Use 0.32 ml I.D. columns when higher sample capacity is needed. Use 0.45 mm I.D. columns when only a Megabore direct injector is available and higher column efficiency is desired. Use 0.53 mm I.D. columns when only a Megabore direct injector is available. 0.53 mm I.D. columns have the highest sample capacities at constant df. Column Length Column length influences three parameters of major concern.
Resolution is a square root function of the theoretical plate number.
Figure 16 show the difference in resolution for three different column lengths. Comparison of Resolution and Retention Solute retention is proportional to column length for isothermal temperature conditions. When efficiency is increased by lengthening the column, there is a significant increase in analysis time. Figure 16 shows the difference in retention for three different column lengths. Column head pressure is nearly proportional to column length.