Determination of Oil & Grease

Apparatus:

Separating funnel, beaker, measuring cylinder, funnel.

Chemicals: Petroleum Ether 400– 600 C, Conc. HCl, Methyl orange indicator.

Procedure:

* Take 150 ml of sample in separating funnel.

* Add 2-3 ml of concentrated HCl .

* Add 30 ml of Petroleum ether solvent.

* Add indicator methyl orange 2-3 drops.

* Stopper the separating funnel and shake it well.

* Release the gas formed due to reaction of HClwithmetals & organic matter Simultaneously

* Wait for some time till there is distinct separation of two layers (organic & Aqueous phase).

* Remove aqueous layer.

* Give washings with distilled water to remove acid present in excess.

* Test by methyl orange indicator.

* Filter through Ordinary filter paper the organic solvent containing oil &grease Through funnel containing 10 gms Na2SO4 which is previously moistened with Solvent
* Collect the filtrate in a pre-weighed beaker.
* Keep in hot water bath for evaporation of solvent.
* Cool the beaker and weigh.
* Difference between the finally weighed beaker and the empty beaker will
give the amount of Oil & grease.

Calculations: Oil & Grease in ppm = (A-B) x106 /ml. of sample taken
Precision &Bias:
With trichloro-trifluro-ethane as solvent the oil &grease conc. was
12.6 mg/lit Recovery of added oils were 93%with a standard
Deviation of 0.9 mg/lit.

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