In eCerto: Statistical Tests for the Production of Reference Materials

Determining temperature-dependent reaction rates

The analyte values measured at $T_{min}$ are considered as stable and their mean is used as reference time point ($t=0$) for each temperature level $T_i$. When measured values are depicted relative to this mean, eCerto calculates and annotates the recovery and RSD for each $T_i$.

When the above ratios are log-transformed and the x-axis (time) is set to month, eCerto calculates the temperature-dependent reaction rates $k_{\mathit{eff}}(T)$ as the slope for each linear model of $T_i$.

$**Fig.S2** Calculation of degradation constant $k_{\mathit{eff}}$ for tested temperature levels$