Capillary electrophoresis compositional analysis

Staggemeier, B., Huang, Q.R., Dubin, P.L, Morishima, Y., and Sato, T., Determination of the compositional distribution of copolymers by frontal analysis continuous capillary electrophoresis, Anal. Chem. 72, 255, 2000. 

The average DS as determined by these methods provides only the simplest characterization of these derivatives, and further analysis was necessary to characterize the mixture of SBE bands of different levels of substitution. Due to the presence of the anionic sulfonate substituent, it is possible to use capillary electrophoresis (23), to separate the SBE-CD substitution bands and to characterize the fingerprint of the composition (Fig. 10). Anion exchange chromatography (24) was utilized to isolate separate substitution bands (mono- to deca-derivatives) that were subsequently identified by NMR and fast atom bombardment mass spectroscopy (FAB-MS). 

The use of mass spectrometry (MS) as a detection system is inevitable in the evolution of any separation method, especially CE where the liquid flow rate ( 1 ml/min) is compatible with conventional mass spectrometers. The combination of a high-efficiency liquid-phase separation technique, such as capillary electrophoresis, with MS detection provides a powerful system for the analysis of complex mixtures. Analyte sensitivity and the mass spectrum obtained depend on the electrospray ionization (ESI) voltage, ion-focusing parameters, and buffer composition. In general, the greatest sensitivity is obtained by employing conditions that facilitate desolvation and minimize cluster formation.47 Three ways of interfacing for CE-MS... 

The first volume concentrates on separation techniques. H. Pasch summarizes the recent successes of multi-dimensional chromatography in the characterization of copolymers. Both, chain length distribution and the compositional heterogeneity of copolymers are accessible. Capillary electrophoresis is widely and successfully utilized for the characterization of biopolymers, particular of DNA. It is only recently that the technique has been applied to the characterization of water soluble synthetic macromolecules. This contribution of Grosche and Engelhardt focuses on the analysis of polyelectrolytes by capillary electophore-sis. The last contribution of the first volume by Coelfen and Antonietti summarizes the achievements and pitfalls of field flow fractionation techniques. The major drawbacks in the instrumentation have been overcome in recentyears and the triple F techniques are currently advancing to a powerful competitor to size exclusion chromatography. 

The capacity of the nanoparticles to adsorb proteins and to activate the complement in vivo after intravenous administration will influence the fate of the carrier and its body distribution. To approach this aspect, in vitro tests have been developed to investigate the profile of the type of serum proteins that adsorbed onto the nanoparticle surface after incubation in serum and to evaluate the capacity of the nanoparticles to induce complement activation. The analysis of the protein adsorbed onto the nanoparticle surface can be performed by 2D-polyacrylamide gel electrophoresis. This technique allows the identification of the proteins that adsorbed onto the nanoparticle surface. To evaluate modifications of the composition of the adsorbed protein with time, a faster method based on capillary electrophoresis can also be used. Finally, the activation of the complement produced by nanoparticles can be evaluated either by a global technique or by a specific method measuring the specific activation... 

Capillary electrophoresis (CE) is an emerging analytical technique for determination of catechins. The majority of CE studies involve the analysis of catechins in tea infusion, extracts as well as supplements. The three variants of CE suitable for the analysis of catechins include capillary zone electrophoresis (CZE), micellar electro-kinetic chromatography (MEKC), and microemulsion electrokinetic chromatography (MEEKC) with UV detection. In general, the resolution of MEKC was found to be superior to CZE for separation of catechins. MEEKC is a relatively new technique, and the few reports available suggest that it offers a performance similar to MEKC. CE conditions are often quite complex, and many factors, such as buffer composition, pH, presence of surfactants, and column temperature, can all affect the quality of separation and should be optimized individually. On the other hand, CE offers several advantages over HPLC. The short analysis time (<20 minutes), low running costs, and reduced use of solvents make it an attractive alternative for routine analysis of catechins. 

The 13 molecnles present in sweet white wines were formally identified (Bian, 1996) by fractionation and analysis of the molecules using HPLC (Voyatzis, 1984 Kovac et al, 1990) and then capillary electrophoresis (Bian et al., 1995), HPLC and NMR. It is thns possible to define the phenolic composition of varions white wines, althongh concentrations are still somewhat approximate (Table 6.18). 

Shihabi, Z.K. Effect of sample composition on electrophoretic migration application to hemoglobin analysis by capillary electrophoresis and agarose electrophoresis. J. Chromatogr. A, 1027, 179, 2004. 

Tremendous advances have been made in the past few decades in both the range and sensitivity of the analytical methods now available. For the purpose of solubility measurement, solution compositions can be measured by any eonvenient analytical technique, among which may be listed liquid chromatography (HPLQ, spectroscopy (UV, IR, NMR and mass), differential scanning calorimetry (DSC), differential thermal analysis (DTA), thermogravimetric analysis (TGA), refractometry, polarimetry, and most recently capillary electrophoresis (Altria, 2000). 

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