Measurement of UV/VIS-absorption spectra of photochemically active solutions in continuous flow

Knowledge of UV/VIS absorption spectra is crucial for designing photochemical processes, but measurements become challenging for systems with fast photoreactions such as photochlorinations. Such challenges include the change in concentration during measurement, evolution of gaseous products, safety concerns as well as the requirement to avoid contact with moisture or oxygen. To overcome these points, a continuous flow method is developed for UV/VIS measurements. The method is applied to the determination of absorption spectra of chlorine dissolved in different organic solvents and the general feasibility is proven. Compared to non-aromatic solvents, the gathered data reveal significant hypsochromic and hyperchromic effects for aromatic solvents.