Effect of the nature of the carrier gas on the chromatographic characteristics of monolithic silica capillary columns

Less common applications of monoliths

“…However, the minimum HETP appears to be a function of a product of three variables: pressure required to attain flow velocity giving the minimum at the Van Deemter curve, viscosity of the carrier gas, and diffusion coefficient in the mobile phase. The actual Van Deemter curves support this claim [76]. The effect of the nature of the carrier gas on column efficiency is well know in GLC and heavier carrier gases typically provide for 20 to 30% better efficiency than their lighter counterparts.…”

“…Indeed, Fig. 18 demonstrates a linear correlation between retention time for both sorbates and solubility of helium, hydrogen, nitrous oxide, and carbon dioxide in water [76]. The slope of the straight line is larger for butane than for 2-methylpropane indicating that the former has better access to the active sites at the surface.…”

“…Series of experiments with monolithic silica column using helium, hydrogen, nitrogen, carbon dioxide, and nitrous oxide as the carrier gas and butane and 2-methylpropane as sorbates were performed [76]. Table 2, which summarizes the results, clearly shows that the retention times of the alkanes decrease by a factor of about 2 when switching from helium affording the longest retention times to nitrous oxide in which the retention is the shortest.…”

Applications of monolithic columns in gas chromatography and supercritical fluid chromatography

“…As previously mentioned, stronger influence of the nature of the carrier gas on column efficiency was found in comparison to OT columns. The retention and minimum plate height (H min ) for tested hydrocarbons were observed to decrease in the order of He > H 2 > N 2 > CO 2 ∼N 2 O regardless of a column type (silica, DVB, EDMA) . For the same carrier gas, silica‐based columns have higher productivity than DVB or EDMA based monoliths due to the higher proportion of surface mesopores.…”

“…In previous studies, it was demonstrated that monolithic column properties are particularly sensitive to reaction temperature, polymerization time, and composition of the polymerization mixture . A small change in preparation conditions significantly influenced column efficiency, permeability, and selectivity.…”