For studying the M-r distribution and number of species in narrow-range (2 pH-unit wide, in the nominal p/4-6 interval) carrier ampholytes from four commercial sources (Bio-Lyte, Servalyt, Ampholine and Pharmalyte), a 2-D technique was adopted consisting of a focusing step in a liquid phase (Rotofor, yielding 20 fractions) followed by orthogonal CE in both, acidic and basic buffers. As a final step, every other fraction was analyzed by CE-MS. The findings: Ampholine contains 80 different M-r compounds, in the M-r interval 203 to 893 Da, for a total of 325 isoforms. Bio-Lyte consists of 66 different M-r species, in the Mr range 388 to 835 Da, for a total of 436 isoforms. Servalyt is made of 199 different M-r compounds, in the M-r interval 204 to 907 Da, for a total of 1302 isoforms. Pharmalyte pH 4-6.5, comprises 217 amphoteres, in the M-r range 150 to 1179 Da, for a total of 812 isoforms. Pharmalyte appears to be the best brand, with the vast majority of species focusing sharply at their p/position and < 5% "poor" species, distributed along the entire pH gradient, denoting an extremely shallow pH/mobility curve across the p/value.