No abstract

Quantitative analysis in capillary electrophoresis based on time-scale electropherograms generally uses time-corrected peak areas to account for the differences in apparent velocities between solutes. However, it could be convenient and much more relevant to change the time-scale electropherograms into mass relative distribution of the effective mobility or any other characteristic parameter (molar mass, chemical composition, charge density, ...). In this study, the theoretical background required to perform the variable change on the electropherogram was developed with an emphasis on the fact that both x and y axes should be changed when the time scale electropherograms are modified to get the distributions. Applications to the characterization of polymers and copolymers by different modes of capillary electrophoresis (CE) are presented, including the molar mass distribution of poly-L-lysine oligomers by capillary gel electrophoresis (CGE), molar mass distribution of end-charged poly-l-alanine by free solution CE, molar mass distribution of evenly charged polyelectrolytes by CGE, and charge density distribution of variously charged polyelectrolytes by free solution CE.

The aggregation mechanisms of amyloid β peptides depend on multiple intrinsic and extrinsic physico-chemical factors (e.g. peptide chain length, truncations, peptide concentration, pH, ionic strength, temperature, metal concentrations…). Due to this high number of parameters, the formation of the oligomers and their propensity to aggregate make the elucidation of this physiopathological mechanism a challenging task. From the analytical point of view, up to our knowledge, few techniques are able to quantify, in real time, the proportion and the size of the different soluble species during the aggregation process. This work aims at demonstrating the interest of modern Taylor dispersion analysis (TDA) performed in capillaries (50 µm i.d.) to unravel the speciation of β-amyloid peptides in low volume peptide samples (~100 µL) with an analysis time of ~ 3 min per run. TDA was applied to study the aggregation process of and Aβ(1-42) peptides at physiological pH and temperature, where more than 140 data points were generated with a total volume of ~1 µL over the whole aggregation study (about 0.5 µg of peptide). TDA was able the give a complete and quantitative picture of the Aβ speciation during the aggregation process, including the sizing of the oligomers and protofibrils, the consumption of the monomer, and the quantification of different early and late-formed aggregated species.