Method of forming stabilized urease solutions
OwnerIvan E. Modrovichinventor
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Abstract
A stabilized urease solution is formulated by blending 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.
Claims17
A process for forming a stabilized urease solution comprising the steps of:
- (a) mixing a stabilizing amount of N-2-hydroxyethyl-piperazine-N'-2-ethanesulfonic acid and water which is substantially free of metal ions;
- (b) adding a bacteriostat to the mixture, which bacteriostat comprises an alcohol which is nondegradative to urease and is present in an amount sufficient to inhibit bacteria growth;
- (c) adding a chelating agent to the mixture for complexing any metal ions present in the mixture;
- (d) buffering the mixture to a pH range of from about 5 to about 9 by adding a buffering agent comprising a zwitterionic, low-conductivity compound selected from the group consisting of N-2-hydroxyethyl-piperazine-N'-2-ethanesulfonic acid, triethanolamine, tris(hydroxymethyl)aminomethane, diethanolamine, aminomethyl propanol and mixtures thereof, the amount of buffering agent being sufficient to maintain pH in the presence of ammonia formed from urea;
- (e) admixing with the mixture a polyhydroxy organic compound selected from the group consisting of glycerol, ethylene glycol, sorbitol, and propylene glycol;
- and
- (f) adding urease enzyme to the mixture to form a solution wherein the urease is effectively stabilized by the presence of the N-2-hydroxyethyl-piperazine-N'-2-ethanesulfonic acid, bacteriostat and the polyhydroxy organic compound.
A process for forming a stabilized urease solution comprising the steps of:
- (a) mixing a stabilizing amount of N-2-hydroxyethyl-piperazine-N'-2-ethanesulfonic acid and water which is substantially free of metal ions;
- (b) adding 2,4-dichlorophenol to the mixture in an amount sufficient to inhibit bacteria growth;
- (c) adding ethylenediaminetetraacetic acid to the mixture;
- (d) buffering the mixture to a pH of from about 6 to about 8 by adding triethanolamine, the total amount of buffer being sufficient to maintain pH in the presence of ammonia formed from urea;
- (e) admixing glycerol with the mixture;
- and
- (f) adding urease enzyme to the mixture to form a solution wherein the urease is effectively stabilized by the presence of N-2-hydroxyethyl-piperazine-N'-2-ethanesulfonic acid, 2,4-dichlorophenol and glycerol.
A process for forming a stabilized urease solution comprising the steps of:
- (a) mixing a stabilizing amount of N-2-hydroxyethyl-piperazine-N'-2-ethanesulfonic acid and water which is substantially free of metal ions;
- (b) adding a bacteriostat which is nondegradative to urease to the mixture in an amount sufficient to inhibit bacteria growth;
- (c) adding a chelating agent to the mixture for complexing any metal ions present in the mixture;
- (d) buffering the mixture to a pH range of from about 5 to about 9 by adding a buffering agent comprising at least one zwitterionic, low-conductivity compound, the amount of buffering agent present being sufficient to maintai pH in the presence of ammonia formed from urea;
- (e) admixing with the mixture a polyhydroxy organic compound;
- and
- (f) adding urease enzyme to the mixture to form a solution wherein the urease enzyme is effectively stabilized by the presence of N-2-hydroxyethyl-piperazine-N'-2-ethanesulfonic acid, bacteriostat and polyhydroxy organic compound.
A stabilized urease solution for analysis of urea which comprises an admixture formed by urease enzyme addition to an aqueous solution of a stabilizing amount of N-2-hydroxyethyl-piperazine-N'-2-ethanesulfonic acid, a bacteriostat non-degradable to urease enzyme present to inhibit bacteria growth, a chelating agent for complexing metal ions in the aqueous solution, at least one zwitterionic, low-conductivity compound, the amount of zwitterionic compound present being sufficient to provide a solution having a pH of from about 5 to about 9 and sufficient to maintain with the N-2-hydroxyethyl-piperazine-N'-2-ethanesulfonic acid a solution of pH in the presence of ammonia formed from urea, and a stabilizing amount of at least one polyhydroxy organic compound, said aqueous solution being substantially free of free metal ions.
A stabilized urease solution for urea analysis which comprises an admixture formed by urease enzyme addition to an aqueous solution of a stabilizing amount of N-2-hydroxyethyl-piperazine-N'-2-ethanesulfonic acid, 2,4-dichlorophenol to inhibit bacteria growth, ethylenediaminetetraacetic acid, triethanolamine in an amount sufficient to provide a solution pH of from about 6 to about 8 and sufficient to maintain pH in the presence of ammonia formed from urea, and a stabilizing amount of glycerol, said solution being substantially free of free metal ions.
A stabilized urease solution kit which comprises:
- (a) a reagent concentrate solution comprising distilled water, N-2-hydroxyethyl-piperazine-N'-2-ethanesulfonic acid, a chelating agent for heavy metal ions, a bacteriostat to inhibit bacteria growth, at least one zwitterionic low-conductivity buffering compound, a polyhydroxy compound, and urease;
- and
- (b) a diluent solution selected from distilled water and a solution of bacteriostat in distilled water, the reagent concentrate and diluent solution when combined containing sufficient buffering compound to provide a solution pH of from about 5 to about 9 in the presence of ammonia formed from urea, the N-2-hydroxyethyl-piperazine-N'-2-ethanesulfonic acid, bacteriostat and polyhydroxy compound cooperating to stabilize the urease, both in the reagent solution and when the reagent and diluent solutions are combined.
A stabilized urease solution kit which comprises:
- (a) a reagent concentration solution comprising distilled water, N-2-hydroxyethyl-piperazine-N'-2-ethanesulfonic acid, 2,4-dichlorophenol in an amount sufficient to inhibit bacteria growth, ethylenediaminetetraacetic acid, triethanolamine, glycerol, and urease;
- and
- (b) a diluent solution selected from distilled water and a solution of 2,4-dichlorophenol and distilled water,
- the reagent solution and diluent which when combined contain sufficient N-2-hydroxyethyl-piperazine-N'-2-ethanesulfonic acid and triethanolamine to provide a solution pH of from about 6 to about 8 which is maintainable in the presence of ammonia formed from urea, the N-2-hydroxyethyl-piperazine-N'-2-ethanesulfonic acid, 2,4-dichlorophenol and glycerol cooperating to stabilize urease, both in the reagent solution and when the reagent and diluent solutions are combined.
Dependencies are inferred from the claim text.