Electronic Paramagnetic Resonance Spectrometry

A. Wennmalm, B. Lanne, and A.S. Petersson, Detection of endothelial-derived relaxing factor in human plasma in die basal state and following ischemia using electron-paramagnetic resonance spectrometry. Anal. Biochem. 187, 359-363 (1990). 

Various other techniques have been used to determine molybdenum, including adsorption voltammetry [510], electron-paramagnetic resonance spectrometry [512], and neutron activation analysis [513,514]. EPR spectrometry is carried out on the isoamyl alcohol soluble Mo(SCN)s complex and is capable of detecting 0.46 mg/1 molybdenum in seawater. Neutron activation is carried out on the /J-naphlhoin oxime [514] complex and the pyrrolidone dithiocar-bamate and diethyldithiocarbamate complex [513]. The neutron activation analysis method [514] was capable of determining down to 0.32 xg/l of molybdenum in seawater. 

Parman T, Chen G, Wells PG. Free radical intermediates of phenytoin and related teratogens. Prostaglandin H synthase-catalyzed bioactivation, electron paramagnetic resonance spectrometry, and photochemical product analysis. J Biol Chem 1998 273(39) 25079-25088. 

Ohnishi T, Lloyd D, Lindmark DC, Muller M. 1980. Respiration of Tritrichomonas foetus components detected by hydrogenosomes and in intact cells by electron paramagnetic resonance spectrometry. Mol Biochem Parasitol 2 39-50. 

In 1960 Rex (22) first reported the use of electron paramagnetic resonance spectrometry as a method for demonstrating the presence of stable organic free radicals in humic acid. We felt that this technique might provide useful information about the structure of humic acid which was not readily available by other physical methods, particularly if relations between EPR spectra and chemically modified humic acids could be demonstrated. Our preliminary studies (26) confirmed this presumption. 

Electron Paramagnetic Resonance studies Analysis by electron paramagnetic resonance spectrometry (EPR) showed the electrophoresis fraction to contain stable free radicals. A strong EPR signal was obtained at the g factor value of 2.0035-0.0003. The involvement of free radicals in the Maillard reaction has previously been reported (16). Recently also Lessig and Baltes (17) reported the content of extremely stable free radicals in melanoids obtained from the reaction between glucose and 4-chloroaniline. 

Kucherov and Slinkin reported solid-state reactions of H-mordenite and HZSM-5 zeolites with metallic oxides such as CuO (13), Cr2O-, Mo03, and V205 (14-17). The resulting samples were studied by EPR (electron paramagnetic resonance) spectrometry. The authors have shown that the metal cations migrate to cationic sites, where they are coordinately unsaturated. 

SANS, small-angle nuclear scattering EPR, electron paramagnetic resonance spectrometry NMR, nuclear magnetic resonance spectrometry FTIR, Fourier-transform infrared spectrometry SAXS, small-angle X-ray scattering. 

Phenytoin and related xenobiotics can be bioactivated by embryonic prostaglandin H synthase to a teratogenic free radical intermediate. Parman et al. (1998) evaluated the mechanism of free radical formation using photolytic oxidation with sodium persulphate and by electron paramagnetic resonance spectrometry. Incubation of 2 -deoxyguano-sine with phenytoin and prostaglandin H synthase-1 resulted in a 5-fold increase in the oxidation to 8-hydroxy-2 -deoxyguanosine. 

It should be possible to estimate values of Kby determining the concentrations of the radical intermediates in RAFT polymerization by EPR (electron paramagnetic resonance) spectrometry and some effort has been directed to this end. °- Coote and coworkers - have devised methods for calculating absolute values of K by applying ab initio methods. Values of K have also been estimated on the basis of simulation of the polymerization kinetics. Values of K estimated on the basis of the measured concentrations of the radical intermediates are suhstantially lower than those predicted by theoretical calculations. 

P. Dietemann, M. Kahn, S. Zumbuhl, R. Knochenmuss, S. Wiilfert, and R. Zenobi, A Mass Spectrometry and Electron Paramagnetic Resonance Study of Photochemical and Thermal Aging of Triterpenoid Varnishes, Anal. Chem., 73, 2087 2096 (2001). 

Amine-terminated, full-generation PAMAM and PPI dendrimers, as well as carboxylate-terminated half-generation PAMAM dendrimers, can directly bind metal ions to their surfaces via coordination to the amine or acid functionality. A partial hst of metal ions that have been bound to these dendrimers in this way includes Na+, K+, Cs+, Rb+, Fe +, Fe +, Gd +, Cu+, Cu +, Ag+, Mn +, Pd, Zn, Co, Rh+,Ru +,andPt + [18,19,27,36,54,82-96]. Tuxro et al.have also shown that the metal ion complexes, such as tris(2,2 -bipyridine)ruthenium (Rulbpylj), can be attached to PAMAM dendrimer surfaces by electrostatic attraction [97]. A wide variety of other famihes of dendrimers have also been prepared that bind metal ions to their periphery. These have recently been reviewed [3]. Such surface-bound metal ions can be used to probe dendrimer structure using optical spectroscopy, mass spectrometry, and electron paramagnetic resonance (EPR) [86-88,90,97-99]. 

Table 5.2 Summary of selected analytical methods for molecular environmental geochemistry. AAS Atomic absorption spectroscopy AFM Atomic force microscopy (also known as SFM) CT Computerized tomography EDS Energy dispersive spectrometry. EELS Electron energy loss spectroscopy EM Electron microscopy EPR Electron paramagnetic resonance (also known as ESR) ESR Electron spin resonance (also known as EPR) EXAFS Extended X-ray absorption fine structure FUR Fourier transform infrared FIR-TEM Fligh-resolution transmission electron microscopy ICP-AES Inductively-coupled plasma atomic emission spectrometry ICP-MS Inductively-coupled plasma mass spectrometry. Reproduced by permission of American Geophysical Union. O Day PA (1999) Molecular environmental geochemistry. Rev Geophysics 37 249-274. Copyright 1999 American Geophysical Union...

Electron paramagnetic resonance spectroscopy (EPR) (also called electron spin resonance spectroscopy, ESR) has been scarcely applied in the field of art and art conservation. Some work can be found in which EPR is used as complementary technique to SEM-EDX, NMR, and mass spectrometry (MS) for studying free radicals occurring in polymerization, pyrolytic, oxidative, and other radical degradative processes in artwork, as well as in the characterization of varnishes and oleoresinous media [42]. 

Dietemann P, Kahn M, Zumbiihl S, Knochenmuss R, Wiilfert S, Zenobi R (2001) A mass spectrometry and electron paramagnetic resonance study of photochemical and thermal aging of triterpenoid varnishes. Anal Chem 73 2087-2096. 

Tn 1963 we began to investigate lignin preparations by electron paramagnetic resonance (EPR) spectrometry. This technique can detect paramagnetic species, particularly organic free radicals. The types of information available from EPR measurements can be summarized as follows ... 

Direct methods for determining the combinational form of an element or its oxidation state include infrared absorption spectrometry, X-ray diffraction and, more recently, electron paramagnetic resonance - nuclear magnetic resonance -and Mossbauer spectrometry. With such techniques the combinational forms of major elements in soil components such as clay minerals, iron, manganese and aluminium oxyhydroxides and humic materials and the chemical structures of these soil components have been elucidated over the past 50 years. These direct, mainly non-destructive, methods for speciation are dealt with in some detail in Chapter 3 and are not further discussed here. 

These sites can be studied by electron paramagnetic resonance (EPR), ultraviolet (UV) spectrometry, x-ray photoelectron spectroscopy (XPS), and other methods. Besides, a quantitative study of redox sites can be carried out with the help of a volumetric or gravimetric study of the adsorption of the oxidizing or the reducing molecules. 

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