However, due to its larger FWHM, its λ peak determination results in a significantly higher noise, σ control , of 0.08 nm (Supplementary Figure ), which ultimately leads to a LoD of 1.5 ppm, nearly an order of magnitude higher than the detection limit of its array sensor counterpart (Fig. ). This comparison accentuates the critical impact of the narrow FWHM, here engineered through the use of optimized SLRs, for resolving Δλ peak signals at low concentrations.