Preventive MaintenanceConditioning columns157back of nut). Adjust the septum purge flow rate to no more than6 ml/min.c. Cap inlet fittings into detector(s) to prevent entry of air and/orcontaminants.3. Establish a stable flow of carrier gas through the column. He ispreferred; however, N1 is adequate for conditioning packed columns.Do not use H1 because it vents into the column oven duringconditioning.a. For 1/8•and 1/4•inchcolumns (with 2 mm id), a flow rate of about30 ml/min is sufficient; for 1/4•inchcolumns (with 4 mm id), a flowrate of about 50 ml/min is adequate.b. For a rigid glass capillary column (with 0.25 mm id), establish ahead pressure (in psi) equal to about half the column length (inmeters). For example, a 50 m column should have a head pressureof about 25 psi (172 kPa).c. For a fused silica capillary column, establish a column headpressure (in psi) equal to column length (in meters).4. Set oven temperature to 100^C for about an hour. Then slowly raiseoven temperature to the conditioning temperature for the column(never greater than the maximum temperature limit for the column;30^C less than the maximum is usually sufficient).Caution Overheating may shorten column lifetime.Conditioning may continue overnight for packed columns and can bemuch less for capillary columns.5. If the conditioned column is not to be used immediately, remove itfrom the oven and cap its ends to prevent entry of air, moisture,and/or contaminants.
