AN AMPEROMETRIC GLUCOSE SENSOR WITH COMBINED ENZYME LAYERS

An amperometric needle-type glucose sensor (1) consisting of a silver tube (cathode) and a platinum wire (anode) was developed. The sensor was provided with two enzyme layers (glucose oxidase (GOD) in cellulose acetate, catalase). The destructive influence of H,0, generated in the GOD layer could be minimized and the oxygen dependence of the analytical signal was improved

FORMALDEHYDE ANALYSIS BY AN ENZYMATIC FIA-SYSTEM

The method for formaldehyde analysis presented here is based on the enzymatical reaction of formaldehyde with the coenzyme nicotinamide adenine dinucleotide (NADt) by catalysis of the enzyme formaldehyde dehydrogenase (FADH). The enzyme is immobilized on an epoxy resin. Formaldehyde is measured by electrochemical detection of NADH, using a redox dye as mediator. The analysis is carried out ina Flow-Injection-Analysis System (FIA) with an electrochemical wall-jet detector

Potentiometric Immunoassay (PIA)- Mixed Potential Shift by an Antigen/Antibody Reaction

This paper presents a method for the direct potentiometric detection of a specific antigen/antibody reaction. The method is based on a principle called "modulation of a mixed potential" at an ionselective electrode (ISE). The ion-selective membrane of an ISE is covered with antibody resp. antigen molecules. A high sensitivity is obtained when the mixed potential is especially unstable which is in general the case if a mixed potential between cations andanionsis built up across the phase boundary ofthe ion-selective membrane towards the sample solution. If the antigen binds to its specific antibody, a directly detectable shift results in the mixed potential. If the "immunoelectrode" is completed by a reference electrode, the corresponding changes of the cell voltage vs. concentration of antigen resp. antibody follows a typical immunological calibration curve. Since no labeled antigen Tesp. antibody molecule is needed, the necessary ISE is simple to construct andthe instrumentation is quite teasonable, PIA will be a very attractive method

FIBEROPTIC BIOSENSOR FOR LACTATE WITH REDOX DYES AS COENZYME

In this paper an optical sensor is described wich is based on a new enzymatic methode for the determination of lactate. The enzyme used in this reaction is cytochrome bo, which is able to take redox dyes as electron acceptors. The decolourization of the dye gives information aboutthe lactate concentration