Abstract
As a last part of an investigation on all 2‐pH‐unit intervals of carrier ampholytes (CAs) for IEF (see Electrophoresis 2006, 27, 3919–3934; 2006, 27, 4849–4858; 2007, 28, 715–723) two different lots of Servalyt CAs, in the pH 9–11 range, have been analyzed by a 2‐D technique based on preparative Rotofor fractionation followed by capillary electrophoresis mass‐spectrometry of 10 out of 20 fractions harvested, in the second dimension. The findings: the two lots contain 65 and 69 different M~r~ compounds, in the M~r~ interval of 232–667 Da, for a total of 341–387 isoforms, respectively. Since this is a chaotic organic synthesis, the high reproducibility (here demonstrated for the first time during the 40 years of existence of CAs) of the synthetic process (for two batches produced at 6 years of distance) is remarkable, considering that a 94% agreement for the individual chemicals and 88% agreement for the total number of isoforms for the two lots is found. It is additionally demonstrated that the lower p__I__ species are accompanied by considerably more isoforms than the high p__I__ forms and that in all cases such isoforms consist of family of compounds clustered around the p__I__ of the parental form, with a p__I__ spread of ca. 0.1–0.2 pH units.