A Convenient Method For Supernatant Removal The removal of unwanted supern&.nts fram centrifuged samples can be greatly facilitated by using the apparatus shown here. A standard 250-ml side arm filter flask is fitted with a single hole stopper. 4 glass tuhe nearly long enough to reach the bottom of the flask is fitted in the stopper. A suitable length ('lz-l m ) of Tygon tubing is connected to the glass tnhing. The free end of the Tygon tubing is connected to a. Pasteur pipet, The flask is now inverted and clamped securely to laboratory hardware, ideally a goose-neck faucet. The side arm is connected to a water aspirator with thick wall vacuum tubing. I n practice, tho Pasteur pipet is used to remove the supernatant from the sample. The supernatant is drawn into the flask and carried directly into the water stream via the aspirator. T o clean the flask, place the Pasteur pipet in soapy water for a iew seconds with the aspiration rate as high as possible. The pi& is quickly lifted fram the water and momentum of the water will cause the soap solution to strike the top of the flask and flow down t,hesides. The process is repeated with distilled water to rinse the flask.
804
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Journal of Chemical Education
