Emulsion stability

DETERMINATION OF EMULSION STABILITY IN EC FORMULATION

Aim:

         To estimate the Emulsion Stability of the given pesticide sample

This method is employed for emulsions which are prepared by adding standard hard water to the pesticide material.

Materials required

         (i) Mohr's type pipette, (ii) Beaker, (iii) 100 ml graduated cylinder, (iv) Dropping funnel and (v) Thermostat.

Procedure

• Take 75 to 80 ml of standard hard water in a beaker and maintain at 30 ± 1oC.

• To this by means of Mohr's type pipette add a quantity of pesticide material which would form a 100 ml of dilute emulsion containing 0.5 per cent (W/V) of the material (in the case of aldrin, gamma BHC, endrin 0.5 per cent; DDT, dieldrin technical 3 per cent; other concentrates 2 per cent). The material should be poured directly into the beaker at the rate of 25-30 ml per minute without touching the sides.

• Stir the contents of the beaker with a glass rod at the rate of 4 revolutions per second during the addition.

• Make up the diluted emulsion to 100 ml with water and transfer immediately to a clean and dry graduated cylinder.

• Keep this at 30 ± 1oC in a thermostat for one hour (in case of methyl parathion, malathion, dimethoate, thiometon, diexinon, diazinon – 30 minutes will be sufficient).

• After the expiry of the time note the volume of the creamed matter at the top or the sediment if any at the bottom or both.