Cold water extraction

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Cold water extraction (also called CWE for short) is the process whereby a substance is extracted from a mixture via cold water. It is a type of fractional crystallization.

The process generally involves taking a mixture of substances, dissolving them in warm water, and then rapidly cooling the mixture. The insoluble compounds precipitate out of the water, while the soluble ones stay dissolved. The solution can then be separated by filtration or decantation.

This process works by exploiting the differences in solubility of different substances in a low temperature mixture. Opiates are much more soluble in cold water than acetaminophen.[1][2] It is commonly used to separate out opiate-derived drugs that have been mixed with common non-opiate-based analgesics. Cold water extraction is often used with Codeine/Paracetamol, hydrocodone/paracetamol and oxycodone/paracetamol medications.

Items needed[edit]

The cold water extraction process is fairly simple not only due to the simplicity of the method but also because the items needed are minimal and can all be found in a common household. The items used in the process are usually 2 drinking glasses (or any other container), a screen (used to filter) and an item capable of crushing the tablets (mortar and pestle for example). The recommended screen to use is a simple coffee filter due to its high effectiveness when compared to other screens such as a piece of cloth or folded napkin.


Performing a cold water extraction is legal.[3] It is a standard technique in quantitative chemistry and is also part of the educational curriculum. Furthermore, the final product of a cold water extraction is never "pure", always containing traces of the other substances (paracetamol, ibuprofen, aspirin), keeping the drug in its designated schedule. Having a prescription is, as always, required for someone to be in the possession of these prescription only medications, with or without applying a cold water extraction.

See also[edit]


  1. ^ Pubchem. "Diacetylmorphine | C21H23NO5 - PubChem". Retrieved 2016-07-22. 
  2. ^ Pubchem. "acetaminophen | HOC6H4NHCOCH3 - PubChem". Retrieved 2016-07-22. 
  3. ^ "Cold Water Extraction (CWE)". CWEx. Retrieved 2017-02-22.