Abstract: A stabilized urease solution is disclosed comprising water, buffering agents, a bacteriostat, chelating agent, polyhydroxy organic compound and urease. The preferred buffering agents are selected from low conductivity Zwitterionic buffer salts, such as N-2-hydroxyethyl-piperazine-N'-2-ethanesulfonic acid, triethanolamine, tris(hydroxymethyl)aminomethane, diethanolamine, aminomethyl propanol and mixtures thereof.

Abstract: A multi-reagent for use in stabilized liquid form is prepared containing three separate reagent solutions which can be combined in proper amounts to form a working composition for a biological diagnostic determination. The first reagent solution contains an aqueous vehicle, organic solvent and coenzyme; the second reagent solution contains an aqueous vehicle, organic solvent, enzyme and substrate; and the third reagent solution contains an aqueous vehicle, buffering agent and an additional component such as a sulphydryl compound.

Abstract: Stabilized liquid enzyme and coenzyme compositions are prepared for use in biological diagnostic determination of glucose. In one embodiment a composition is prepared containing in admixture an aqueous vehicle, a nicotinamide-adenine dinucleotide coenzyme, a nucleotide, an enzyme including hexokinase and/or glucose-6-phosphate dehydrogenase and an organic solvent to stabilize the enzyme, coenzyme and nucleotide. The compositions have a pH of 6.0 to 8.5 and may contain a bacteriostat such as an azide compound. A preferred organic solvent is a polyol. In an alternative embodiment, a two reagent liquid enzyme and coenzyme composition is prepared wherein the enzyme is stabilized in one solution and the coenzyme and nucleotide stabilized in another solution, and the two solutions combined when used. In the enzyme-containing solution, an ammonia salt can be used as an alternative to the organic solvent to stabilize the enzyme.

Abstract: Stabilized liquid enzyme and/or coenzyme compositions are prepared for use in biological diagnostic determinations. The compositions contain an enzyme and/or coenzyme, an organic solvent such as a polyol and an aqueous vehicle. The compositions may also contain a polymer and a bacteriostat. The compositions exhibit excellent shelf life and the container in which a composition is stored can be repeatedly opened for use without any substantial degradation of the enzyme and/or coenzyme.

Abstract: Labile coenzymes, such as reduced nicotinamide-adenide dinucleotide (NADH.sub.2), are stabilized by forming a composition of the coenzyme with an organic solvent such as 1,2 propanediol in the presence of at least 1% by volume of a solid, inert hygroscopic agent such as 10% by volume of a molecular sieve material. The stabilized composition contains less than 0.5% water, shows excellent shelf life and a container in which the composition is stored may be repeatedly opened for use without degradation of the labile coenzyme such as the labile NADH.sub.2.

Abstract: A stabilized liquid phosphate containing diagnostic composition and generally a phosphate containing substrate used in the determination of enzymes such as alkaline phosphatase and acid phosphatase. The composition actually includes a buffer composition containing a magnesium ion for activation of the enzyme and a substrate composition, which are mixed at time of determination. The buffer composition is of the proper pH so that when the buffer composition and the substrate composition are mixed, the resultant mixture will adopt the pH of the buffer composition. The stabilizer which is employed is one that will prevent hydrolysis of the phosphate from the organic substrate. Effective stabilizers include phenol and phenolic compounds and imidazole and nitro alaphatic compounds having from one through six carbon atoms.