Purification methods size-exclusion chromatography

Many chromatographic methods such as permeation chromatography, column chromatography, and size exclusion chromatography have been used to purify CNTs. The size exclusion chromatography (SEC) is the only carbon nanotube purification method in the literature that is not subjected to the acid treatments which tend to create the carboxylic functionality on CNTs. 

The monodispersed nature of dendrimers has been verified extensively by mass spectroscopy, size exclusion chromatography, gel electrophoresis and electron microscopy (TEM). As is always the case, the level of monodispersity is determined by the skill of the synthetic chemist, as well as the isolation/purification methods utilized. 

Two other powerful methods for native RNA purification, one based on size-exclusion chromatography and the other using affinity purification, have been published in the past. The former employs separation of the different species in a transcription reaction (NTPs, small abortive transcripts, the transcribed RNA, and the plasmid DNA) based on size rather than charge (Kim et al., 2007 Lukavsky and Puglisi, 2004 McKenna et al., 2007). 

The purification of all the dendritic intermediates was obtained by SEC (size exclusion chromatography), by simply charging the raw reaction mixtures in DMF or DMA (dimethylacetamide) on a Sephadex LFi-20 column and eluting the dendrimers with 15 mm runs. The intermediates were always obtained with FiPLC purity >90% and could be characterized by various analytical methods such as NMR and FiPLC/MS. 

Once the bacterial cells have been lysed and a crude preparation of plasmid has been obtained, several other methods are available for purification of plasmid from the crude nucleic acid preparation, such as cesium chloride ultracentrifugation, gel filtration/size exclusion chromatography, anion exchange (used in the Qiagen kit mentioned above), and HPLC (Table 2) (see Note 2). 

---