Glycerol-salt Mediated Stacking of Nucleic Acids in CZE

Nucleic acid samples with high concentrations of salt could be stacked and well separated during capillary zone electrophoresis (CZE) by adding glycerol into the samples and using a Tris-Borate-EDTA (TBE) buffer (pH 8.3) as the separation medium. The so-called glycerol-salt mediated stacking was found applicable to different types of nucleic acids. Three nucleic acids: a 16s rRNA (1,542 nt), a double stranded DNA (1.6 k bp), and a single stranded DNA (30 nt), were tested as demos in the experiments. When the sample matrix contained 50 mM KCl and 50% (w/v) glycerol, the 16s rRNA sample could be stacked as high as 30 times compared with the sample without KCl. All the nucleic acids could be stacked effectively when high concentrations of glycerol (>50%) and salt (more than 50 mM) were present in the sample matrix, while the dsDNA could be stacked with high concentrations of glycerol (>50%) alone. Cen Qi and Hongping Wei contributed equally to this work.