Merck, 208590-5KG, Molecular sieves, 4 Å

Choosing a Molecular Sieve: 1. The preferential adsorption of one molecule over another depends upon pore diameter and mesh size. 2. The dynamic capacity of the silica gel for adsorbing a particular compound is governed by the internal surface area; the greater the surface area, the greater the dynamic capacity. 3. Rate of adsorption and sharpness of resolution are dependent chiefly on particle size and column packing; a fine particle size gives optimum sharpness of resolution. 4. Liquids are most readily adsorbed from solvents in which they are least soluble; a good solvent makes a good desorbing agent. 5. Highly polar liquids are readily adsorbed. Compounds having hydroxyl groups, or containing oxygen are strongly adsorbed. 6. For similar compounds, the higher the molecular weight the higher the selectivity. 7. For hydrocarbons of similar molecular weight, adsorptivity increases with the number of double bonds.