Micra NPS TAS (C30)
Micra NPS phases are based on non porous silica. In contrast to conventional porous silica non porous silica has a smaller surface area. Non porous means that the mass transfer of those packings is accelerated. This fact results in higher efficiencies of the corresponding HPLC columns. Due to lower surface area compounds show lower retention on non porous packings compared to porous ones. To achieve the same retention in the chromatography of small molecules about 20% less organic has to be used with RP packings. Therefore the use of non porous packings is in those areas where high organic mobile phases are required. Columns packed with non porous stationary phases are the columns of choice for the chromatography of macromolecules like proteins, polynucleotides and polymers. On porous packings those molecules have to move by diffusion inside the pores. Due to the diffusion coefficient of macromolecules is much lower compared to small molecules the efficiencies of columns packed with porous particles is much lower compared to those that can be achieved on columns packed with non porous stationary phases. There are several bonding types available: two non endcaped C18 bondings called ODS 1 and ODS 2, an endcaped C18 packing ODS 3E and a C30 packing called TAS.