Table 1.

Calibration curve parameters. The first two columns list the average parameters and standard deviation (σ) for each set of three calibration lines obtained at the University of Murcia (UMU) and Stockholm University (SU). The third column lists the parameters of the calibration line fitted to all data points under the constraint of passing through the average value at 0 NAR%.

Fitting Parameters	UMU	SU	All Data Points
	Mean ± σ
Best-fit values
Slope *	0.030 ± 0.002	0.031 ± 0.001	0.029
Y-intercept	0.145 ± 0.009	0.146 ± 0.008	0.152
Goodness of Fit
R2 **	0.978 ± 0.007	0.982 ± 0.019	0.973

* Slope units are NAR%⁻¹, ** R², coefficient of determination.