van Holde - Weischet Tutorial

Speed too low/experiment too long

Figure 20:Single component system. Scans drawn in red do not have a stable plateau and interference from back-diffusion distorts the plateau absorbance near the bottom of the cell. These scans should not be included in the analysis. If possible, the speed should be increased and the scan delay should be reduced, if possible).

Figure 21: van Holde - Weischet analysis of data including scans drawn in red. The extrapolation plot clearly shows a diagnostic identifying the scans that should be excluded from the analysis. All scans which do not have a stable plateau display the loss of material in the upper boundary fractions and cause poor correlation in the linear fits, resulting in incorrect extrapolations to the intercept. After excluding inappropriate scans, the data reverts to nearly perfect correlation (see below).

Figure 22: van Holde - Weischet analysis of data excluding scans drawn in red. The extrapolation plot shows a good correlation for all scans across the entire boundary.