MIGRATION MARKERS FOR CAPILLARY ISOTACHOPHORESIS OF RIBONUCLEOTIDES

2-Chloropropionic, glyoxylic, and levulinic acids were evaluated as mi gration markers for isotachophoresis of ribonucleotides on Ucon-coated capillaries. The effects of leading electrolyte pH and concentration on the elution sequence of ribonucleotides were studied. 2-Chloropropi onic and levulinic acids were effective at pH 4.50 for 10 mM leading e lectrolyte, while glyoxylic and levulinic acids worked best at pH 4.50 for 5 and 1 mM leading electrolytes. These migration markers divided the ribonucleotides into three groups: triphosphate, diphosphate, and monophosphate. At pH values lower than 4.50, mixed-analyte zones were formed. At pH values higher than 4.50, zones mixed with impurities wer e formed. The leading electrolyte concentration affected the effective mobility, elution sequence, concentration effects, and separation spe ed. Low leading electrolyte concentration (ca. 1 mM) provided high sen sitivity and fast separation. The origin of peaklike bands in capillar y isotachophoresis (CITP) is attributed to boundary overlap at the ban d edges. When a dilute sample is analyzed, the band width is mainly de fined by the boundary widths. The boundary width is dependent on the e lectric field strength, temperature, and difference in effective mobil ities of the two separands. High electric field strength, low temperat ure, and large difference in effective mobilities favor narrow boundar ies, resulting in high sensitivity and fast separation. (C) 1998 John Wiley & Sons, Inc.