High-resolution analyses

Authenticity evaluation has recently received increased attention in a number of industries. The complex mixtures involved often require very high resolution analyses and, in the case of determining the authenticity of natural products, very accurate determination of enantiomeric purity. Juchelka et al. have described a method for the authenticity determination of natural products which uses a combination of enantioselective multidimensional gas chromatography with isotope ratio mass spectrometry (28). In isotope ratio mass spectrometry, combustion analysis is combined with mass spectrometry, and the ratio of the analyte is measured versus a... 

Automated, High-Resolution Analyses for the Clinical Laboratory by Liquid Column Chromatography... 

Lin, W. C., Pretlow, T. P., Pretlow, T. G. and Culp, L. A. (1992). High resolution analyses of two different classes of tumor cells in situ tagged with alternative histochemical marker genes. Am. J. Pathol. J4J, 1331-1342. 

AUTOMATED, HIGH-RESOLUTION ANALYSES FOR THE CLINICAL LABORATORY BY LIQUID COLUMN CHROMATOGRAPHY... 

There are at present many investigators involved in the general area of high-resolution analysis for the clinical laboratory. Many recent contributions in this field can be found in the proceedings of the annual symposium series on High-Resolution Analyses and Advanced Analytical Concepts for the Clinical Laboratory (S4, 86, 88). 

J3. Jolley, R. L., and Scott, C. D., Preliminary results from high-resolution analyses of ultraviolet-absorbing and carbohydrate constituents in several pathologic body fluids. Clin. Chem. 16, 687-696 (1970). 

Scott, C. D., and Melville, R. S., co-ch.. Proceedings of the first annual symposium on high-resolution analyses in the clinical laboratory. Amer. J. Clin. Pathol. 53, 677-810 (1970). 

M.J. Greig, B. Bolanos, T. Quenzer, J.M.R. Bylund, FT-ICR-MS using APPI for high-resolution analyses of corticosteroids. Rapid Commun. Mass Spectrom., 17 (2003)2763. 

In addition, the high-resolution analyses of El spectra, as well as metastable spectra, enable one to describe the fragmentations of the low-intensity molecular ion and its fragment ions (Fig. 83). 

Fig. 7) but it is speculated that the first excited 2A1 state lies below the 2BU 2B2 pair of states, which correlate to the A2 n state of CaF. Theoretical work and high-resolution analyses need to be carried out on the monocar-boxylates to verify the ordering of the electronic states. 

PH(i4 n ) fragments have been observed in emission around 342 fun and high resolution analyses of the PH and PD(/4 Hj S ) systems have been... 

In equation (3.1), m is the mass at which two adjacent peaks are resolved by one mass unit (Am = l). Resolved is normally taken to mean overlap at 10% of the height of the peaks. Thus, an analyser with a resolution of 500 can provide unit mass resolution at mass 500 Da. That is, molecules separated by one mass unit can be distinguished. However, that analyser can only distinguish molecules that differ by two mass units at 1000 Da. This illustrates the need for high-resolution analysers to characterize large molecules such as organic phosphates. Furthermore, unit mass resolution is not always sufficient when complex mixtures such as... 

Next, the authors turn to membrane proteins, the major functional constituents of biological membranes. The arrangement of proteins and lipids in membranes is described and the asymmetric, fluid nature of membranes is stressed. The important differentiation between integral and peripheral membrane proteins is discussed as well as the chemical forces that bind them to the membrane. The high-resolution analyses of the structures of selected membrane proteins are discussed, including structure prediction of membrane-spanning proteins. The chapter concludes with a discussion of internal membranes within eukaryotic cells and the mechanisms by which proteins are targeted to specific compartments within cells. 

More recently, some new kinds of modified CDs have been developed which expand the range of compounds which can be resolved and also extend their use in GC. Up to now, the GC columns based on derivatized CDs have realized commercialization. Sigma corporation had developed a series of stable derivatized CD stationary phases named DEX columns for high resolution analyses of optical and positional isomers. They prepared these functional columns by adding permethylated a-CD, /3-CD or y-CD to a phenyl-containing polysiloxane stationary cophase. The DEX columns could separate chiral compounds without derivatization, and enantiomers and positional isomers are resolved by slight... 

A Selection Guide to DEXTM Columns Stable derivatized cyclodextrin stationary phases for high resolution analyses of optical and positional isomers. In Chiral Cyclodextrin Capillary GC Columns. Sigma-Aldrich Co. Available at http // vww.sigmaaldrich.eom/etc/medialib/docs/Supelco/Bulletin/6504.Par.0001.File.tmp/ 6504.pdf. 

High resolution analyses revealed clean grain boundaries both at the interface (Hf,Ta)C/TaSi2 and (Hf,Ta)C/(Hf,Ta)C (Figure 3e). 

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