A centrifuge is the sure fire way to break the emulsion but not all labs or especially on-site facilities one available.Д§. In this case, the sodium sulfate binds the water leaving the solvent behind so it coalesces into the solvent layer.Д¦. Alternately, you may be able to skip the stirring step and just pour the solvent and emulsion thought the filter paper with the sodium sulfate. Put an 11 cm No.40 Whatman filter paper into a glass funnel and filter to remove sodium sulfate from the solvent. The extract should be nonturbid but may have coloration. Add 1 or more grams of anhydrous sodium sulfate, Na2SO4 and stir with glass stirring rod. Pipette as much solvent/extract as possible into a clean container without taking the water layer. Sigma Aldrich 322431 Potassium Pyrophosphate K4P2O7. Use in the same manner as the table salt. Another very effective salt вЂ“ potassium pyrophosphate. Sodium sulfate can also be sprinkled into the sample as described above or a more aggressive approach for sodium sulfate is described next.Д¤. Hopefully, you will see the salt dropping to the bottom as the droplets from the emulsion coalesce and the emulsion disappears in to cleanly partitioned layers. If you are trying to break an already formed emulsion, you can shake the salt into the sample. If you know that your sample forms emulsions, you can add the salt to the sample prior to shaking with the solvent.

If the emulsion is due to an alkali soap, detergent or surfactant then lower the pH to 2 with sulfuric acid, H2SO4, or hydrochloric acid, HCl, (as recommended in the oil and grease methods, mainly for preservation of the sample) will modify the surfactantвЂ™s charge so that is no longer acts as an emulsifier.ДЈ.

Gently taping the side of the container or stirring the solvent and emulsion layer with a stir bar can help to speed up the separation.Дў. Make sure the sample is covered to reduce any evaporation of the solvent. The easiest is to allow the sample to sit for up to an hour and see if the emulsion decreases.

The following list includes some options that may be useful for reducing the emulsion enough to be able to take a valid measurement.ДЎ. If such an emulsion cannot be broken by any attempted means, the test method may not give representative results for the problem sample.The best way to break or reduce the emulsion depends on the sample matrix. EPA Method 1664, вЂњif the emulsion is greater than one-third the volume of the solvent layer, the laboratory must employ emulsion-breaking techniques to complete the phase separation.вЂќ This is relevant to all oil in water measurements that use liquid-liquid extraction whether the analysis is done by infrared, gravimetric or UV. The boundary between the solvent and the sample will have an emulsion layer that has a cloudy or milky appearance as shown in this photo.ДЄccording to U.S. Certain types of samples, such as those containing detergent, may form emulsions when doing an oil in water extraction into a solvent.

Oil emulsion