Shimadzu GC-2014, Instruction Manual

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5 Analysis
5.2 Notes for Analysis
64
GC-2014
Q
Setting the heated zone temperatures
The temperature of the injection port, the column oven and the detector are set individually.
Usually, the injection port and the detector are set to a temperature 20 °C higher than the
column.
Never set the column temperature higher than the detector because the detector could
become contaminated.
When creating a temperature program, be careful not to set the final oven temperature
higher than that of the detector.
Q
Column temperature program
Use a temperature program mainly to analyze samples with a wide boiling point range.
When developing analytical conditions for an unknown sample or a sample which will gener-
ate an unpredictable elution attend, use an initial program with a temperature increase rate
of approximately 10 °C/min. Based on the results, check the temperature range in which the
peaks appear, then examine the analytical conditions. This procedure facilitates time pro-
gram development.
Q
Injection counter
The injection port septum and the glass insert are required to be inspected and replaced
periodically. The GC-2014 probides a function which counts the number of injections. When
the number of injections exceeds the limit, you are prompted to perform maintenance. (What
is actually counted is the number of START times.)
Select the analysis counter on the [DIAG] key screen to set and reset the counter limit. Set
the limit to perform maintenance on a regular basis.
The septum/glass insert replacement cycle varies, depending on the analytical conditions
and samples. If the glass insert is easily contaminated (when analyzing non-volatile com-
punds for example), set a low counter limit. On the other hand, when analyzing cleaner sam-
ples, the limit can be increased.
Q
Starting up the GC
Turn on the power and/or press the [SYSTEM] key to display the GC starup screen. On this
screen, specify the files used for instrument startup and instrument cleaning (column bake -
out).
Press [Start GC] (PF menu) to start temperature control of each heated zone accoding to the
parameters set in the file.
A start up method should be used to initialize the system once it has been turned on. Set the
start up method to “auto” to start the file as soon as the power is on; this helps with instru-
ment recovery after a power failure.
The initial step in the startup method should be turning on the carrier gas flow. After a set
time, increase the injection port and detector temperatures. The column oven temperature
can then be set to increase. The oven temperature increases last to protect the column from
damate and the detctor from contamination. The GC-2014 is designed to control the temper-
atures so that the column temperature never exceeds the detector temperature, even if all
temperatures are set to increase at the same time.
A clean up method uses higher oven temperatures than those used for the analysis. After
set bake-out time, return the temperatures to their normal analytical parameter.