Capillary electrophoresis in conventional buffers and in 50 microns capillaries permits field strengths as high as 300-500 V/cm with acceptably low thermal zone deformation. However, still higher field strengths (up to at least 2000 V/cm) can be applied without a decrease in resolution if the experiments are performed in the buffers described in this paper. Characteristic of these buffers is their low electrical conductivity and yet satisfactory buffering capacity accomplished either (i) by selecting buffer constituents of relatively high molecular weight and small net charge or (ii) by fractionation of carrier ampholytes (originally introduced for isoelectric focusing experiments) into a series of narrow pH range fractions and using these fractions as buffers, or (iii) by selecting an ampholyte with two acidic groups and one basic group (or one acidic group and two basic groups) and with a pI value close to two of its pK values. In such buffers, aromatic carboxylic acids and proteins used as model substances could be analyzed rapidly. For instance, albumin and transferrin were separated at 30,000 V (1.99 microA) in 15 cm long fused silica capillaries (50 microns ID) within 40 s and the carboxylic acids within 25 s. The resolution was similar to that obtained at standard voltage (5000 V; 0.33 microA), but the analysis time was reduced sixfold. Although not verified experimentally we also suggest the use of relatively high-molecular-weight polyoxyethylene derivatized with one acidic group (for instance, boric acid) and one basic group (an amine), both having the same pK value, which should afford both a very high buffering capacity and very low electrical conductivity (at low buffer concentrations).
The interaction between the anionic polysaccharide sodium
hyaluronate (NaHy) and the positively
charged surfactant tetradecyltrimethylammonium bromide (TTAB) in water
leads to phase separation if
an insufficient amount of salt (NaCl in this study) is added. With
increasing TTAB concentration a
pronounced interaction remains even under single-phase conditions.
This is experimentally supported by
a lowered relative viscosity, a decreased electrophoretic mobility as
determined by high performance
capillary electrophoresis (HPCE) approaching zero mobility at infinite
TTAB concentrations, and changes
in hydrodynamic size as well as an increased relative scattered
intensity as determined by quasi elastic
light scattering (QELS). The extent of this interaction is
controlled mainly by the ionic strength of the
solution and by the concentration of surfactant. The data obtained
are reasonably explained by the model
developed in interaction studies of a positively charged polymer with a
negatively charged surfactant.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.