Figure shows the results of the deconvolution process for the negolyte (a, c, d) and the posolyte (b, e, f). Some illustrative spectral fit examples are shown in (a, b) for SoC = 50% and C = 1.82 M. The dashed line represent the individual absorbance contribution of the pure compounds. The sum of these contributions yields the fitted curve (red) that is in good agreement with the experimental curve (black). For each spectrum, the minimization yields a set of predicted values(C P , SoC P ) that we compare to the true values (C T , SoC T ) that we know from our sample preparation (Section 2.1). Figure ) show the calibration curves of the negolyte (c, d) and the posolyte (e, f). These scatter plots compare the predicted values to the true values, with black dots representing results across all concentrations. Ideally, with 100% calibration accuracy, the predicted values would lie along the y = x blue line. Deviations from this line reflect calibration inaccuracies and measurement errors. To assess accuracy, the Root Mean Square Error (RMSE) was calculated for all concentrations, as detailed in Table . For the negolyte and the posolyte, the RMSE were respectively 1.54% and 3.25% for the SoC and 41 mM and 99 mM for the concentration. As should be expected, the positive calibration exhibits a higher error due to its non-linear spectral response and the presence of the complex. We also compared the errors obtained in this study with those from our previous work, where calibration was performed using continuous spectra collected with a commercial UV-Visible spectrometer. Although the errors from the continuous calibration were approximately half as large, this difference is relatively small, especially considering the leap from 6 to 3600 channels. This highlights the complexity of the relationship between calibration error, channel position, and number of channels. In other words, a discrete spectrum can hold substantial analytical information even with a limited number of channels. Nonetheless, considering the technological simplicity and cost-effectiveness of this system, these results are impressive and provide a strong proof of concept for developing multi-wavelength optical sensors for VRFBs.