Two-dimensional solid-phase extraction

Klejdus B, Vitamvasova D and Kuban V. 2001. Identification of isoflavone conjugates in red clover (Trifolium pratense) by liquid chromatography-mass spectrometry after two-dimensional solid-phase extraction. Anal Chim Acta 450 81-97. 

Dahlin, A. R, Bergstroem, S. K., Andren, R E., Markides, K. E., and Bergquist, J., Poly(dimethylsiloxane)-based microchip for two-dimensional solid-phase extraction-capillary electrophoresis with an integrated electrospray emitter tip. Analytical Chemistry, 77, 5356, 2005. 

Kristjansson, F. Sensitive determination of buspirone in serum by solid-phase extraction and two-dimensional high-performance liquid chromatography. J.Chromatogr., 1991, 566, 250—256... 

Weldegergis, B.T. Crouch, A.M. Gorecki, T. de Villiers, A. (2011) Solid phase extraction in combination with comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry for the detailed investigation of volatiles in South African red wines. Analytica Chimica Acta 701, 98-111... 

Matamoros, V. Jover, E. Bayona, J.M. (2010). Part-per-Trillion Determination of Pharmaceuticals, Pesticides, and Related Organic Contaminants in River Water by Solid-Phase Extraction Followed by Comprehensive Two-Dimensional Gas Chromatography Time-of-Flight Mass Spectrometry. Analytical Chemistry, Vol. 82, No. 2, pp. 699-706, ISSN 0003-2700... 

Keith (1995) presented reference maps of mobilities of modified ribonucleotides and nucleosides separated by two-dimensional TLC on cellulose. Paw and Misztal (1995) isolated cytosine, uracil, and their arabinosides from human plasma by solid-phase extraction and Adsobex minicolumns and separated them by horizontal and ascending TLC in various mobile phases. 

Adahchour, M., Wiewel, J., Verdel, R., Vreuls, R.J.J., Brinkman, U.A.T. (2005) Improved determination of flavour compounds in butter by solid-phase (micro) extraction and comprehensive two-dimensional gas chromatography. J. Chromatogr. A 1086 99-106. 

This problem is circumvented by a construct devised by J. W. Gibbs. Imagine that the gas-phase properties extend unchanged up to the solid surface. Differences between the actual and the unchangedproperties can then be attributed to a mathematical surface, treated as a two-dimensional phase with its own thenuodynamic properties. This provides not only a precisely defined surface phase to accountfor the singularitiesof the interfacial region, but it also extracts them from the three-dimensional gas phase so that it too may be treated precisely. The solid, despite the influence of its force field, is presumed inert and not otherwise to participate in the gas/adsorbate equilibrium. Thus for purposes of thenuodynamic analysis the adsorbate is treated as a two-dimensionalphase, inherently an open system because it is in equilibrium with the gas phase. 

The various microstructural features discussed above are presented in further detail below, and a number of illustrative examples are provided. The following section specifically addresses methods of phase identification with respect to both crystal structure and chemical composition. Finally, the chapter concludes with a brief description of stereology—the quantitative extraction of information about a three-dimensional solid from the two-dimensional images of sections or surfaces that are normally available. 

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