Concentration-dependent killing action, antibacterial

When preservatives are added to two-phase oil-water systems, depending upon the hydrophilicity of the agent, they partition between the two phases. Bacteria will only grow within the aqueous phase or at the oil-water interface. Thus, preservative lost to the oil is unavailable for antibacterial action. Hence the concentration in the water phase is reduced, affecting the rate of kill, but the capacity of the system is unaffected as... 

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