Quantitative analysis of samples using a 5PL standard curve fit plotted on log-log axes to calculate concentrations. This protocol is suitable for enzyme-linked immunosorbent assays measured on 96-well (12x8) microplates. This analysis optionally includes a background correction step. If a blank group is included on the selected layout, the mean of the blank replicates is first subtracted from the raw data measurements (the corrected values are then used in the fit). The standard data points (concentration vs. measurement) are plotted and the selected curve is fitted through the standard data points. The concentrations of the samples are determined from the fit with any specified dilution factors applied. Samples outside the range of the standards are highlighted in yellow. The %CV of the final concentration replicate values are computed.