Change of S versus abundance (left panels) and rotational velocity (middle panels), for each line of the solar spectra. The red lines represent the cubic spline fit performed over the data, and the vertical line shows the values where the minimum of S is reached. Right panels: line profiles, along with the final fit (red line) combining the instrumental profile, macroturbulence and rotational velocity. The horizontal black line around zero represents the residuals of the fit.