Reference solution

Abstract

A reference solution is provided, which comprises, in a liquid phase, at least one of a first compound and a second compound which are mutually convertible into each other, and at least one catalyst, which catalyzes the conversion between the first compound and the second compound.

1 . A reference solution comprising, in a liquid phase: 
 at least one of a first compound and a second compound which are mutually convertible into each other; and    at least one catalyst, which catalyzes the conversion between said first compound and said second compound.    
     
     
         2 . The reference solution according to  claim 1  wherein the at least one catalyst is an enzyme.  
     
     
         3 . The reference solution according to  claim 2  wherein the enzyme is a hydrolase.  
     
     
         4 . The reference solution according to  claim 1  wherein the first compound is an amide or an ester.  
     
     
         5 . The reference solution according to  claim 1  wherein the first compound is creatinine and the second compound is creatine.  
     
     
         6 . The reference solution according to  claim 5  wherein the at least one catalyst is creatinine amidohydrolase.  
     
     
         7 . The reference solution according to  claim 2  wherein the first compound is carbon dioxide and the enzyme is carbonic anhydrase.  
     
     
         8 . A kit comprising: 
 a container holding the reference solution according to  claim 1 , comprising at least a first compartment and a second separate compartment;    a liquid first phase contained in the first compartment; and    a second phase contained in the second separate compartment, said second phase comprising the at least one of a first compound and a second compound and the at least one catalyst.    
     
     
         9 . The kit according to  claim 8  wherein the container further comprises a third separate compartment, and wherein the at least one of a first compound and a second compound is contained in the second separate compartment and the at least one catalyst is contained in the third separate compartment.  
     
     
         10 . A method of operating the kit according to  claim 8  wherein the second phase is transferred to the first phase by providing fluid communication between the compartments.  
     
     
         11 . A container holding the reference solution according to  claim 1 .  
     
     
         12 . A method of preparing the reference solution according to  claim 1 , comprising the steps of: 
 adding to a liquid phase: 
 the at least one of a first compound and a second compound; and  
 the at least one catalyst; and  
   determining, before or after addition of the at least one catalyst, the equilibrium concentrations of the first compound and the second compound for a selected temperature.    
     
     
         13 . The method according to  claim 12  wherein the step of determining the equilibrium concentrations comprises: 
 measuring the total concentration of the first and second compounds; and    computing the equilibrium concentrations therefrom.    
     
     
         14 . The method according to  claim 12  wherein the step of determining the equilibrium concentrations comprises: 
 measuring the concentrations of each of the first and second compounds; and    computing the equilibrium concentrations therefrom.    
     
     
         15 . The method according to  claim 12  wherein the step of determining the equilibrium concentrations comprises: 
 allowing establishment of the equilibrium concentration of the first and second compounds after addition of the at least one catalyst;    measuring the equilibrium concentration of one of the first and second compounds; and    computing the equilibrium concentration of the other of the first or second compound therefrom.    
     
     
         16 . The method according to  claim 12  wherein the step of determining the equilibrium concentrations comprises: 
 adding to the liquid phase the at least one of the first compound and the second compound in a predetermined amount; and    optionally computing the equilibrium concentrations therefrom.    
     
     
         17 . A method comprising using the reference solution according to  claim 1  for calibration or quality control of a sensor, which is sensitive to at least one of the first and the second compound or a parameter derived therefrom.  
     
     
         18 . The method according to  claim 17  wherein the reference solution, prior to calibration or quality control of the sensor, is conditioned at a conditioning temperature in the temperature range of 18-32° C.  
     
     
         19 . The method according to  claim 18  wherein the temperature range is 20-25° C.  
     
     
         20 . The method according to  claim 17  wherein the reference solution, prior to calibration or quality control of the sensor, is conditioned for a period in the conditioning period range of 0.1-8 hours.  
     
     
         21 . The method according to  claim 20  wherein the conditioning period range is 0.1-3 hours.