Methods for testing for bioaccumulation

Abstract

Methods comprising: providing a test substance, providing two solvents that are substantially immiscible, introducing a known amount of the test substance and known amounts of the two solvents into a single vessel to create a pre-equilibrium sample, adjusting the concentration of the test substance in the pre-equilibrium sample so that the concentration of the test substance is below the critical micelle concentration of both solvents if the concentration of the test substance is not already below the critical micelle concentration, allowing the test substance to equilibrate between the two solvents over time at a substantially constant temperature, determining the equilibrium concentration of the test substance in each of the solvents, and calculating the partition coefficient.

1. A method comprising:
 providing a test substance;  
 providing two solvents that are substantially immiscible;  
 introducing a known amount of the test substance and known amounts of the two solvents into a single vessel to create a pre-equilibrium sample;  
 adjusting the concentration of the test substance in the pre-equilibrium sample so that the concentration of the test substance is below the critical micelle concentration of both solvents, if the concentration of the test substance is not already below the critical micelle concentration;  
 allowing the test substance to equilibrate between the two solvents over time at a substantially constant temperature;  
 determining the equilibrium concentration of the test substance in each of the solvents; and  
 calculating the partition coefficient.  
 
     
     
       2. The method of  claim 1  wherein the step of allowing the test substance to equilibrate between two solvents over time at constant temperature comprises stirring the pre-equilibrium sample at a rate that sufficiently slow to avoid the creation of an emulsion. 
     
     
       3. The method of  claim 1  wherein the test substance is a surfactant. 
     
     
       4. The method of  claim 1  wherein the solvents are water and n-octanol. 
     
     
       5. The method of  claim 4  wherein the constant temperature is in the range of from about 20° C. to about 22° C. 
     
     
       6. The method of  claim 1  wherein the constant temperature is below the boiling point of the solvents and the test substance. 
     
     
       7. The method of  claim 1  wherein the time required for the test substance to equilibrate between the two solvents extends over several days or weeks. 
     
     
       8. The method of  claim 4  wherein the step of calculating the partition coefficient comprises performing the following calculation: 
         P   ow     =       C     n   ⁢     -     ⁢   octantol         C   water           
 
       wherein C n-octanol  is the equilibrium concentration of test substance in the octanol solvent,
 and C water  is the equilibrium concentration of the test substance in the water solvent.