Two-dimensional liquid chromatograph

Two-dimensional liquid-chromatographic separations are also of great potential interest in polymer analysis. After separating macromolecules, according to only one type of heterogeneity, by one experiment, there is no chance to get a correlation between different... 

Isobe, T., Uchida, K., Taoka, M., Shinkai, F., Manabe, T., Okuyama, T. (1991). Automated two-dimensional liquid chromatographic system for mapping proteins in highly complex mixtures. J. Chromatogr. 588, 115-123. 

Venkatramani, C.J., Zelechonok, Y. (2003). An automated orthogonal two-dimensional liquid chromatograph. Anal. Chem. 75, 3484-3494. 

B. Zhang, S. Mathewson, and H. Chen, Two-dimensional liquid chromatographic methods to examine phenylboronate interactions wifli recombinant antibodies, J. Chromatogr., A1216 (2009) 5676-5686. 

Berek D. Strategies in two-dimensional liquid chromatographic separation of complex polymer systems. Macromol Symp 2001 174 413-34. 

Two-Dimensional Liquid Chromatographic Analysis of Amino Acid Enantiomers... 

Two-dimensional liquid-chromatographic separations can be performed in the hnear ( heart-cut ) format or in the comprehensive mode. In the former case, one (or a few) fractions are isolated from the sample and these are subsequently subjected to a second separation. An advantage of this approach is that the specific fraction(s) can be subjected to two (lengthy) high-resolution separations. A great disadvantage is that only one or a few small fractions of the sample are extensively characterized. In comprehensive two-dimensional LC the entire sample is subjected to two different separations. The word comprehensive is justified if the final (two-dimensional) chromatogram is representative of the entire sample (Schoenmakers et al, 2003). The recommended notation for linear ( heart-cut ) two-dimensional LC is LC-LC, whereas comprehensive two-dimensional LC is commonly denoted by LCxLC (Schoenmakers etaL, 2003). 

D. Berek, Two-dimensional liquid chromatography of synthetic macromolecules, in Handbook of Size Exclusion Chromatography and Related Techniques, vol. 91 (Chromatographic Sciences Series), C.-s. Wu, ed., Marcel Dekker, Inc., New York, 2004, p. SOT, Anal. Bioanal. Chem. 396, 421, 2010. 

Table 1 Compatibility table Possible couplings of selected two-dimensional column chromatographic systems based upon dimension compatibility. Note that the coupling order is important. Entries do not imply that the method has been implemented in practice. The coupling may be online direct coupling (e.g., GC-GC) or may involve special interfaces that allow phase isolation in the coupled method (e.g., vaporization of liquid phase in discrete sampling injection in NP-LC-GC)...

Coupling of different chromatographic separation methods enables one to resolve multiple distinctive components. Two-dimensional liquid chromatography (2D-LC) has been shown to be an extremely useful tool for the investigation of the molecular heterogeneity of complex polymers [173-176], Until recently the application of 2D-LC was limited to ambient temperature and it was only in 2010 that the introduction of high-temperature 2D-LC was announced. 

There is growing interest related to rapid screening and full characterization of the constituents of plants with medicinal properties. The high content in polyphenols accounts for in vitro and in vivo antioxidant activity of the extracts obtained from plants on the other hand, the high complexity of the samples extracted, depending on the method employed, may preclude complete resolution by conventional HPLC techniques. For this purpose, a comprehensive two-dimensional liquid chromatography (LCxLC) system, comprised of an RP-Amide first dimension and a partially porous octadecylsilica column in the second dimension, has been compared with a one-dimensional system (125). The chromatographic methods optimized in this research allowed the complete resolution and full characterization of polyphenols and xanthines in mate extracts. 

A. Dossena, G. Galaverna, R. Coiradini and R. Marchelli, Two-dimensional liigh performance liquid chromatographic system foi the determination of enantiomeric excess in complex amino acid mixtures. Single amino acids analysis , ]. Chromatogr. 653 229-234 (1993). 

F. Enri and R. W. Erei, Two dimensional column liquid chromatographic technique for resolution of complex mixtures , ]. Chromatogr. 149 561-569 (1978). 

Pasch, H., Brinkmann, C., Much, H., Just, U. (1992). Chromatographic investigations of macromolecules in the critical range of liquid chromatography. II. Two-dimensional... 

Two-dimensional TLC uses the same liquid chromatographic procedure twice to separate spots that are unresolved by only one process. After a sample is run in one solvent, the TLC plate is removed, dried, rotated 90 degrees, and run in another solvent. Any of the spots from the first run that contain mixtures can now be separated. The finished chromatogram is a two-dimensional array of spots. 

Tentative confirmation of suspected liquid chromatographic peaks has been achieved in the analysis of carazolol and seven sedatives in swine kidney, by using photodiode-array detection in the wavelengUi range of 220-320 nm. It was reported (526) that further identification could be made possible if the corresponding fractions of the eluate were submitted off-line to two-dimensional thin-layer chromatography. 

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