Fourier transform infrared detection in miniaturized total analysis systems for sucrose analysis

In this work, a now system containing a micromachined lamella-type porous silicon reactor and a novel mid-IR fiber-optic now cell were used for the enzymatic determination of sucrose in aqueous solution, The method relies on the enzymatic hydrolysis of sucrose to fructose and glucose catalyzed by beta-fructosidase and on the acquisition of FT-IR spectra before and after complete reaction. beta-Frudosidase was covalently bound to the porous silicon surface of the channels in the microreactor, The porous silicon was achieved by anodization of the silicon reactor in a HF/ethanol mixture. For the measurement of small amounts of aqueous solution, a miniaturized now eel was developed which consisted of two AgClxBr1-x fiber tips (diameter, 0.75 mm) coaxially mounted in a PTFE block at a distance of 23 mu m. The flowing stream was directed through the gap of the two fiber tips which sewed to define the optical path length and to bring the focused mid-IF radiation to the place of measurement. Using this construction, a probed volume of similar to 10 was obtained, The calibration curve was linear between 10 and 100 mmol/L sucrose, Furthermore, the potential of this method was demonstrated by the analysis of binary sucrose/glucose mixtures showing no interference from glucose and by the successful determination of sucrose in real samples.