In PR.Panta Analysis, two additional output parameters are calculated from the turbidity: The turbidity average and the inflection increase. Both can serve as a measure of total aggregation in a sample and are described in more detail below.

The turbidity average is simply the average of all data points after the inflection point. The earlier aggregation starts, and the higher the absolute value of the turbidity signal measured, the higher the turbidity average is going to be.

The inflection increase takes into account two characteristics of the turbidity signal: the steepness of the slope at the inflection point (IP), which indicates how fast the aggregation process happens, and the total amplitude. The steeper the slope and the higher the amplitude, the higher the inflection increase is going to be.

Note that the slope at the IP is also output by PR.Panta Analysis software as a separate parameter.

The images below illustrate how the inflection increase is calculated. First, a baseline is estimated and the slope at the inflection point is calculated (purple lines). The intercept of baseline and slope is determined. The x-distance between intercept and IP is calculated (x). The points IP-x and IP+x are located (yellow dotted lines). Then, the y-distance is calculated between these points and the IP (green dotted lines; y1 and y2). The Inflection Increase then is the distance between the midpoints of y1 and y2.

Figure: The first panel shows exemplary turbidity data. The boxed part of the image is shown in closeup view in the second panel.