Extraction principles

Liquid-liquid extraction is used to separate components of a liquid mixture, if separation by distillation is hard to achieve - for example, for liquids with similar boiling points or for temperature-sensitive substances with a high boiling point. Extraction is used to separate a valuable substance as well as to remove unwanted 

Extraction depends upon the difference in solubility of a compound in two immiscible liquids, and is based on the interfacial transfer of a solute. The liquid remaining after treatment with an extracting agent is called raffinate, forming a two-phase system with the extracting agent. 

A distribution ratio is often quoted as a measure of how extractable a species is. The distribution ratio, called Nemst s partition coefficient (Walther Nemst, see box), is equal to the content of a solute i in the first liquid phase 1 (usually the extracting agent) divided by its content in the second liquid phase (phase 2), usually the raffinate  

The distribution ratio may also be related to the masses of solute i and of both liquid phases  

Depending on the system, the distribution ratio is a function of temperature, concentration of the involved species, and other factors such as the unwanted solubility of the extracting agent in the raffinate and vice versa. The properties of an ideal extracting agent are  

---

Thurman, E. M. Mills, M. S. Solid-Phase Extraction Principles an Practice, Wiley NewYork, 1998. 

G. M. Ritcey and A. W. Ashbrook, S olvent Extraction Principles and Applications to Process Metallurgy, Part I, Elsevier, Amsterdam, the Netherlands, 1984. 

M. A. McHugh and V. Kmkonis, Supercritical Fluid Extraction. Principles and Practice, Butterworths, Stoneham, Mass., 1986 T. Suzuki, N. Tsuge, and K. Nagahamaiu Ref. 20 (Area 11). 

M. McHugh and V. Kmkonis, Supercritical Fluid Extraction Principles and Practice, Butterworths, Boston, Mass., 1986. 

E.M. Thurman and M.S. Mills, Solid-phase Extraction Principles and Practice, Chemical Analysis Series Vol. 147, J. Wiley Sons, New York, 1998. ISBN 047161422X. 

M. McHugh and V. Krukonis, "Supercritical Fluid Extraction Principles and Practice", Butterworth, Boston, HA, 1986. 

Extraction principle Hot Conditions Cold Agitation Pressure... 

W. Simpson, Solid Phase Extraction Principles, Strategies and Applications. M. Dekker, New York, NY (1997). 

It is apparent from Chapter 3 that new sample preparation technologies generally are faster, more efficient and cost effective more easily automated and safer use smaller amounts of sample and less organic solvent provide better recovery and meet or exceed precision and accuracy compared to traditional sample preparation techniques. Conventional methods of the analysis of additives in polymers are mostly based on the separation of the polymer matrix and additives by means of extraction. Many extraction principles are... 

Solid Phase Extraction Principles and Practice. By E. M. Thurman Commercial Biosensors Applications to Clinical, Bioprocess and Environmental Samples. Edited by Graham Ramsay... 

McHugh MA, Krukonis VJ (1993) Supercritical fluids extraction Principles and practice. Butterworth-Heineman, Stoneham... 

McHugh, M. A. and Krukonis, V. J., in Supercritical Fluid Extraction Principles and Practice, 2nd. ed., Butterworth-Heinemann, Boston, 1994, 342. 

Ritcey, G. M. Ashbrook, A. W. "Solvent Extraction. Principles and Application to Process Metallurgy. Part II" Elsevier Scientific Publishing Co., New York, 1979. 

The principle of solvent extraction—the distribution of chemical species between two immiscible liquid phases—has been applied to many areas of chemistry. A typical one is liquid partition chromatography, where the principle of solvent extraction provides the most efficient separation process available to organic chemistry today its huge application has become a field (and an industry ) of its own. The design of ion selective electrodes is another application of the solvent extraction principle it also has become an independent field. Both these applications are only briefly touched upon in the chapter of this book on analytical applications (Chapter 14), as we consider them outside the scope of... 

---