Size exclusive capillary electrophoresis separation of DNA oligonucleotides in small size linear polyacrylamide polymer solution

The mobility of analytes in capillary electrophoresis using polymer gels and solutions is usually described as having an inverse relationship with the molecular size (mobility decreases as molecular size increases). The most commonly used models for predicting such mobility are the Ogston model and the Reptation model. However, in this study a new separation phenomenon was observed in which the mobility of DNA oligonucleotides increased with molecular size in a capillary electrophoresis phase (CEP) coated capillary column. The polymer system used was a 11% linear polyacrylamide (Mr = 1500) solution. The log-transformed number of base pairs (log N) of three double stranded oligonucleotides had an inverse linear relationship (r2 > 0.9981) with their migration time in the capillary column. Such a relationship is similar to that observed with size exclusive chromatography.