Abstract: A method is disclosed for the quantitative determination of 1,4-dihydronicotinamide adenisne dinucleotide (NADH) in solution. The method comprises contacting the NADH-containing solution with an activated carbon electrode, maintaining the carbon electrode at a controlled, fixed potential effective to cause oxidation of NADH at the electrode surface, and measuring the current output from the carbon electrode, wherein there is used a noble metal containing preferably a platinized or palladized activated carbon electrode comprising a porous, heterogeneous, resin-bonded layer of activated carbon or graphite particles comprising the finely divided noble metal preadsorbed thereon and bonded together with a natural or synthetic resin binder, preferably a hydrophobic resin such as polytetrafluoroethylene.

Abstract: Enzyme electrodes are disclosed which are capable of responding amperometrically to the catalytic activity of the enzyme in the presence of its respective substrate and comprising the enzyme immobilized or adsorbed onto the surface of an electrically conductive support member which consists of or comprises a porous layer of resin-bonded carbon or graphite particles, said particles having intimately mixed therewith, or deposited or adsorbed onto the surface of the individual particles prior to bonding to form said layer, a finely divided platinum group metal, thereby to form a porous, substrate layer onto which said enzyme is adsorbed or immobilized and comprising a substantially heterogeneous layer of resin-bonded carbon or graphite particles, with said platinum group metal dispersed substantially uniformly throughout said layer.

Abstract: In operation of a microbial fuel cell it has been found that improved efficiency results if the microbes are kept `hungry`, i.e. the cell is run under conditions of fuel supply and load such that electrical output is dependent on fuel concentration, rather than as is conventionally the case being run under excess fuel so that power output is concentration independent.A method and apparatus are described to enable fuel cells to be run under energetic or coulombic efficiency control.