squares defines an interval, one in the region, and the other in the part of the voltammogram (empty and filled symbols, subscripts and , respectively). For both ranges, the average potentials , or , currents and slopes are measured.
In the range , a second order polynomial baseline ( ) is calculated so that (i) it goes through the points of coordinates () and ( ), and (ii) its slopes at these positions () match the values of . , , and , which define the polynomial baseline, and , are therefore the unique solution of the linear set of equations:
In the ranges and , the baseline is linearly extrapolated.
Christophe Leger 2009-02-24