Thermooptical flow-injection determination for hydrogen peroxide based on an enzymic reaction heat-induced optical beam deflection

A novel thermooptical flow-injection method for hydrogen peroxide determination is proposed, based on immobilized enzymic (catalase) reaction heat-induced optical beam deflection. A glass tube, whose one end is attached with a thin gold film on which the catalase is immobilized, is used as a reaction cell. The reaction cell is immersed into a CCl4 phase where a probe beam is passed through. Hydrogen peroxide solution is injected into the stream of sodium phosphate buffer solution (pH 7.4) flowing into the reaction cell. The reaction heat of the decomposition reaction of H2O2 catalyzed by the immobilized catalase induces a deflection of the probe beam. The immobilization of catalase by crosslinking with bovine serum albumin is optimized to obtain a maximum beam deflection signal. The deflection signal is linear over the concentration range of 0.025-0.5 mol 1−1 (40 μl injected) for H2O2 and the detection limit is ca. 0.025 mol 1−1. This thermooptical flow-injection detection system has good stability and reproducibility. The noise source is discussed and the improvements on the experimental setup are also discussed.