Four Parameter Logistic Fit
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Quantitative analysis of samples using a
Four Parameter Logistic Fit (4PL) suitable for
symmetrical sigmoidal data.
All samples are first corrected by the mean of the blank group measurements. The standard data points are plotted (concentration vs. corrected measurement) and a
Four Parameter Logistic Fit (4PL) is made through these points. The concentrations of the unknown samples are determined from the fit. It is important to note that concentrations can only be determined for samples which fall within the range of the determined upper and lower asymptotes of the fit (the a and d parameters).