Blank measurements bypassing the reactor were performed before each separate run to observe the pump or reactant feed background before injecting the sample into the reactor. Those measurements could directly be used to calculate the reactant 1 conversion in the subsequent reactor runs (Fig. ). Additionally, washing steps were conducted after each run to flush the respective reactant. As proof of principle, the effect of varying reactant 1 concentrations of hydrogen peroxide, sodium vanadate, and ammonium bromide on the examined biocatalytic bromination reaction was screened (detailed reactant compositions in the ESI at Table ). A higher hydrogen peroxide proportion (R2: 1.75 eq. H2O2 and 2 eq. NH4Br instead of initial R1: 1.0 eq. and 7.0 eq. mM, respectively) resulted in a higher conversion and product 2 area fraction. However, this led to byproduct formation, which was assigned as an oxygenated species S2-S5 (not shown here; discussion in ESI section S4.3). Further increasing the vanadium cofactor (R3: 2 eq. Na3VO4 instead of initial R2: 1 eq.) or the ACN fraction (R4: 70% ACN instead of initial R2: 40%) led to less total reactant conversion, which can be attributed to reduced byproduct S2-S5 formation. At the same time, the product 2 signal remained consistently high. As expected, the last microreactor, containing only a halfpacked column (R5), resulted in less total conversion and product 2 formation. Overall, the automated multi-reactor screening platform demonstrated the capability for efficient and rapid screening of various reaction samples with different compositions, allowing for fast data generation and optimisation of biocatalytic transformations or as validation feedback for enzyme optimization processes (automation and sequencing details, as well as additional experimental details, can be withdrawn from the ESI at section S5.2).