The downscale of different unit operations for the biocatalytic carboligation of benzaldehyde and acetaldehyde catalyzed by benzoylformate decarboxylase from Pseudomonas putida was investigated. The reactor volume was reduced to 115 μ l thus enabling a substrate and enzyme saving by a factor of 52 in comparison to standard laboratory techniques. Additionally, the successful downscale of membrane based liquid-liquid contactors was shown, which allows, for example, the screening of solvents for extraction as well as the feed of a substrate. Here, comparable volumes as well as residence times were realized, enabling the integration of all three unit operations.

A concept for the determination of concentrations in microchannels using FT-IR spectroscopy in transmission is presented. The fundamental idea of spatially resolved measurements along several measuring points was implemented in a single-channel microreactor. Compared to existing microreactor setups for the analysis of fast chemical reactions or mixing processes, the presented concept enables longer residence times at appropriate resolution. Once steady-state conditions were reached in the reactor, mid-infrared spectra were collected at different locations. Information throughout the considered conversion range is available, which is of great importance to analyze inhibitory effects, next to the kinetic constants (vmax and KM). Therefore, this technology enables a rapid screening of (bio-)catalysts, substrate specificity and process conditions. In particular, the analysis of real substrates instead of model substrates and the possibility to follow side reactions and follow-up reactions during enzymatic catalysis open a broad field of application.

Monitoring the dispersed phase of an oil-in-water (O-W) emulsion by means of Fourier transform infrared (FTIR) spectroscopy is a challenging task, restricted to the continuous phase that is in contact with the FTIR probe. Nonetheless, real-time measurement and kinetic analysis by FTIR, including analysis of the dispersed, often non-polar phase containing substrates and/or products, is desirable. Enzymatic hydrolysis of sunflower oil was performed in an O-W emulsion. After separation of the oil phase by use of a newly developed μ-membrane module, infrared spectra were collected using an attenuated total reflectance (ATR) cell. Different chemometric models were calibrated using the partial least squares (PLS) algorithm. Online application of a chemometric model based on the FTIR spectra enabled real-time monitoring of free fatty acid concentrations in the oil phase.

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