FOURIER-TRANSFORM INFRARED DETECTION IN MINIATURIZED TOTAL ANALYSIS SYSTEMS FOR SUCROSE ANALYSIS

In this work, a now system containing a micromachined lamella-type por ous silicon reactor and a novel mid-IR fiber-optic now cell were used for the enzymatic determination of sucrose in aqueous solution, The me thod relies on the enzymatic hydrolysis of sucrose to fructose and glu cose catalyzed by beta-fructosidase and on the acquisition of FT-IR sp ectra before and after complete reaction. beta-Frudosidase was covalen tly bound to the porous silicon surface of the channels in the microre actor, The porous silicon was achieved by anodization of the silicon r eactor in a HF/ethanol mixture. For the measurement of small amounts o f aqueous solution, a miniaturized now eel was developed which consist ed 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 direc ted through the gap of the two fiber tips which sewed to define the op tical path length and to bring the focused mid-IF radiation to the pla ce of measurement. Using this construction, a probed volume of similar to 10 was obtained, The calibration curve was linear between 10 and 1 00 mmol/L sucrose, Furthermore, the potential of this method was demon strated by the analysis of binary sucrose/glucose mixtures showing no interference from glucose and by the successful determination of sucro se in real samples.