To further enhance the flexibility of the reactant feed, an autosampler was integrated as an automated tool for reactant feed variation, allowing for sequential screening of various manually prepared samples in an automated workflow. Due to the low reactor flow rate, the autosampler loop provided a constant reactant feed for multiple hours (40 µl, 0.2 µl/min, approx. 160 min reactant plug plateau). Thus, the platform can be used for testing different reaction conditions, which, combined with the selector valves, can be addressed to multiple different microreactors while minimising enzyme and reactant consumption. This functionality was demonstrated by sequentially testing five adjacent freshly packed reactor channels with different reaction mixtures in a single automated run, as shown in Fig. (all channels packed with CiVHPOHalo immobilised particles; last reactor only half-packed for comparison; sampling each 10 min, with each reactor run approx. 160 min and n=16 chromatograms; in total n=258 chromatograms, approx. 43 h).