Uniformity of Particle Shape for Chromatography Packing Materials used in HPLC.
High Performance Liquid Chromatography (or High-Pressure Liquid Chromatography) is a separation technique used in many areas of analytical chemistry to separate, identify, and qualify various compounds in a specific solution. HPLC utilizes a column that holds chromatographic packing material that retains molecules as they are pumped through the column, the retention time being dependent on the packing material, the carrier liquid (solvent), and the specific type molecule. Each chemical species in the injected sample is most identified by UV and Mass Spec detection. Most traditional analytical HPLC packing materials have an average diameter of approximately 2 to 30 microns and are typically a silica-based or alumina-based material. The particle size of the packing material is usually measured using methods that assume all particles are uniformly spherical. This may not be the case, as in manufacture of the silica and bonding, fines and irregular shaped particles can be a percentage of the final product. As particle size decreases, the effect of fines and irregular shaped particles demands a greater degree of control on incoming quality of the silica material. Variation in particle shape can directly affect reproducible performance.
