Showing papers by "George G. Guilbault published in 1982"

Immobilized enzymes as analytical reagents.

Abstract: Immobilized enzymes are becoming increasingly popular as analytical reagents because of their reusability, stability, and sensitivity to many inhibitors that would seriously interfere in assays using soluble enzymes. In this article, some of the kinetic and catalytic effects of immobilized enzymes in analysis will be discussed. The shift of the activity-pH profile curves on immobilization, the changes in temperature dependence. the inhibitor constants (K1). Michaelis constants (Km), and the maximum velocity (Vmax). plus others, will be discussed. Finally, the use of these immobilized enzymes in fluorometric and electrochemical monitoring systems will be shown, and the future of these reagents in various areas will be discussed. A survey of enzyme electrodes will be presented as an example of the use of immobilized enzymes. Application of immobilized enzyme technology to the assay of BUN, glucose, uric acid, amino acids, ethanol. and other metabolites will be discussed.

Detection of carbon monoxide in ambient air with a piezoelectric crystal

Abstract: Carbon monoxide is first reacted with mercuric oxide at 210 C to produce mercury vapour. The mercury vapour liberated is then adsorbed on the gold electrode of the piezoelectric crystal, thereby increasing the mass on the crystal and decreasing its frequency of vibration. The change of frequency is proportional to the amount of mercury present and is indicative of the carbon monoxide content of the air. Reversibility can be achieved by thermal desorption. By use of a reference stream, the background due to the thermal decomposition of mercuric oxide is compensated. The effect of moisture and interferences from other reducing gases can be eliminated by use of a precolumn. The detector is simple, inexpensive, and portable. Concentrations in the part-per-million and part-per-billion ranges can be detected by varying the sample size.