Knowledge About Normal Phase Solid Phase Extraction
In the lab, we often use SPE cartridges, but do we understand the principle of normal phase solid phase extraction?
Normal phase solid phase extraction is the dissolution of polar substances in non-polar solvents (diethyl ether, n-butane, etc.), which are adsorbed by a strong polar stationary phase. The interaction between them includes dipole pairs, hydrogen bonds, and electron pairs. This material needs to be eluted with a strong polar substance, and the solvent strength factor ε>0.6 of the eluent is required, such as methanol (ε=0.73). The commonly used adsorbents are alumina, magnesium silicate, diatomaceous earth, and silica gel.
Normal phase solid phase extraction has been used to separate and purify vitamin D and its metabolites, fatty acids, carbohydrates and phenolics in biological samples. Generally used as a strong polar adsorbent such as diatomaceous earth, silica gel, alumina, magnesium silicate, etc., the target analyte is a non-polar or weakly polar compound, such as fat-soluble vitamins, pesticides and the like. The filler is most widely used in silica gel.
A large amount of silanol-based polar sites present on the surface of silica gel can adsorb moderately polar compounds such as alcohols, aldehydes and organic halides dissolved in non-polar solvents, and then washed with a solvent larger than 0.6. Take off. In recent years, molecular sieves, glass beads, graphite carbon, and chemically bonded phases with amino groups and cyano groups, which are slightly weaker than silica gel, have been used as fillers.
The latter applies to the separation of moderately polar compounds such as aldehydes, ketones, and nitro compounds. Hawach’s normal phase solid phase extraction columns include Normal Phase Alumina SPE Cartridges, Normal Phase CN SPE Cartridges, Normal Phase Diol SPE Cartridges, Normal Phase PR Grade Florisil SPE Cartridges, Normal Phase Silica SPE Cartridges.