Glycerol-enhanced separation of DNA fragments in entangled solution capillary electrophoresis

(Hydroxyalkyl)methylcellulose additives to borate buffers have been used to create physically entangled solutions for fractionation of biological molecules by high-performance capillary electrophoresis, i.e., ESCE. We have observed that addition of glycerol to an entangled solution containing (hydroxypropyl)methylcellulose (HPMC) in Tris-borate buffer markedly improved the separation of double-strand DNA molecules ranging from less than 100 bp to about 1 kb by ESCE. This range of DNA fragment sizes is well suited to many PCR-based studies. We attribute the improved ESCE performance to the borate present in the buffer system. Borate can form dimeric 1:2 borate:didiol complexes with both glycerol and HPMC, acting as a central linkage to allow an entangled solution with different pore size to form chemically.