Hi everybody,
I am planning to test an extraction process with different solvents (methanol, acetonitrile, water, HCl,...). I wish to test how many cycles it needs in order to finish the extraction. Would you please suggest to me any reference/specification as an example for how to conduct the experiment?
Secondly, another method that I wish to try is dispersive liquid-liquid extraction, based on different literature, I could imagine how the process should be done; however, I got confused in the part of back calculating the sample concentration. Please correct me if I am wrong, I guess the calibrants and samples should be done in the same manner (extraction process) so they will cancel out the dilution factor? How does the enrichment factor contribute to the calculation in this case?
How different they are to compare with other cases such as using SPE, which means only samples will be extracted not the calibrants, and I think in that case we don't cancel out but consider the dilution factor?
Feel free to introduce to me any reference that you think it will help. Thanks in advance.
Best regards.
Ngan
When you say liquid-liquid extraction, I'm assuming that you mean no suspended solids. This also means that the two liquids are immiscible with each other. From the solvents you list, I'm assuming that you are extracting from a non-polar organic solvent (e.g., heptane or benzene). The key parameter you need to get is the apparent equilibrium constant for the solute (Keq). This determines the equilibrium extraction efficiency. The next issue is how long to run the extraction process. Here the degree of agitation of the mixture is critical. I've attached a section of a bioseparations textbook that I'm writing that should provide some guidance. Rather than spending a lot of time on trial and error, I like to use the Hansen solubility parameter approach to define the most optimal solvent choices for the solute of interest. You can find information about Hansen parameters in the CRC Handbook of Solubility and other Cohesive Parameters.
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