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Separation type: Bridge Ion Separation Technology, or BIST™ by SIELC Technologies
High Performance Liquid Chromatography (HPLC) Method for Analysis of PEI Large multi-charged molecules such as polyethyleneimine (PEI) can be very difficult to separate and retain on standard columns. PEI is a complex mixture of the molecules of different sizes and geometry with various biological and pharmaceutical applications, such as in tissue cultures, as a transfection reagent, and in carbon dioxide capture. A simple BIST™ method with a step gradient allows for the retention of a single peak for each PEI fraction of varying molecular weight. Using SIELC’s newly introduced BIST™ method, PEI can be retained on a positively-charged anion-exchange BIST™ B column. There are two keys to this retention method: 1) a multi-charged, negative buffer, such as Sulfuric acid (H2SO4), which acts as a bridge, linking the positively-charged PEI molecules to the positively-charged column surface and 2) a mobile phase consisting mostly of organic solvent (such as MeCN) to minimize the formation of a solvation layer around the charged analytes. The step gradient induces some initial BIST™ interactions between PEI and the column surface, and then switches to non-BIST™ mobile phase in order to elute out the molecules. If an isocratic, BIST™ mobile phase were used, the retention times would be too long for practical purposes. Using this new and unique analysis method, PEI fractions can be retained and separated by molecular weight and UV detected at 210 nm.
|Column||BIST™ B+, 4.6×50 mm, 5 µm, 100A|
|Mobile Phase||MeCN Gradient|
|Buffer||H2SO4 – 0.2%, HClO4 – 2%|
|Flow Rate||1.0 ml/min|
|Detection||UV 210 nm|
|Class of Compounds||Polymer, Amine, Aliphatic Amines|