PerkinElmer TORION T-9, Руководство пользователя

Страница: 272 / 276

268 . Torion T-9 User’s Guide
Observation Example Possible cause
Tailing (1) A surface to which the sample is
exposed is adsorptive. This can arise
because the injector, column or transfer
lines are not deactivated well enough, or
these surfaces become contaminated with
nonvolatile components in the sample.
(2) Dead volume or cold spot in the
injection port.
5. The following list provides possible solutions to correct for tailing.
a. Try baking out the injector and column (see Bake out the GC Injection Port and
Column
in Chapter 8 “Maintenance”).
b. Clean the injection port liner with appropriate solvents (see
GC injection port
Maintenance in Chapter 8 “Maintenance”).
c. Replace the injection port liner with a newly deactivated one (see GC injection
Port Maintenance in Chapter 8 “Maintenance”).
d. Replace the column. Contact your PerkinElmer Service Representative for help.
e. Increase the split flow rate (See
Sample Concentration
in Chapter 5 “Basic
Operation”).
6. A peak may be non-Gaussian if too few data points are obtained. Too few points result from
low sample concentration, low ionization yield, incorrect detector voltage, detector
malfunction, steep temperature gradient in the temperature program, or rapid carrier gas
flow rate.
7. The following list provides additional solutions for correcting peak shape due to low
concentration.
a. Analyze a more concentrated sample.
b. Increase the filament current (increase number of electrons and therefore number
of ions, however, the filament may burn out faster).
c. Increase the detector voltage.
This may help slightly, but the noise increases as well. Too high of a detector
voltage can permanently damage the instrument and will age the detector faster.
d. Replace the detector with a new one.
GC peaks are eluting late
When users notice that the GC peaks are eluting late or early this indicates a change in helium flow
or pressure. A change in helium flow or pressure can be due to several things. If the peaks are
eluting late the following is a list of things for users to verify:
1. Verify the helium source still has an adequate amount of helium. If using the on-board
carrier gas cartridge check the He High Pressure of the system which will indicate if the
cartridge is empty.
To do this:
i Access the Advanced screen (see the Chapter 7 “Advanced Operations” for
instructions).