Free-Solution Capillary Electrophoresis FSCE

An index of separation speed, N/t, was defined, where N is the number of theoretical plates and t is the migration time [137,340]. The theoretical upper limit of 8500/s for Gln-FITC (H = 0.3 pm) is close to the experimental value of 8300/s. 

FIGURE 6.4 Gas chromatograms of a mixture containing C5-C15 normal alkanes using temperature-programming rates of (a) 10, (b) 20, and (c) 30°C/min. The silicon column was native non-polar, and the carrier gas was air. In all cases, the initial column temperature was 30°C, and the temperature program was initiated at the time of injection [598]. Reprinted with permission from the American Chemical Society. 

The parameters, //(1 IT, //mj, and HiA denote the plate heights due to longitudinal or axial diffusion, injector length, and detector length, respectively. //m usually accounts for about 50% of the total H [547]. These three parameters are given in Equations (6.2), (6.3), and (6.4) as follows [102,340,547,550]  

FIGURE 6.5 Electropherogram of the CE separation of six FITC-labeled amino acids in pH 9.0 buffer. A potential of 2330 V was applied between the injection and detection points, and a potential was applied to the side channels to reduce leakage of the sample. The peaks were 1, Arg 2, FITC hydrolysis product 3, Gin 4, Phe 5, Asn 6, Ser 7, Gly. The inset shows the approximate layout of the device, with a buffer-to-waste distance of 10.6 cm [324], Reprinted with permission from the American Association for the Advancement of Science. 

FIGURE 6.6 Schematic of a serpentine channel on a microchip. The large circle represents the cover slip and the smaller circles represent the reservoirs [136]. Reprinted with permission from the American Chemical Society. 

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Hall et al. (127) compared free solution capillary electrophoresis (FSCE) and micellar elec-trokinetic capillary chromatography (MEKC) techniques with HPLC analysis. Four major food-grade antioxidants, propyl gallate (PG), BHA, BHT, and TBHQ, were separated. Resolution of the 4 antioxidants was not successful with FSCE, but was with MEKC. Separation was completed with excellent resolution and efficiency within 6 min and picomole amounts of the antioxidants were detectable using UV absorption. In contrast, reversed-phase HPLC separation was not as efficient and required larger sample amounts and longer separation time. 

Other methodologies. Desportes et al. (2000) isolated several small wine peptides (Mr <3000) using RP-HPLC on a porous graphite carbon Hypercarb column. The purity of the fractions collected was confirmed by free-solution capillary electrophoresis (FSCE). In a later study, Desportes et al. (2001) determined the peptide sequence of some isolated peptides by Edman degradation. 

CZE, also referred to as free solution capillary electrophoresis (FSCE), or open tubular capillary electrophoresis (OT CE), is the format originally described, in which the capillary is filled with an electrolyte buffer solution. In CZE, molecules are separated directly according to their charge, and inversely according to their solution drag force. Neutral molecules are moved through the capillary by the EOF. There are many additives which can be used to either dynamically deactivate the fused capillary waU, and prevent undesirable solute sticking, or to enhance solute selectivity, or both. 

Free-solution capillary electrophoresis (FSCE) is the major technique used for drug analysis, considering the fact that many drugs have acidic or basic groups that allow them to analyzed as charged molecules. In this technique, the capillary is filled with a buffer solution and the separation is based on the different electrophoretic mobilities of the solutes. Separation of both anionic and cationic solutes is possible, owing to electro-osmotic flow (EOF). The pH of the buffer has a major influence on selectivity, but other factors such as buffer concentration, additives, etc. should also be considered dining method development. ... 

Separation based on size and charge differences between solutes techniques exploiting these differences are termed Capillary Zone Electrophoresis (CZE) or Free Solution Capillary Electrophoresis (FSCE)... 

Free solution capillary electrophoresis (FSCE) is based on the same principles that were described for free electrophoresis in the beginning of this chapter. 

Free Solution-CE, FSCE, also called Capillary Zone Electrophoresis, CZE), molecular size (SDS-CGE in capillaries filled with an acrylamide gel), or isoelectric point (CIEF). 

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