Aim: To determine partition coefficient of Naphthalene using shake flask method.
Requirements: Laboratory stand, separatory funnel (500 ml), calibrated cylinder (50 ml, 500 ml), funnel, beaker (500 ml, 100 ml), vial, mini-vial, automatic pipette, distilled water.
Theory: The octanol-water partition coefficient, Kow, describes equilibrium partitioning of a chemical between octanol and water phases. It is an important parameter used in the assessment of environmental fate and transport of organic chemicals because the octanol phase is a surrogate for the lipid phase or organic carbon content of the environmental compartments. Kow is one of the most important physico-chemical characteristics related to sorption on the soil or sediments, and bioaccumulation. Kow is defined as an equilibrium ratio of the concentration in the octanol phase, Co (µg ml-1) and its concentration in the aqueous phase, Cw (µg mL-1), by the equation: Kow = Co/Cw.
Procedure:
- Dissolve 0.011 g of naphthalene in 5 ml of octanol.
- Sonicate the naphthalene solution (5 min).
- Fill the naphthalene solution and 500 ml of distilled water in a separatory funnel.
- Shake the mixture for 10 min.
- Invert slowly and vent (open the stopcock) towards the back of the hood to release the pressure.
- Close the stopcock and shake the funnel gently, then vent again.
- Repeat this step until no more gas is released.
- Separate the octanol and water phases into the beakers.