sep funnelA sep funnel, or separatory funnel, is an essential piece of laboratory glassware for liquid-liquid extractions. And at Macalaster Bicknell Company of New Jersey, we stock four different sizes of sep funnels for a variety of applications.

Separatory Funnel Uses

A sep funnel is most often used to separate out the components of a liquid mixture into two solvent phases of differing densities. Most often, one of the solvent phases will dissolve in water, while the other is a lipophilic organic solvent, meaning it dissolves in fats, oils or lipids. A clear delineation will form between the two liquids, with the denser liquid sinking to the bottom. It can then be drained out through a valve, leaving the lighter liquid within the sep funnel.

To use the funnel, solution is added through an opening at the top. The stopcock is closed during the initial application. The funnel is then sealed and shaken gently by inverting the glassware multiple times. Mixing the solutions should be done carefully, as an emulsion can form if the mixing is too rought. The tap is carefully opened to release vapor pressure, and the sep funnel is set aside to allow for separation. Both the top and bottom taps are opened, allowing the lower phase to be released by gravitation. After the bottom layer has completely drained, the stopcock is closed and the upper layer is poured out into another container.


Sep funnels can take two shapes: a cone, or “pear” shape, or a cylindrical shape. Both funnels have a stopcock situated at the bottom of the funnel. It’s used to release the denser liquid from the funnel.

The sloping sides of the cone-shaped sep funnel are designed to make the identification of layers easier as the liquids separate.


One of the largest risks when using a sep funnel is the build up of vapor pressure. During the inversions, pressure builds up if a gas reaction or physical change occurs. To combat this, simply open the stopper at the top of the sep funnel frequently during mixing. Make sure to point the opening away from your body when opening.

Macalaster Bicknell Company of New Jersey has sep funnels in 125mL, 250mL, 500mL and 1000mL sizes. Contact us today to place your order!