Electrophoretic nuclear magnetic resonance

A novel application of NMR spectroscopy is electrophoretic NMR (ENMR), where a POSE diffusion experiment is undertaken on a sample in an electrochemical cell in which electric current is flowing, i.e. there is also an electric field present. The NMR pulse sequence illustrating this method is depicted in Fig. 7.17. The resulting echo decay follows a relationship given by 

77 Pulse sequence for ENMR experiment (FID = free induction 

This technique has been used to determine transference numbers in gel electrolytes in a manner generally considered more reliable and less ambiguous than electrochemical methods, yielding net transference numbers regardless of the extent of ion association and is thus well suited for salt concentration studies as shown by Dai and Zawodzinski.  

Many research groups within the polymer electrolyte field have benefited from the great power and vast number of possible applications of the NMR technique. As a stand-alone method which yields both structural and dynamical information at the ionic and molecular level, or more commonly when used in conjunction with electrical and thermal characteriza-the contribution of NMR spectroscopy to this field is firmly established and will provide continued understanding as new polymer electrolytes are developed. 

DEROME, Modem NMR Techniques for Chemistry Research, Pergamon Press, Oxford, 1993 

---

Johnson, CS He, Q, Electrophoretic Nuclear Magnetic Resonance, Advances in Magnetic Resonance 13, 131, 1989. 

Pulsed Field Gradient and Electrophoretic Nuclear Magnetic Resonance... 

Cabovska, B., Kreishman, G. R, Wassell, D. F., and Stalcup, A. M., Capillary electrophoretic and nuclear magnetic resonance studies of interactions between halophenols and ionic liquid or tetraalkylammonium cations,. Chromatogr. A, 1007,179-187, 2003. 

Nowadays, the chromatographic, electrophoretic, spectroscopic, biosensor, and membrane methods are the ones most commonly applied (Fig. 3) [19-23,42,43], Among the spectroscopic methods, investigators use optical rotation measurements, nuclear magnetic resonance (NMR) spectroscopy, and infrared (IR) spectroscopy. The latter, as differential scanning calorimetry (DSC), can... 

R445 G. Malandrinos, K. Dodi, M. Louloudi and N. Hadjiliadis, On the Mechanism of Action of Thiamin Enzymes in the Presence of Bivalent Metal Ions , J. Inorg. Biochem., 2000, 79, 21 R446 A. K. Malik and W. Faubel, A Review of Capillary Electrophoretic Separations and their Studies by Nuclear Magnetic Resonance , J. Capillary Electrophor. Microchip TechnoL, 1999, 6, 97... 

C. S. Johnson. 1996. Electrophoretic NMR. In D.M. Grant, R.K. Harris, editors. Encyclopedia of nuclear magnetic resonance. Chichester Wiley p 1886-1895. 

The derivatization of analytes is very important in several branches of analytical chemistry. It expands the fields of application of various spectroscopic techniques (ultraviolet-visible (UV-vis), fluorimetry, nuclear magnetic resonance (NMR), and mass spectroscopies), and in several cases increases also the selectivity and sensitivity of these techniques. Derivatization is also an inevitable tool in all chromatographic and electrophoretic techniques. In gas chromatography (GC), the main importance of derivatization is the improvement of the volatility/thermal stability of the analytes, and in all of the discussed separation techniques it has the potential of increasing the selectivity of the separation (including enantiomeric separations) and the sensitivity of the detection. 

This review presents recent developments in the application of nuclear magnetic resonance (NMR) spectroscopy to study ionic liquids. In addition to routine structural characterization of synthesized ionic liquids, availability of multitude of advanced NMR techniques enables researchers to probe the structure and dynamics of these materials. Also most of the ionic liquids contain a host of NMR-active nuclei that are perfectly suitable for multinuclear NMR experiments. This review focuses on the application of NMR techniques, such as pulsed field gradient, relaxometry, nuclear Overhauser effect, electrophoretic NMR, and other novel experiments designed to investigate pure ionic liquids and the interaction of ionic liquids with various salts and solutes. 

---