HP 5890 Series II, Справочное руководство

Страница: 157 / 244

Preventive Maintenance
Conditioning columns
157
back of nut). Adjust the septum purge flow rate to no more than
6 ml/min.
c. Cap inlet fittings into detector(s) to prevent entry of air and/or
contaminants.
3. Establish a stable flow of carrier gas through the column. He is
preferred; however, N
1
is adequate for conditioning packed columns.
Do not use H
1
because it vents into the column oven during
conditioning.
a. For 1/8•and 1/4•inchcolumns (with 2 mm id), a flow rate of about
30 ml/min is sufficient; for 1/4•inchcolumns (with 4 mm id), a flow
rate of about 50 ml/min is adequate.
b. For a rigid glass capillary column (with 0.25 mm id), establish a
head pressure (in psi) equal to about half the column length (in
meters). For example, a 50 m column should have a head pressure
of about 25 psi (172 kPa).
c. For a fused silica capillary column, establish a column head
pressure (in psi) equal to column length (in meters).
4. Set oven temperature to 100
^
C for about an hour. Then slowly raise
oven 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 be
much less for capillary columns.
5. If the conditioned column is not to be used immediately, remove it
from the oven and cap its ends to prevent entry of air, moisture,
and/or contaminants.