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Written by The Clever Chromatographer
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Monday, 07 September 2009 15:01 |
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I had always thought that the biphasic solvent system was fundamental to CCC/CPC separations. However, the “Size-fractionation of silver nanoparticles using ion-pair extraction in a counter-current chromatograph” by Ching-Wei Shen & Tiing Yu. In JCA 1216(2009) 5962 may change my mind. They fractionate silver nanoparticles in suspended in mixture of hexane and toluene. Addition of a phase transfer catalyst, tetraoctylammonium bromide (TOAB), carries the nanoparticles from their aqueous solution into the organic phase. So there really are two phases in the instrument! The separation begins with when a 5 mL aqueous sample of silver nanoparticles is introduced into the 38 mL CCC column running in a tail-to-head direction. Therefore, the aqueous (sample) phase is held in the column while the nanoparticles are extracted from it by TOAB in hexane/toluene. The separation can be manipulated by changing the TOAB concentration. Lower TOAB concentrations tended to spread out the elution more but some of the larger particles did not leave the column if the concentration of TOAB got too low.
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Last Updated on Monday, 07 September 2009 15:07 |
