The capillary plasma jet used in this study was identified as promising source for H2O2 generation and H2O2 transfer into liquid samples. The radio frequency (RF)-driven (13.56 MHz) atmospheric pressure capillary plasma jet was used as described before but with inner capillary (Hilgenberg, Germany) dimensions of 4.56 mm × 0.88 mm × 100 mm. The electrodes (itec Automation & Laser AG, Germany) had a width and length of 4 mm and 40 mm, respectively, resulting in a plasma volume of 4 mm × 0.88 mm × 40 mm. The wall thickness of the capillary was 0.22 mm, leading to a distance of 1.32 mm between the electrodes. Plasma was operated at a plasma power of (6.0 ± 0.6) W. The gas flow (2 slm He) was split and partially routed through a bubbler with cooled deionized water to enrich the feed gas with water molecules. The distance between the nozzle of the capillary jet and the sample was approx. 16 mm and the plasma zone ended 10 mm in front of the nozzle exit of the capillary. Plasma-driven biocatalysis was performed as described previously. In short, 150 mg protein-loaded beads were transferred to a rotating bed reactor (build in-house, dimensions: ∅ 2 cm × 0.7 cm). The reactor was placed in a vessel filled with 5 ml potassium phosphate buffer (100 mM, pH 7) containing 50 mM ethylbenzene (ETBE). Plasma treatment was performed for up to 40 min, while every 5 min 150 µl sample were withdrawn for gas chromatography-based quantification of product as described elsewhere. After biocatalysis, residual activities of protein-loaded beads were determined. To this end, beads were recovered from the rotating bed reactor and washed thrice with potassium phosphate buffer. Enzyme activity was determined as described for the unimmobilized enzyme but in a total volume of 1 ml. To ensure sufficient substrate supply, samples were incubated shaking during turnover. For a total of ten minutes reaction time, every two minutes aliquots of 100 µl were removed and measured at a wavelength of 405 nm using a microplate reader (Biotek Epoch, Germany). Enzyme activity was calculated based on the linear slope of the kinetic.