Common Chromatography Terms A guide for product comparisons! Column Length is proportional to the number of theoretical plates, the degree of separation between solutes, and the retention time. Shorter columns (15-m) exhibit higher resolutions, lower column pressures, and faster analysis times. They're ideal for sample profiling and analysis for up to 45 components. Longer columns (60-m), with more theoretical plates, give better separation between solutes. They are ideal for analyzing complex samples with more than 45 components. Column Internal Diameter (ID) is inversely proportional to column efficiency. Small ID is more efficient, but the large 0.53-mm ID columns are easier to use and do not need specialized instrumentation. Film Thickness is proportional to the column capacity, the solute elution temperature, and the available efficiency of the column. Use thin films (0.1-µm) with 0.25-mm ID columns to separate high-boiling compounds. Use thick films to separate low-boiling compounds.
Phase Definitions Bonded Phase determines the relative retention of the solutes, the number of theoretical plates required for a given separation, and the operating temperature range of the columns. Nonpolar Phases separate a mixture based on boiling point. Polar Phases separate the same mixture based on functional group interaction with the phase material. Match bonded phases to manufacturers' phase codes below. Bonded Phases and their Equivalent Phase Codes | Bonded phase | Equivalent phase codes | | Methyl silicone | DB-1, SE-30, OV-1, OV-101, SPB-1,
BU-1, HU-1, AT-1 | | Methyl 5% phenyl silicone | DB-5, SE-54, OV-23, SPB-5, BU-5,
CPSil-8, Ultra 2, HU-5, Rtx-5 | Carbowax® 20M
(polyethylene glycol) | DB-Wax, Superwax 10, Super-ox,
CP Wax-52, BU-20, HU-20M, Stabilwax | | Cyanopropyl silicone | DB-23, OV-275, SE-2330, SE-2340,
AT-SILAR | Use capillary columns instead of packed columns for shorter analysis times and higher separation efficiencies. Columns are made of fused silica, the purest and most inert form of glass. All columns are tested and are shipped with test results in a stainless steel support cage.
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