Extraction funnel manipulation

Some of the more obvious sources of contamination of solvents arise from storage in metal drums and plastic containers, and from contact with grease and screw caps. Many solvents contain water. Others have traces of acidic materials such as hydrochloric acid in chloroform. In both cases this leads to corrosion of the drum and contamination of the solvent by traces of metal ions, especially Fe. Grease, for example on stopcocks of separating funnels and other apparatus, e.g. greased ground joints, is also likely to contaminate solvents during extractions and chemical manipulation. 

The solvent extraction method with which the analytical chemist is most familiar involves placing both liquid phases in a separatory funnel and agitating by hand to effect the partition due to issues of contamination control and limited solution volumes, this implementation is little used in nuclear forensic analysis. Often, phases are mixed in a capped centrifuge cone using a vortex mixer this is particularly convenient in a gloved box, where the loss of manual dexterity impedes the manipulation of a separatory funnel and stopcock. Phase separation is facilitated through the use of a centrifuge. 

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