Indigo carmine is a commonly used industrial blue dye. To determine its concentration in a commercially available food dye composed of a mixture of indigo carmine and D-glucose, this paper characterizes it through (ATR, KBr) FTIR micro-Raman as well as UV/Vis and clock: Briggs–Rauscher (BR) oscillatory reaction methods. The indigo carmine was detected in the bulk food dye only by applying micro-Raman spectroscopy, indicating a low percentage of the indigo carmine present. This research provides an improvement in the deviations from the experimental Raman spectrum as calculated by the B97D/cc-pVTZ level of theory one, resulting in a better geometrical optimization of the indigo carmine molecule compared to data within the literature. The analytical curves used to determine indigo carmine concentrations (and quantities) in an aqueous solution of food dye were applied by means of UV/Vis and BR methods. BR yielded significantly better analytical parameters: 100 times lower LOD and LOQ compared to commonly used UV/Vis. The remarkable sensitivity of the BR reaction towards indigo carmine suggests that not only does indigo carmine react in an oscillatory reaction but also its decomposition products, meaning that the multiple oxidation reactions have an important role in the BR’s indigo carmine mechanism. The novelty of this research is the investigation of indigo carmine using a clock BR reaction, opening new possibilities to determine indigo carmine in other complex samples (pharmaceutical, food, etc.).

Whether the bulk crystallographic phase determines the H₂O₂ reactivity of oxide nanopowders has direct implications for catalyst design. Three glycine–nitrate-derived CoMoO₄ nanopowders—as-synthesized, calcined at 450 °C (both β-CoMoO₄ by XRD), and calcined at 1000 °C (α-CoMoO₄)—were studied by ATR-FTIR spectroscopy, the Briggs–Rauscher (BR) oscillatory reaction, cyclic voltammetry (CV), and electrochemical impedance spectroscopy. Deconvolution of the Mo–O stretching region with a uniform Voigt line shape resolves octahedral (α-type) and tetrahedral (β-type) Mo⁶⁺ components in both β-classified powders, indicating short-range coordination heterogeneity not detected by XRD. In the BR reaction (n = 3), the 450 °C powder suppresses oscillations at ≤0.002 g, whereas the as-synthesized powder still oscillates at 0.040 g (slope of the τ_osc decrease is 5172 ± 406 s g⁻¹), and the bulk-α 1000 °C powder is about four times less active per gram than the as-synthesized powder. CV supports the highest activity of the 450 °C powder. A semi-quantitative descriptor, Φ = ρ_α × S_BET, combining the FTIR α-type band-area fraction with the BET surface area, identifies the most active powder but does not discriminate between the two less active ones. Within this series, bulk phase identity alone does not predict peroxidase-mimetic activity.