Stationary phases strong cation exchange

The application of polymer monoliths in 2D separations, however, is very attractive in that polymer-based packing materials can provide a high performance, chemically stable stationary phase, and better recovery of biological molecules, namely proteins and peptides, even in comparison with C18 phases on silica particles with wide mesopores (Tanaka et al., 1990). Microchip fabrication for 2D HPLC has been disclosed in a recent patent, based on polymer monoliths (Corso et al., 2003). This separation system consists of stacked separation blocks, namely, the first block for ion exchange (strong cation exchange) and the second block for reversed-phase separation. This layered separation chip device also contains an electrospray interface microfabricated on chip (a polymer monolith/... 

R Pecina, G Bonn, E Burtscher, O Bobleter. High-performance liquid chromatographic elution behavior of alcohols, aldehydes, ketones, organic acids and carbohydrates on a strong cation-exchange stationary phase. J Chromatogr 287 245-258, 1984. 

Different developed analytical method are discussed in this chapter related to the determination of illicit substances in blood (either whole blood, plasma, or serum), OF, urine, and hair. These methods take into consideration the particular chemical and physical composition of the matrix and applies each time a suitable pretreatment to remove interfering and matrix effect, to maximize recoveries and to achieve a suitable enrichment if necessary. For liquid matrices the applications of the most common techniques are considered from simple PPT to SPE and LLE the results of recent works from literature are reported and new trends as online SPE, pSPE, automated LLE (SLE) or MAE are examined. Several stationary phases have been shown to be suitable for determination of illicit drugs Cl8, pentafluorophenyl, strong cation-exchange, and HILIC columns. The trend toward fast chromatography is investigated, both UHPLC and HPLC with appropriate arrangements moreover, results obtained with different ion sources, ESI, A PCI, and APPI are compared. 

The separation of TCAs and related quaternary ammonium compounds on different strong cation exchangers was studied by Enlund et al. [128], Four cation-exchange materials, possessing propanesulfonic acid ligands, were prepared from different 5-pm bare-silica particles ranging from 80 to 800 A in pore size. The best separation was produced on the small-pore materials, but the efficiency and symmetry were similar on all stationary phases compared. 

In recent years, a small number of new phases have become available that are more suited to CEC. Phase Separations (Deeside. UK) have produced a SCX stationary phase. This is a strong cation-exchange material which contains aminopropyl-derivatised silica that has sulphonic acid groups covalently attached to the amino end of a short alkyl chain. The sulphonic acid groups are effectively ionised at all working pHs due to their low p/faS. Fig. 4.5 shows the dependence of EOF on pH of the mobile phase for a capillary packed with Phase Separations SCX stationary phase. The EOF is almost the same over the whole range. It increases beyond pH 7, presumably due to the added ionisation of the surface silanols. 

Fig. 18.16 Separation of proteins on a mixed stationary phase. (Reproduced by permission of Elsevier Science Publishers BV from Z. el Rassi and C. Horvath, J. Chromatogr., 359, 255 (1986). Stationary phases (A) strong anion exchanger (Zorbax SAX-300) (B) strong cation exchanger (Zorbax SCX-300) (C) 1 1 mixture of A and B. Particle size, 7pm. Column, 8cm x 6.2 mm i.d. (A and B), 10cm X 4.6mm i.d. (C) mobile phase, 20mM tris-HCI (pH 7.0), gradient from 0 to 0.3 M sodium chloride in 40 min, 1.5 ml min (A and B), 1 ml min (C) UV detector, 280 nm. RNase = ribonuclease A CYT = cytochrome c CHY = a-chymotrypsinogen A LYS = lysozyme Hb = haemoglobin CON = conalbumin LAC A = j5-lactoglobulin A.

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