Abstract: A novel apparatus is disclosed for the alternate filling and evacuation of all wells simultaneously of a multi-well microplate. The apparatus consists of a flat, horizontally disposed distribution head comprised of an upper and a lower chamber formed by these parallel plates, with a rectangular array of tubes passing through the lower of the three plates such that two tubes are aligned with each well of a microplate, one for filling and the other for evacuation. The filling tubes and evacuation tubes extend below the lower plate for unequal distances, the evacuation tubes being the more extended. All filling tubes communicate with one of the two chambers in the distribution head, while all evacuation tubes communicate with the other.

Abstract: A test system having an extended range of measurement and a corresponding procedure for the determination of substances in liquids contains several enzymes or enzyme systems together which, independently of one another, react directly or indirectly with the substance to be determined. On adding the test system to the sample solution, various final products are produced which can be distinguished analytically and evaluated by measurement techniques or visually. For example, glucose can be determined over a wide range of concentrations using a combination of an NAD-dependent dehydrogenase and a non-NAD-dependent dehydrogenase.

Abstract: A material and method for promoting the growth of anaerobic bacteria which includes a nutrient media containing a hydrogen donor and sterile membrane fragments of bacteria having an electron transfer system which reduces oxygen to water. Dissolved oxygen in the medium is removed by adding the sterile membrane fragments to the nutrient medium and holding the medium at a temperature of about 10.degree. to about 60.degree. C. until the dissolved oxygen is removed.