Abstract: Potentially irritant or allergenic test materials are incorporated into predetermined areas (12) of a temporary tattoo (30) which is applied to skin (31). After a few days the tattoo (30) is removed and the exposed skin is examined. Reddened areas (32,36) can be correlated with test materials that were present in overlying areas of the tattoo, e.g. by comparison with a map (40) and key.

Abstract: An analyte is determined electrochemically indirectly. In a first step an oxidase and an oxidisable substrate, one of which is the analyte or derived therefrom, interact and generate hydrogen peroxide. In a second step a peroxidase (especially horse-radish peroxidase) reduces the hydrogen peroxide and concomitantly oxidises a mediator, preferably 2,2?-azino-bis(3-ethyl=benzthiazoline-6-sulfonic acid, ABTS) to an oxidised form (ABTSOX). The oxidised mediator is then reduced at an electrode and the consequent current is measured. A preferred sensor format uses a carbon electrode screen-printed onto a substrate and overlaid with one or more layers containing the enzymes and other components.

Abstract: Electrochemical heavy metal analysis includes a printed electrode having a layer of a mercury compound or salt supported thereon. The compound or salt is reduced to metallic mercury in use of the electrode. The mercury layer may comprise a layer of hydroxyethyl cellulose or other permeable polymer.