Effect of buffering and buffer replenishment on repeatability in capillary electrophoresis

✍ Scribed by István E. Valkó; Heli Sirén; Marja-Liisa Riekkola; Juho H. Jumppanen

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 547 KB
• Volume: 8
• Category: Article
• ISSN: 1040-7685
• DOI: 10.1002/(sici)1520-667x(1996)8:6<421::aid-mcs7>3.0.co;2-3

✦ Synopsis

Adequate buffering is of vital importance in capillary electrophoresis. Inadequate buffering may result in severe pH drift and erratic separation behavior. The aim of this work was to study the effects of buffering and buffer replenishment on the repeatability of absolute migration times and on the repeatability of electrophoretic mobilities of the analytes determined by the two-marker technique. Three buffers 3-(cyclohexylamino)-l-propane-sulfonic acid (CAPS), 3[(1,1-dimethyl-2-hydroxy-ethyl) amino]-2-hydroxypropane sulfonic acid (AMPSO), and phosphate) with different pK, values were applied at pH 10.6. Both the analytes and the marker compounds were aromatic mono-and dicarboxylic acids. o-Cresol was added to the analyte mixture to act as a pH-sensitive probe. CAPS, which had a pK, value (10.4) closest to the pH of the buffer, was clearly the best buffer at pH 10.6. Buffer replenishment and the use of marker compounds improved the repeatability in every case. From this work it is easy to conclude that when suitable buffer is used and the buffer is replenished after each run, highly repeatable results can be obtained especially when marker techniques are employed. o