Abstract: A method for calibrating an instrument for the analysis of blood gases which possesses ion-sensitive electrodes and gas-sensitive electrodes and is used for the determination, in a biological fluid, of the concentration of electrolytes and metabolites in solution, and of the pH, pO.sub.2 and pCO.sub.2, the said calibration being carried out with at least one buffered solution containing O.sub.2, a known or tonometer-measured amount of CO.sub.2 and known concentrations of the electrolytes and metabolites to be determined, in which calibration the pO.sub.2 titer is determined beforehand using atmospheric oxygen as reference.

Abstract: An aqueous liquid composition is disclosed. The composition comprises a stabilized glucose oxidase solution having a pH of from about 6.0 to 8.0 and contains phosphate at a concentration of 1500 to 2500 mM/l. The glucose oxidase retains at least 80% of its activity after 10 days at 37.degree. C. The glucose oxidase is preferrably derived from Aspergillus niger, has a concentration of from about 5 to about 50 IU/ml and a pH range of from about 7.1 to about 7.3.

Abstract: This invention relates to a process for stabilizing the enzyme urate oxidase (commonly known as uricase) in liquid form, and to the relative compositions which can then be obtained, with particular reference to compositions containing a Trinder reagent. According to the process of the invention, uricase can be stabilized in liquid form by adding to the composition containing the enzyme a substituted or unsubstituted dicarboxylic acid containing from 2 to 5 carbon atoms, and preferably 4 or 5. Aspartic acid has shown to be particularly effective in providing said stabilizing activity in liquid uricase compositions containing a Trinder reagent.

Abstract: Spontaneous aspecific coloration in so-called Trinder reagents which can alter subsequent colorimetric determinations is inhibited by adding compounds of the chelating agent class to the solution. The resultant compositions contain a peroxidase enzyme, a phenylpyrazone derivative, a compound of phenolic or aromatic amine structure and a stabilizer. Preferred stablizers are ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA).

Abstract: Spontaneous aspecific coloration in so-called Trinder reagents which can alter subsequent colorimetric determinations is inhibited by adding compounds of the chelating agent class to the solution. The resultant compositions contain a peroxidase enzyme, a phenylpyrazone derivative, a compound of phenolic or aromatic amine structure and a stabilizer. Preferred stabilizers are ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA).