Temperature Vaporization Inlet

Temperature Vaporization Inlet
17 The Programmable Temperature
Vaporization Inlet
Introducing the Agilent PTV
Pulsed modes
Operating modes
Control table parameters—pulsed
split mode
Procedure: Using pulsed split mode
with the column defined
Procedure: Using pulsed split mode
with the column not defined
System requirements
System components
Sampling heads
Columns and Traps
Heating the inlet
Additional temperature ramps
Using the Splitless Modes
Cooling the inlet
Configuring the PTV
Shutdown behavior
Temperature considerations
Cold splitless introduction
Hot splitless introduction
Using the Split Modes
Control table parameters—splitless
operation
Starting values
Procedure: Using splitless mode
with the column defined
Procedure: Using splitless mode
with the column not defined
Flow pattern
Temperature considerations
Cold split introduction
Hot split introduction
Control table parameters—split
mode operation
Procedure: Using split mode with
the column defined
Procedure: Using split mode with
the column not defined
Flow patterns
Pulsed splitless mode operation
Control table parameters—pulsed
splitless operation
Procedure: Using pulsed splitless
mode with the column defined
Procedure: Using pulsed splitless
mode with the column not defined
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The Programmable Temperature Vaporization Inlet
Using the Solvent Vent Mode
Flow patterns
Temperature, pressure, and flow
considerations
Sequence of operations
Timelines
When is Start Run?
Control table parameters—solvent
vent
operation
Procedure: Using solvent vent
mode with the column defined
Procedure: Using solvent vent
mode with the column not defined
Large volume injection
ChemStation requirements
Calculated values
Possible adjustments
Procedure: Cleaning the septumless head
Procedure: Replacing the Teflon
ferrule
The septum head
Procedure: Removing the septum
head
Procedure: Changing the septum
Glass inlet liners
Procedure: Replacing liners
Replacing the split vent trap filter
cartridge
Procedure: Leak testing the gas
plumbing
Procedure: Leak testing the PTV inlet
Correcting leaks
Potential leak points
Consumables and replaceable parts
Maintaining a PTV
Inlet adapters
Procedure: Replacing inlet adapters
Procedure: Installing columns
The septumless head
Procedure: Removing the septumless head
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The Programmable Temperature
Vaporization Inlet
Introducing the Agilent PTV
Operating modes
The Agilent Programmed Temperature Vaporization (PTV) Inlet System has five
operating modes:
•
•
•
•
•
The split mode is generally used for major component analyses.
The pulsed split mode is like the split mode, but with a pressure pulse applied
to the inlet during sample introduction to speed the transfer of material to
the column.
The splitless mode is used for trace analyses.
The pulsed splitless mode allows for a pressure pulse during sample
introduction.
The solvent vent mode is used for large volume injection. Either single or
multiple injections can be made for each run.
System requirements
The PTV inlet can be used with both manual and automatic injection.
For automatic multiple injections (large volume injections), an Agilent GC or
MSD ChemStation is required. This function is not available under 6890 control
alone. See “Using the Solvent Vent Mode” .
System components
1. The pneumatics module, located at the top rear of the GC.
2. The inlet body, always mounted in the front inlet position.
3. The trap, which is in the split line and placed to the left of the pneumatics
carrier at the top rear of the chromatograph.
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Introducing the Agilent PTV
The Programmable Temperature Vaporization Inlet
System components
4. The coolant control valve. For liquid nitrogen, this valve is on the left outside
wall of the oven. For liquid carbon dioxide, it is in the pneumatics carrier.
These valves are not interchangeable—if you change coolants, you must also
change all of the coolant plumbing including the valve and inlet jacket.
5. The thermocouple conversion board. It converts thermocouple readings
from the inlet for use by the GC and is near the trap.
Split vent
Septum purge vent
PV2
SPR
Sol
PS
Trap
Inlet
Carrier
supply
PV1
PV
SPR
Sol
PS
FS
CCV
FS
Pneumatics module
Proportional valve
Septum purge regulator
Solenoid valve
Pressure sensor
Flow sensor
Cryogenic coolant valve
CCV
Coolant
supply
Alternate purge flow paths
With septum head
With septumless head
Figure 56 PTV system components
Sampling heads
Two heads are available for the PTV inlet.
•
The septum head uses either a regular septum or a Merlin Microseal™ to seal
the syringe passage. A stream of gas sweeps the inner side of the septum and
exits through the septum purge vent on the pneumatics module. It may be
used with either automatic or manual injection.
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Introducing the Agilent PTV
Caution
The Programmable Temperature Vaporization Inlet
Heating the inlet
At inlet temperatures below 40°C, the Merlin Microseal may not seal
effectively—use a regular septum instead.
•
The septumless head uses a check valve instead of a septum to seal the
syringe entrance passage. It may be used with either automatic or manual
injection.
Septum head
Septumless head
Carrier gas and septum purge
lines to pneumatics module
Carrier gas line
Note:
Two gas lines (carrier supply
and septum purge), meeting
at the pneumatics module.
Uses either standard 11 mm
septa or (with a different cap)
a Merlin Microseal.
Note:
One gas line (carrier supply).
No septum, so no septum
purge line. Septum purge
stream exits through bypass
line.
Figure 57 Sampling heads
The flow diagrams in the rest of this book show the septum head in place with
a separate drawing for the septumless head plumbing.
Heating the inlet
The control parameters for PTV temperature programming are the same as for
the column oven, but are reached by pressing [Front Inlet]. Temperature can be
programmed with an initial temperature and up to 3 rates and plateaus. Rates
between 0.1 and 720°C/min can be selected. See “Configuring the oven” for
details.
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Introducing the Agilent PTV
Caution
The Programmable Temperature Vaporization Inlet
Heating the inlet
If the initial inlet temperature and the oven initial temperature are too close, the
inlet may be unable to maintain its setpoint. We recommend a difference of at
least 6°C, either higher or lower.
Additional temperature ramps
For most purposes, the PTV is designed to hold the sample in the inlet liner until
the entire sample—there could be several injections—has been injected. Then
the PTV is heated rapidly to transfer the sample to the column. This can be
accomplished with an initial hold, a single ramp, and a hold at the end to complete
sample transfer.
Two additional ramps are available and have several possible uses:
•
•
•
The inlet can be heated to a high temperature to thermally clean the liner for
the next run.
The inlet can be programmed downward—just set the Final temp below the
previous temperature—to reduce thermal stress on the inlet.
Downward programming can be used to prepare the inlet for the next run.
This can reduce cycle time for greater sample throughput.
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Introducing the Agilent PTV
The Programmable Temperature Vaporization Inlet
Cooling the inlet
Cooling the inlet
The sample may be injected into either a cooled or heated chamber. The initial
chamber temperature can be reduced to –60°C (with CO2 cooling) or to –160°C
(with liquid N2 cooling).
Caution
If the initial inlet temperature and the oven initial temperature are too close, the
inlet may be unable to maintain its setpoint. We recommend a difference of at
least 6°C, either higher or lower.
The 6890 GC supports only one type of coolant at a time.
Once a coolant is selected for any cryogenic device, that same coolant must be used for
all such devices, including the column oven.
Since the GC can sense which coolant is used by the oven, if oven cooling is installed
that coolant becomes the one that must be used by all other cooling devices.
Configuring the PTV
To configure the PTV, press [Config] [Front Inlet]. If the inlet has not been
configured previously, this screen is displayed.
1. Press [Config][Front Inlet]
2. Scroll to coolant type
3. Press [Mode/Type]
4. Scroll to coolant used, press [Enter]
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Introducing the Agilent PTV
The Programmable Temperature Vaporization Inlet
Cooling the inlet
If oven cooling is installed, your choices are restricted to the coolant used by the
oven or None. If oven cooling is not installed, you must specify the coolant using
the procedure in the figure.
If the Cryo type selection is anything other than None, several other parameters
appear.
Cryo [ON] enables cryogenic cooling of the inlet as soon as the column oven
reaches its initial temperature. [OFF] disables cooling.
Use cryo temp If Cryo is ON, this is the upper limit of temperatures at which
cryo cooling is used to hold the inlet at its setpoint. If the setpoint is higher than
this limit, cryogenic cooling is used to bring the inlet down to its setpoint but is
not used to hold it at the setpoint.
Cryo timeout Cryo timeout occurs, and the inlet temperature shuts down,
when a run does not start within a specified time (range 5 to 120 minutes, default
30 minutes) after the oven equilibrates. Turning cryo timeout off disables this
feature. We recommend that it be turned on because cryo timeout conserves
coolant at the end of a sequence or if automation fails. A Post Sequence method
could also be used.
Cryo fault Shuts down the inlet temperature if it does not reach setpoint in
16 minutes of continuous cryo operation. Note that this is the time to reach the
setpoint, not the time to stabilize and become ready at the setpoint.
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Introducing the Agilent PTV
The Programmable Temperature Vaporization Inlet
Cooling the inlet
Shutdown behavior
Both Cryo timeout and Cryo fault can cause cryo shutdown. If this happens, the
inlet heater is turned off and the cryo valve closes. The GC beeps and displays
this message:
The inlet heater is monitored to avoid overheating. If the heater remains on at
full power for more than 2 minutes, the heater is shut down. The GC beeps and
displays this message:
To recover from either condition, turn the GC off, then on, or enter a new setpoint.
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Using the Split Modes
The Programmable Temperature Vaporization Inlet
Flow pattern
Using the Split Modes
Flow pattern
The two split modes—with or without a pressure pulse—divide the gas stream
entering the inlet between the column flow, the split vent flow through the
solenoid valve, and the septum purge flow. The ratio of the split vent flow to the
column flow is called the split ratio.
The main figure shows the flows with the septum head. Flows with the
septumless head are the same except that the septum purge flow bypasses the
head (lower left).
Flow
limiting
frit
Total flow
control loop
Pressure
sensor
Septum purge
regulator
PS
SPR
Septum
head
Column head pressure
control loop
FS
Proportional Flow
valve 1 sensor
Trap
Solenoid Proportional
valve 2
valve
open
Septum
purge
vent
Split
vent
Glass liner
Flows with septumless head
PS
To detector
FS
Septumless
head
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Using the Split Modes
The Programmable Temperature Vaporization Inlet
Temperature considerations
Temperature considerations
Cold split introduction
For cold split sample introduction, use an initial inlet temperature below the
normal boiling point of the solvent. If the liner volume is enough to hold all the
vaporized solvent, start the first inlet temperature ramp at 0.1 minutes with a
high heating rate (500°C/min or higher). The final temperature should be high
enough to volatilize the heaviest analytes from the liner and should be held for
at least 5 minutes. A final temperature of 350°C for 5 minutes has proven
sufficient to quantitatively transfer C44.
For larger injection volumes or to eliminate the solvent, hold the initial
temperature long enough to vent the solvent through the Split vent and then
begin the first ramp. Use a fast rate for thermally stable analytes. Slower rates
may help minimize thermal degradation in the inlet.
A single temperature ramp is enough for the injection process. The remaining
ramps may be used to clean the liner or to reduce the inlet temperature in
preparation for the next injection.
Hot split introduction
For hot split introduction, set an initial temperature high enough to volatilize the
analytes. No additional thermal parameters are required as the inlet will maintain
the setpoint throughout the run.
Because of the small liner volume (about 120 microliters), the PTV has a limited
injection capacity with hot split introduction. Injection volumes exceeding 1 µL
in the hot split mode may overflow the inlet causing analytical problems. Cold
split introduction avoids this potential problem.
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Using the Split Modes
The Programmable Temperature Vaporization Inlet
Control table parameters—split mode operation
Control table parameters—split mode operation
The current operating mode—split
Mode:
Temp
Actual and setpoint inlet initial temperatures.
Init time
Rate #
Hold time at the inlet initial temperature.
Temperature program rate for inlet thermal ramps 1, 2, and 3.
Final temp #
Final inlet temperature for ramps 1, 2, and 3.
Final time #
Hold time at Final temp 1, 2, and 3.
Pressure
Actual and setpoint inlet pressure.
Split ratio The ratio of split flow to column flow. Column flow is set at
the Column 1 or Column 2 control table. This line does not appear if your column
is not defined.
Split flow Flow, in mL/min, from the split/purge vent. This line does not
appear if your column is not defined.
Total flow These are the actual and setpoint values of the total flow into
the inlet, which is the sum of the split flow, column flow, and septum purge flow. When
you change the total flow, the split ratio and split flow change while the column flow and
pressure remain the same.
Procedure: Using split mode with the column defined
1. Verify that the column, carrier gas, and flow or pressure program (if used)
are configured correctly. See “Flow and Pressure Control” .
2. Press [Front Inlet].
a. Scroll to Mode: and press [Mode/Type]. Select Split.
Split ratio =
Split flow
Column flow
b. Set the inlet temperature and any desired ramps.
c. If you want a specific split ratio, scroll to Split ratio and enter that
number. The split flow will be calculated and set for you.
d. If you want a specific split flow, scroll to Split flow and enter that
number. The split ratio will be calculated and displayed for you.
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Using the Split Modes
The Programmable Temperature Vaporization Inlet
Control table parameters—split mode operation
e. If desired, turn on Gas saver. Set the Saver time after the injection
time.
Press [Mode/Type]
Only one rate is necessary
for this example.
Additional rates are at the
user’s discretion.
If using gas saver,
set time after injection time.
3. Press [Prep Run] before manually injecting the sample if the Gas Saver is on
(see page 285).
Procedure: Using split mode with the column not defined
1. Verify that the column, carrier gas, and flow or pressure program (if used)
are configured correctly. See “Flow and Pressure Control” .
2. Press [Front Inlet].
a. Set temperature.
b. Set total flow into the inlet. Measure flows out of the split vent and septum
purge vent using a flow meter.
c. Subtract the septum purge flow from Total flow to get split flow.
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Using the Split Modes
The Programmable Temperature Vaporization Inlet
Control table parameters—split mode operation
d. Calculate the split ratio. Adjust as needed.
Press [Mode/Type]
Only one rate is necessary
for this example.
Additional rates are at the
user’s discretion.
Septum purge
Split vent
Front of instrument
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Using the Split Modes
The Programmable Temperature Vaporization Inlet
Pulsed modes
Pulsed modes
The pressure pulse modes (split and splitless) increase inlet pressure just before
the beginning of a run and return it to the normal value after a specified amount
of time. The pressure pulse sweeps the sample out of the inlet and into the column
faster, reducing the chance for sample decomposition in the inlet. If your
chromatography is degraded by the pressure pulse, a retention gap may help
restore peak shape.
You must press the [Prep Run] key before doing manual injections in the pressure
pulse mode.
You can do column pressure and flow programming when in the pressure pulse
mode. However, the pressure pulse will take precedence over the column
pressure or flow ramp.
Actual
pressure
Pressure pulse
Pressure (or flow) program
0
1
2
3
4
Time (min)
5
6
7
8
Figure 58 Pressure pulse and column flow or pressure
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Using the Split Modes
The Programmable Temperature Vaporization Inlet
Control table parameters—pulsed split mode
Control table parameters—pulsed split mode
The current operating mode—pulsed split.
Mode:
Temp
Actual and setpoint inlet temperatures.
Init time
Rate #
Hold time at the initial inlet temperature.
Temperature program rate for inlet thermal ramps 1, 2, and 3.
Final temp #
Final inlet temperature for ramps 1, 2, and 3.
Final time #
Hold time at Final temp 1, 2, and 3.
Pressure Actual and setpoint inlet pressure before and after the pressure
pulse. This is the starting point of a pressure program or the fixed pressure if a
program is not used.
Pulsed pres The inlet pressure you desire at the beginning of a run. The
pressure rises to this setpoint after [Prep Run] is pressed and remains constant
until Pulse time elapses, when it returns to Pressure.
Pulse time
Start Run.
Inlet pressure returns to its normal setpoint at this time after
Split ratio The ratio of split flow to column flow. Column flow is set at
the Column 1 or Column 2 control table. This line does not appear if your column
is not defined.
Split flow Flow, in mL/min from the split/purge vent. This line does not
appear if your column is not defined.
Total flow The total flow into the inlet, the sum of the split flow, column
flow, and septum purge flow. When you change total flow, the split ratio and split
flow change while column flow and pressure remain the same. When a pressure
pulse is used, total flow increases to keep the split ratio constant.
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Using the Split Modes
The Programmable Temperature Vaporization Inlet
Control table parameters—pulsed split mode
Procedure: Using pulsed split mode with the column defined
1. Verify that the column, carrier gas, and flow or pressure program (if used)
are configured correctly. See “Flow and Pressure Control” .
2. Press [Front Inlet].
a. Scroll to Mode: and press [Mode/Type]. Select Pulsed Split.
b. Set the inlet temperature and any desired ramps.
Split ratio =
Split flow
Column flow
c. Enter values for Pulsed Pres and Pulse time.
d. If you want a specific split ratio, scroll to Split ratio and enter that
number. The split flow is calculated and set for you.
e. If you want a specific split flow, scroll to Split flow and enter that
number. The split ratio is calculated and displayed for you.
f.
Turn Gas saver on, if desired. Set the time greater than Pulse time.
Press [Mode/Type]
3. Press [Prep Run] (see page 285) before injecting a sample manually.
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Using the Split Modes
The Programmable Temperature Vaporization Inlet
Control table parameters—pulsed split mode
Procedure: Using pulsed split mode with the column not defined
1. Verify that the column, carrier gas, and flow or pressure program (if used)
are configured correctly. See “Flow and Pressure Control” .
2. Press [Front Inlet].
a. Scroll to Mode: and press [Mode/Type]. Select Pulsed Split.
b. Set the inlet temperature and any desired ramps.
c. Enter values for Pulsed Pres and Pulse time.
d. Set total flow into the inlet. Measure flows out of the split vent and septum
purge vent using a flow meter.
e. Subtract the septum purge flow from Total flow.
f.
Calculate the split ratio. Adjust as needed.
Press [Mode/Type]
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Using the Splitless Modes
The Programmable Temperature Vaporization Inlet
Flow patterns
Using the Splitless Modes
Flow patterns
In these modes—with or without a pressure pulse—the solenoid valve is closed
during injection and vaporization of the sample and stays so while the sample
transfers to the column. At a specified time after injection, the valve opens to
sweep vapors left in the liner out the split vent. This avoids solvent tailing due
to the large inlet volume and small column flow rate. The main figure shows the
flows with the septum head. Flows with the septumless head are the same except
that the septum purge flow bypasses the head (lower left).
Septum purge
regulator
Column head pressure control loop
Flow
limiting
frit
PS
Septum
head
FS
Proportional Flow
valve 1 sensor
SPR
Pressure
sensor
Septum
purge
vent
Split
vent
Trap
Solenoid Proportional
valve 2
valve
closed
With the solenoid valve
closed, the sample and
solvent transfer to the
column.
Glass liner
Flows with septumless head
PS
FS
To detector
Septumless
head
Figure 59 Stage 1. Sample injection
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Using the Splitless Modes
The Programmable Temperature Vaporization Inlet
Flow patterns
Flow
limiting
frit
Total flow
control loop
Pressure
sensor
Septum purge
regulator
PS
SPR
Septum
head
Column head pressure
control loop
FS
Proportional Flow
valve 1 sensor
Split
vent
Trap
Solenoid Proportional
valve 2
valve
open
After the sample has
transferred to the column,
the solenoid valve opens to
purge remaining solvent
vapor from the system.
Glass liner
Flows with septumless head
PS
FS
Septum
purge
vent
To detector
Septumless
head
Figure 60 Stage 2. Purging
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Using the Splitless Modes
The Programmable Temperature Vaporization Inlet
Flow patterns
SPLITLESS OPERATION
Split vent flow
Purge
flow
Saver
flow
Inlet pressure
Inlet is
pressure
controlled
Prep
Run
Start
Run
Purge
Time
Saver
Time
Stop
Run
Post
Time
Stop
Run
Post
Time
Post
Pres
Column flow program
Inlet
Pres
Inlet
temperature
Prep
Run
Start
Run
Purge
Time
Prep
Run
Start
Run
Purge
Time
Final
temp 1
Init
temp
Figure 61
Flows, pressures, and temperatures
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Using the Splitless Modes
The Programmable Temperature Vaporization Inlet
Temperature considerations
Temperature considerations
Cold splitless introduction
For cold splitless introduction, use an initial inlet temperature below the normal
boiling point of the solvent. For most solvents, starting the first inlet temperature
ramp at 0.1 minutes provides good transfer and reproducibility. A program rate
of 500°C/min or higher is appropriate for thermally stable analytes. A final
temperature of 350°C, held for 5 minutes, has quantitatively transferred up to
C44 alkane.
A main advantage of temperature programmability is that the inlet can be heated
gently to transfer delicate analytes. If the oven temperature is initially low enough
to refocus the analytes on the column, the inlet heating rate can be made slower
(e.g., 120°C/min). This reduces thermal degradation from the inlet and can
improve peak shape and quantitation.
For most applications of cold splitless, a single temperature ramp is enough. The
remaining ramps can be used to clean the liner or to decrease the inlet
temperature to prepare for the next injection.
Hot splitless introduction
For hot splitless introduction, select an initial temperature high enough to
volatilize the analytes. No additional temperature parameters are required as the
inlet will maintain the setpoint throughout the run.
Because of the small liner volume (about 120 µL), the PTV cannot contain vapor
resulting from large liquid injection volumes. Injection volumes greater than 1 µL
may overflow vapor from the inlet, causing analysis variations. Cold splitless
introduction avoids this problem.
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Using the Splitless Modes
The Programmable Temperature Vaporization Inlet
Control table parameters—splitless operation
Control table parameters—splitless operation
The current operating mode—splitless.
Mode:
Temp
Actual and setpoint inlet temperatures.
Init time
Rate #
Hold time at the initial inlet temperature.
Temperature program rate for inlet thermal ramps 1, 2, and 3.
Final temp #
Final inlet temperature for ramps 1, 2, and 3.
Final time #
Hold time at Final temp 1, 2, and 3.
Pressure
Actual and setpoint inlet pressure in psi, bar, or kPa
Purge time The time, after the beginning of the run, when you want the purge
valve to open.
Purge flow The flow, in mL/min, from the purge vent, at Purge time. You
will not be able to specify this value if operating with your column not defined.
Total flow The Total flow line displays the actual flow to the inlet during a
Pre-run (Pre-run light is on and not blinking) and during a run before purge time. You
cannot enter a setpoint at these times. At all other times, Total flow will have both
setpoint and actual values.
Starting values
A successful splitless injection consists of these steps:
1. Inject the sample and temperature program the inlet to vaporize it.
2. Use a low column flow and low oven temperature to create a solventsaturated zone at the head of the column.
3. Use this zone to trap and reconcentrate the sample at the head of the column.
4. Wait until all, or at least most, of the sample has transferred to the column.
Then discard the remaining vapor in the inlet—which is mostly solvent—by
opening a purge valve. This eliminates the long solvent tail that this vapor
would otherwise cause.
5. Raise the oven temperature to analyze the sample.
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Using the Splitless Modes
The Programmable Temperature Vaporization Inlet
Control table parameters—splitless operation
Some experimentation is needed to refine the operating conditions. Table 43
provides starting values for the critical parameters.
Table 43
Splitless Mode Inlet Parameters
Parameter
Allowed setpoint range
Suggested starting value
Oven temperature
No cryo, ambient+10° C to 450° C
CO2 cryo, –60° C to 450° C
N2 cryo, –80° C to 450° C
10°C below solvent
boiling point
Oven initial time
0 to 999.9 minutes
≥ Inlet purge time
Inlet purge time
0 to 999.9 minutes
Liner volume* x 5
Column flow
Gas saver time
0 to 999.9 minutes
After purge time
Gas saver flow
15 to 1000 mL/min
15 mL/min greater than
maximum column flow
Inlet temperature
No cryo, oven temp + 10°C
CO2 cryo, –50°C to 450°C
N2 cryo, –60°C to 450°C
10°C below solvent
boiling point for 0.1 min,
then ramp up
* Liner volume is about 120 µL
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Using the Splitless Modes
The Programmable Temperature Vaporization Inlet
Control table parameters—splitless operation
Procedure: Using splitless mode with the column defined
1. Verify that the column, carrier gas, and flow or pressure program (if used)
are configured correctly. See “Flow and Pressure Control” .
2. Press [Front Inlet].
a. Scroll to Mode: and press [Mode/Type]. Select Splitless.
b. Set the inlet temperature and any desired ramps.
c. Enter a purge time and a purge flow.
d. If desired, turn Gas saver on. Make certain the time is set after the purge
flow time.
Press [Mode/Type]
If using gas saver,
set time after purge flow time.
3. Press [Prep Run] (see page 285) before manually injecting a sample.
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Using the Splitless Modes
The Programmable Temperature Vaporization Inlet
Control table parameters—splitless operation
Procedure: Using splitless mode with the column not defined
1. Verify that the column, carrier gas, and flow or pressure program (if used)
are configured correctly. See “Flow and Pressure Control” .
2. Press [Front Inlet].
a. Scroll to Mode: and press [Mode/Type]. Select Splitless.
b. Set the inlet temperature and any desired ramps.
c. Enter a purge time.
d. Set your total flow greater than the column flow plus the septum purge
flow (about 3 to 6 mL/min) to guarantee adequate column flow.
Press [Mode/Type]
3. Press [Prep Run] (see page 285) before manually injecting a sample.
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Using the Splitless Modes
The Programmable Temperature Vaporization Inlet
Pulsed splitless mode operation
Pulsed splitless mode operation
See page 389 for a discussion of the pulsed pressure modes.
Control table parameters—pulsed splitless operation
Mode:
The current operating mode—pulsed splitless.
Temp
Actual and setpoint inlet temperatures.
Init time
Rate #
Hold time at the initial inlet temperature.
Temperature program rate for inlet thermal ramps 1, 2, and 3.
Final temp #
Final inlet temperature for ramps 1, 2, and 3.
Final time #
Hold time at Final temp 1, 2, and 3.
Pressure Actual and setpoint inlet pressure before and after the pressure
pulse. It sets the starting point of a pressure program or the fixed pressure if a
program is not used.
Pulsed pres The inlet pressure you desire at the beginning of a run. The
pressure rises to this setpoint after [Prep Run] is pressed and remains constant
until Pulse time elapses, when it returns to Pressure.
Pulse time
Pressure returns to its normal setpoint at this time.
Purge time The time, after the beginning of the run, that you wish the purge
valve to open. Set purge time 0.1 to 0.5 minutes before pulse time.
Purge flow The flow, in mL/min, from the purge vent, at Purge time. The
column must be defined.
Total flow This is the total flow into the inlet, representing a total of the
column flow and the septum purge flow.
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Using the Splitless Modes
The Programmable Temperature Vaporization Inlet
Pulsed splitless mode operation
Procedure: Using pulsed splitless mode with the column defined
1. Verify that the column, carrier gas, and flow or pressure program (if used)
are configured correctly. See “Flow and Pressure Control” .
2. Press [Front Inlet].
a. Scroll to Mode: and press [Mode/Type]. Select Pulsed Splitless.
b. Set the inlet temperature and any desired ramps.
c. Enter values for Pulsed pres and Pulse time.
d. Enter the Purge time when you wish the purge valve to open.
e. Enter a Purge flow.
f.
Turn Gas saver on, if desired. Set the time after the purge flow time.
Press [Mode/Type]
Set purge time 0.1 to 0.5 minutes
before pressure pulse time.
If using gas saver,
set time after purge flow time.
3. Press [Prep Run] (see page 285) before manually injecting a sample.
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Using the Splitless Modes
The Programmable Temperature Vaporization Inlet
Pulsed splitless mode operation
Procedure: Using pulsed splitless mode with the column not defined
1. Verify that the column, carrier gas, and flow or pressure program (if used)
are configured correctly. See “Flow and Pressure Control” .
2. Press [Front Inlet].
a. Scroll to Mode: and press [Mode/Type]. Select Pulsed Splitless.
b. Set the inlet temperature and any desired ramps.
c. Enter values for Pulsed Pres and Pulse time.
d. Enter the Purge time when you wish the purge valve to open.
e. Enter a Purge flow.
Press [Mode/Type]
Set purge time 0.1 to 0.5 minutes
before pressure pulse time.
3. Press [Prep Run] (see page 285) before manually injecting a sample.
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Using the Solvent Vent Mode
The Programmable Temperature Vaporization Inlet
Flow patterns
Using the Solvent Vent Mode
Flow patterns
The sample is injected into a cold inlet. If conditions are properly chosen and
the sample is suitable, analytes deposit in the inlet liner while the solvent
evaporates and is swept out. Large or multiple injections can be used to
concentrate sample in the inlet before transferring to the column for analysis.
The main figure shows the flows with the septum head. Flows with the
septumless head are the same except that the septum purge flow bypasses the
head (lower left).
Stage 1. Sample and vent
Flow
limiting
frit
Total flow
control loop
Pressure
sensor
Septum purge
regulator
PS
SPR
Septum
head
FS
Proportional Flow
valve 1 sensor
Column head pressure
control loop
Trap
Solenoid Proportional
valve
valve 2
open
During sampling and venting
solenoid valve is open. Inlet is
at Init temp, at or below
solvent boiling point. Solvent
vapors are swept out the vent,
while sample deposits on the
liner walls or packing.
Septum
purge
vent
Split
vent
Glass liner
Flows with septumless head
PS
FS
To detector
Septumless
head
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Using the Solvent Vent Mode
The Programmable Temperature Vaporization Inlet
Flow patterns
Stage 2.
Sample transfer
Septum purge
regulator
Column head pressure control loop
Flow
limiting
frit
Septum
head
PS
Pressure
sensor
SPR
Septum
purge
vent
FS
Proportional Flow
valve 1 sensor
Trap
Solenoid Proportional
valve
valve 2
open
When solvent venting ends,
solenoid valve closes and inlet heats to Final temp 1.
The sample transfers to the
capillary column.
Flows with septumless head
FS
Stage 3.
Split
vent
Glass liner
PS
To detector
Septumless
head
Purge and cleanup
The solenoid valve opens again and the system returns to the Stage 1
configuration but with different setpoints. The PTV inlet is flushed. Additional
ramp rates are available to thermally clean the inlet or to reduce inlet
temperature after sample transfer. This can extend the life of the liner.
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Using the Solvent Vent Mode
The Programmable Temperature Vaporization Inlet
Temperature, pressure, and flow considerations
Temperature, pressure, and flow considerations
The solvent vent mode goes through three distinct pneumatic states; venting,
sample transfer, and purging. The vent portion allows the inlet pressure and the
vent flow to be adjusted to optimize solvent elimination. The transfer state
mimics traditional splitless operation and transports the analytes from the liner
to the column. The purging mode allows the user to prepare the inlet for the next
run.
A fundamental difficulty with solvent vent mode is the potential loss of volatile
analytes with the solvent. Several solutions are possible for this situation:
•
The inlet liner can be packed with a more retentive material, such as Tenax.
This greatly improves volatile analyte recovery but may impact recovery of
higher boiling materials.
• Some of the solvent can be left in the liner when sample transfer begins. The
residual solvent acts like a stationary phase and retains volatile material, but
at the expense of a larger solvent peak.
• The inlet temperature can be reduced. This reduces the vapor pressure of
the volatile analytes and permits higher recoveries.
Solvent removal can be speeded up by:
•
Reducing pressure in the inlet during sample introduction—the Vent
pressure parameter
• Increasing flow through the inlet—the Vent flow parameter
While all these possibilities do complicate use of the PTV, they provide increased
flexibility and new potential to solve difficult problems.
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Using the Solvent Vent Mode
The Programmable Temperature Vaporization Inlet
Sequence of operations
Sequence of operations
These are the steps in a typical analysis using the solvent vent mode.
Step
1
Before injection
Parameter
Value
Flow at split vent
Either Purge flow or Saver flow
Inlet pressure
Derived from column setpoint
The system is resting, with Purge flow (or Saver flow, if on) through the inlet.
2
Prep Run begins
Flow at split vent
Vent flow setpoint
Inlet pressure
Vent pressure setpoint
Setpoints change to prepare for injection. When GC is ready, the sample is injected. Inlet and
oven temperature program Init times begin. Solvent venting and analyte trapping begin.
3
At Vent end time
Flow at split vent
None, solenoid valve closed
Inlet pressure
Column pressure setpoint
Solvent venting ends, analyte transfer begins as inlet heats up.
4
At Purge time
Flow at split vent
Purge flow setpoint
Inlet pressure
Column pressure setpoint
Analyte transfer ends, inlet is purged of residual vapor. Analysis begins.
5
At Saver time
Flow at split vent
Saver flow setpoint
Inlet pressure
Column pressure setpoint
Analysis ends, carrier flow reduced to save gas (if Saver is on).
Some important points
•
The flow through the column is governed by the pressure in the inlet. This
is controlled, during the analysis part of the process, by the flow or pressure
setpoint or program entered for the column.
•
The controlling times must be in the order shown; Vent end time before Purge
time before Saver time.
•
Vent end time must occur before the inlet starts to heat and release analytes.
•
Purge time must occur before the oven begins to heat and move sample
through the column.
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Using the Solvent Vent Mode
The Programmable Temperature Vaporization Inlet
Timelines
Timelines
Time increases downward; all other quantities increase to the right.
Time
Oven temp
Inlet temp
Between runs
Prep Run
Start Run
Init time
Inlet pressure
(Controlled by
column flow or
pressure setpoint
or program)
Vent
pressure
Split vent flow
Saver or
Purge
flow
Vent flow
Vent end time
Init time
i5-23
(Inlet is
pressure
controlled)
Rate 1
Final temp 1
Final time 1
Purge time
Rate 1
Other rates,
temps, and
times, if
desired.
Final temp 1
Final time 1
Purge
flow
(Controlled by
column flow or
pressure setpoint
or program)
Saver time
Other rates,
temps, and
times, if
desired.
Figure 62
Saver
flow
(if on)
Time relationships
408
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Using the Solvent Vent Mode
The Programmable Temperature Vaporization Inlet
When is Start Run?
When is Start Run?
Both the inlet and oven temperature programs begin at Start Run. All times—
such as Purge time—are measured from Start Run. When does Start Run occur?
•
•
•
If the sample is injected manually, Start Run occurs when the user presses
the Start Run key.
If a single injection per run is made using an autosampler, Start Run occurs
when the syringe carrier moves down to make the injection.
If multiple injections per run are made using an autosampler, Start Run
occurs when the syringe carrier moves down to make the first injection of
the set. There are no Start Run signals for the rest of the injections in the set.
These additional injections take time. The inlet and oven temperature
programs, mainly the Init time values, must be adjusted to allow for this.
So must the various time values that control the inlet operation. This is
discussed in more detail under “Large volume injection” .
Control table parameters—solvent vent operation
The current operating mode—solvent vent.
Mode:
Temp
Actual and setpoint initial inlet temperatures.
Init time The time, measured from Start Run, when the initial inlet
temperature hold ends. Usually greater than Vent end time.
Rate #
Temperature program rate for inlet thermal ramps 1, 2, and 3.
Final temp #
Final inlet temperature for ramps 1, 2, and 3.
Final time # Hold time at Final temp 1, 2, and 3. This time is a duration; it
is not measured from Start Run.
Pressure Actual and setpoint inlet pressure before and after the vent period.
It sets the starting point of column head pressure.
Vent pressure The inlet pressure during the vent period. By decreasing the
inlet pressure while venting, solvent elimination proceeds faster. Also, the
pressure reduction decreases the amount of carrier gas—and solvent vapor—
that enters the column during this time.
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Using the Solvent Vent Mode
The Programmable Temperature Vaporization Inlet
Control table parameters—solvent vent operation
Users select from 0 to 100 psig. If 0 is chosen, the inlet uses the lowest pressure
possible at the given vent flow. Table 44 shows approximate values for this
minimum at various vent flows of helium. Pressures less than those in the table
are not possible unless the flow is reduced.
Table 44
Minimum attainable pressures
Vent flow
(mL/min)
Actual vent pressure at
“0“ psig setpoint
Actual vent pressure at
“0” kPa setpoint
50
0.7
5
100
1.3
10
200
2.6
18
500
6.4
44
1000
12.7
88
Vent flow The flow of carrier gas out the split vent during the vent period.
Higher flows sweep the liner more quickly and reduce the time for solvent
elimination. For most columns, 100 mL/min vent flow eliminates solvent at an
acceptable rate but puts minimal material on the column.
Vent end time The time, measured from Start Run, when solvent venting
ends. For large volume injections, this time is normally greater than the time for
the injection to complete.
Purge time The time, measured from Start Run, when sample transfer ends.
It began at Vent end time.
Purge flow
The flow of carrier gas to the inlet beginning at Purge time.
Total flow
The Total flow displays the actual flow to the inlet.
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Using the Solvent Vent Mode
The Programmable Temperature Vaporization Inlet
Control table parameters—solvent vent operation
Procedure: Using solvent vent mode with the column defined
1. Verify that the column, carrier gas, and flow or pressure program (if used)
are configured correctly. See “Flow and Pressure Control” .
2. Press [Front Inlet].
a. Scroll to Mode: and press [Mode/Type]. Select Solvent vent.
b. Enter a vent pressure, a vent flow, and a vent end time.
c. Set the inlet temperature and ramps, as desired.
d. Enter a purge time and a purge flow.
e. If desired, turn Gas saver on. Make certain the time is set after the purge
time.
Press [Mode/Type]
Should be less than Init time.
Must be greater than vent end time.
Must be greater than purge time.
3. Press [Prep Run] (see page 285) before manually injecting a sample.
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Using the Solvent Vent Mode
The Programmable Temperature Vaporization Inlet
Control table parameters—solvent vent operation
Procedure: Using solvent vent mode with the column not defined
1. Verify that the column, carrier gas, and flow or pressure program (if used)
are configured correctly. See “Flow and Pressure Control” .
2. Press [Front Inlet].
a. Scroll to Mode: and press [Mode/Type]. Select Solvent vent.
b. Enter a vent end time and a vent pressure.
c. Set the inlet temperature and ramps, as desired.
d. Enter a purge time. It must be greater than the vent end time.
e. Set total flow greater than the column flow plus the septum purge flow
(about 6 mL/min) to guarantee adequate column flow.
Press [Mode/Type]
Should be less than Init time.
Must be greater than vent end time.
3. Press [Prep Run] (see page 285) before manually injecting a sample.
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Using the Solvent Vent Mode
The Programmable Temperature Vaporization Inlet
Large volume injection
Large volume injection
Most vaporizing inlets are designed for liquid injections in the 1 to 5 µL range.
With larger injections, the vapor cloud created when the sample vaporizes may
overflow the inlet and degrade the chromatography. For the PTV, the nominal
liner liquid capacities are:
Table 45
Liner capacities
Liner
Nominal liquid capacity
Inertness
Open baffle
5 µL
High
Glass wool packed
25 µL
Lower, because of greater surface area
In the solvent vent mode, analytes are thermally trapped in the liner while the
solvent is removed. With the solvent gone, the liner volume can be used for
another injection. Injection can be repeated several times to concentrate the
analytes from a large sample volume. After injection and solvent removal, the
analytes are transferred to the column. This can replace the need for offline
concentrating and minimize loss of sample.
Multiple injections by an automatic sampler can be used with the PTV to achieve
large volume injection. A ChemStation controls the process.
ChemStation requirements
A GC or MSD ChemStation is necessary for multiple injection because the needed
parameters are not available through the 6890 GC keyboard.
•
GC ChemStation Software revision A.04.02 or later
or
Software revision A.04.01 plus the software
provided with the PTV.
•
MSD ChemStation Software revision A.03.00 or later
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Using the Solvent Vent Mode
The Programmable Temperature Vaporization Inlet
Large volume injection
Table 46 Control parameters—Injector configuration subscreen
•
•
•
Parameter
Range
Default
Syringe size
0.1 to 100 µL
10 µL
Nanoliter adapter
Present or not present
Not present
Multiple injections
Single or multiple
Single
Syringe size Full volume of the syringe.
Nanoliter Adapter Controlled by a checkbox. If checked, indicates
that a nanoliter adapter is present on the injector. If not checked, means that
a nanoliter adapter is not present on the injector. The adapter is always present on
the G2613A injector
Multiple Injections Controlled by a checkbox. If checked, the
sampler makes multiple injections into the inlet for each run according to
the other parameters. It issues a Start Run command at the first injection only.
If not checked, the sampler makes one injection—and issues a Start Run
command—for each run. This is the default mode of operation.
Table 47 Control parameters—Injector screen
•
•
•
Parameter
Range
Default
Inject X µL Y times
X: 0.1 to 0.5 × syringe volume
Y: 1 to 100
X: 0.1 × syringe volume
Y: 1
Delay between injections
0 to 100 seconds
0
Preinjection washes
0 to 15
0
Postinjection washes
0 to 15
0
Pumps
0 to 15
0
Inject µL times X is the amount to be injected; Y is the number of
injections to make. If the nanoliter adapter is checked on the Injector Configuration
screen, the range becomes 0.02 to 0.4 x syringe volume.
Delay A pause time, in seconds, between injections. This is added to the
minimum hardware cycle time.
Preinjection washes Number of times to wash the syringe with
solvent and/or sample before the first injection. No washes are performed before
the rest of the injections in a multiple injection set.
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Using the Solvent Vent Mode
•
•
The Programmable Temperature Vaporization Inlet
Large volume injection
Postinjection washes Number of times to wash the syringe with
solvent after the last injection. No washes are performed after the rest of the
injections in a multiple injection set.
Preinjection pumps Number of times to pump the syringe plunger
before drawing up the measured sample. Pump are performed only before
the first injection of a multiple injection set.
Calculated values
The software calculates and displays:
•
•
On the Injector screen: Total Product of X (Volume per injection) and Y
(Injections per run).
On the Inlets screen: Estimated total injection time The
approximate total time, in minutes, to make a set of multiple injections based
on the parameters entered and the mechanical cycle time of the sampler.
Includes Delay between injections, pre- and post-injection dwell
times, and viscosity delays.
An example
These values were used for a sample with a broad range of boiling points.
General parameters
Name
Value
Sample
C10 to C44 hydrocarbons in hexane
Mode
Solvent vent
PTV liner
Glass wool packed
Injection volume
One 10.0 µL injection (25 µL syringe)
Injection speed
Fast
Column
30 m x 320 µm x 0.25 µm -5, p/n 19091J-413
Column flow
4 mL/min constant flow
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Using the Solvent Vent Mode
The Programmable Temperature Vaporization Inlet
Large volume injection
Inlet parameters
Name
Value
Name
Value
Init temp
40°C
Rate 2 (off)
Init time
0.3 min
Pressure
15.6 psig
Rate 1
720°C/min
Vent pressure
0.0 psig
Final temp 1
450°C
Vent flow
100 mL/min
Final time 1
5 min
Vent end time
0.2 min
Rate 2
100°C/min
Purge time
2.0 min
Final temp 2
250°C
Purge flow
50 mL/min
Final time 2
0 min
Oven parameters
Name
Value
Init temp
40°C
Init time
2.5 min
Rate 1
25°C/min
Final temp 1
320°C
Final time 1
10.0 min
Rate 2 (off)
Detector parameters
Name
Value
Detector
FID
Detector temp
400°C
Hydrogen flow
40 mL/min
Air flow
450 mL/min
Makeup (N2)
45 mL/min
416
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Using the Solvent Vent Mode
The Programmable Temperature Vaporization Inlet
Large volume injection
C20
i5-26
Figure 63
Chromatogram from one 10 µL injection
These results were compared with a splitless analysis of the same sample, which
should produce 100% recovery of all analytes. The data showed that, under these
conditions, compounds above C20 were completely recovered and that the recovery
was independent of injection size; Compounds lower than C20 were partially vented
with the solvent.
417
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Using the Solvent Vent Mode
The Programmable Temperature Vaporization Inlet
Large volume injection
Possible adjustments
Depending on what you are trying to accomplish, you have a number of possible
adjustments available.
To eliminate more solvent
•
Increase the vent end time, inlet initial time, and purge time. This will not
affect analytes that are quantitatively trapped but will eliminate more of
the solvent peak.
•
Increase the vent flow to sweep the liner more rapidly with the same inlet
timing. Increasing vent flow raises vent pressure if it is set to 0. This puts
more solvent onto the column.
•
Raise the inlet initial temperature to vaporize more solvent and allow
more to be eliminated. This also increases the loss of volatile analytes
since their vapor pressures also increase.
To improve recovery of low boiling analytes
•
Reduce inlet temperature to lower the vapor pressure of the analytes and
trap them more effectively. This also reduces solvent vapor pressure and
more time will be needed to eliminate it.
•
Use a retentive packing in the liner. Materials such as Tenax permit higher
recovery of volatile analytes but may not release higher boiling
compounds. This must be considered if quantitation on these high boiling
peaks is desired.
•
Leave more solvent in the liner. The solvent acts as a pseudo stationary
phase and helps retain volatile analytes. This must be balanced against
the detector’s tolerance for solvent.
An example—continued
The single injection example shown on the last few pages makes it clear that a
10 µL injection does not overload the glass wool packed liner. This means that
multiple 10 µL injections are possible.
It was decided to make 10 injections per run, each of 10 µL size. This would
increase analytical sensitivity substantially. No adjustments were made to
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Using the Solvent Vent Mode
The Programmable Temperature Vaporization Inlet
Large volume injection
improve recovery of the low boilers since the purpose of this analysis was to
detect and measure the high boiling components.
The ChemStation estimated that 10 injections would require a total of
1.3 minutes. The following timing changes were made:
Parameter
Increased from
To
Inlet Init time
0.3 minutes
1.6 minutes
Vent end time
0.2 minutes
1.5 minutes
Purge time
2.0 minutes
3.0 minutes
Oven Init time
2.5 minutes
3.0 minutes
The result is shown in Figure 27.
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Using the Solvent Vent Mode
The Programmable Temperature Vaporization Inlet
Large volume injection
C20
Figure 64
i5-27
Chromatogram from ten 10 µL injections
420
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Maintaining a PTV
The Programmable Temperature Vaporization Inlet
Inlet adapters
Maintaining a PTV
Inlet adapters
The Graphpak™-2M connector (the inlet adapter) at the bottom of the inlet is
sized to the column diameter. When a different diameter column is to be installed,
the adapter must be changed.
The adapter number is stamped on the side of the adapters. Select the smallest
hole diameter that will accept the column.
Table 48
Inlet adapters
Column ID
Inlet adapter number
Quantity
Part no.
200 µm
31
1
5182-9754
250 µm
45
1
5182-9761
320 µm
45
1
5182-9761
530 µm
70
1
5182-9762
Procedure: Replacing inlet adapters
1. Unscrew the column nut from the adapter. Remove the nut and the column
from the inlet.
2. With a 6 mm wrench, remove the inlet adapter, being careful not to lose the
silver seal inside. Save the adapter for later use.
3. Select the appropriate inlet adapter for the column to be installed. Insert a
new silver seal (part number 5182-9763, pkg of 5) into the adapter and screw
the adapter onto the inlet finger tight. Use the 6 mm wrench to tighten the
adapter an additional 1/16- to 1/8-turn.
Do not overtighten the adapter. The inlet can be damaged if the adapter is
forced. If the adapter leaks, check the silver seal and replace it if necessary.
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Maintaining a PTV
The Programmable Temperature Vaporization Inlet
Inlet adapters
Procedure: Installing columns
Graphpak-2M ferrules are sized to the column outer diameter.
Table 49
Columns and ferrules
Column ID
Graphpak ferrule hole ID
Quantity
Part no.
200 µm
0.31 mm
10
5182-9756
250 µm
0.40 mm
10
5182-9768
320 µm
0.45 mm
10
5182-9769
530 µm
0.70 mm
10
5182-9770
1. Place the appropriate Graphpak ferrule onto the column inlet end and pull
it at least 30 mm from the end.
2. With a glass knife or other fused silica cutter, remove approximately 10 mm
from the column end to eliminate graphite contamination.
3. Position the ferrule so that it is 17 mm from the column end. Place a small
mark (typewriter correction fluid is useful) at the back of the ferrule and,
making sure that the column is correctly positioned, insert the column end
into the adapter.
2
cm
17 mm
0
Mark column here
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Maintaining a PTV
The Programmable Temperature Vaporization Inlet
The septumless head
4. Screw the column nut on finger tight. Using a 5 mm wrench, tighten the
column nut 1/8- to 1/4-turn. Be careful not to overtighten.
5. Check the connections for leaks. If there are any leaks at the column adapter,
tighten it slightly more with the open end wrench provided.
The septumless head
This sampling head uses a check valve instead of a septum to seal the syringe
entrance passage. It may be used with either automatic or manual injection.
Syringes must have 23 gauge needles (see “Consumables and replaceable parts” ).
Procedure: Removing the septumless head
1. Cool the inlet to room temperature.
2. Disconnect the carrier gas line.
3. Unscrew the septumless head counterclockwise from the inlet.
4. Screw the new head onto the inlet. Tighten it 1/8-turn past finger tight.
Carrier gas connection
5. Reconnect the carrier gas line.
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Maintaining a PTV
The Programmable Temperature Vaporization Inlet
The septumless head
6. Check all connections on the sampling head for leaks. If necessary, tighten
them again by hand.
Procedure: Cleaning the septumless head
Minor deposits from sample mixtures can collect in the head. Dust and abraded
material particles can enter together with the syringe needle, eventually causing
leaks. We recommend periodic cleaning.
1. Cool the inlet to room temperature.
2. Disconnect the carrier gas line and unscrew the head from the inlet.
3. Unscrew the sealing element from the head. Carefully remove the Viton seal
and the pressure spring.
Guide cap
Teflon ferrule, 5182-9748
Kalrez seal, 5182-9759
Valve body, 5182-9757
Carrier gas line
Pressure spring, 5182-9758
Viton seal, 5182-9775
Sealing element, 5182-9760
4. Unscrew the guide cap from the head and remove the Teflon ferrule.
Caution
Do not use a sharp object to extract the valve body—this can leave scratches that cause
leaks.
5. Insert a syringe with a 23 gauge needle carefully into the head to press the
valve body with the Kalrez seal slightly out of the head. Carefully tap the head
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Maintaining a PTV
The Programmable Temperature Vaporization Inlet
The septumless head
on a soft smooth surface so that the valve body falls out
completely or slips so far out that you can grasp it with your fingers.
6. Remove the seal from the valve body.
7. Carefully clean all components in hexane.
8. Assemble the head in reverse order. Make sure that you work absolutely lintfree and that the seals and the pressure spring are not damaged.
9. Use this opportunity to check the Teflon ferrule. If it must be replaced, see
page 426 for instructions.
10. Check the entire system again for leaks; if necessary, carefully retighten the
guide cap slightly more with the syringe needle inserted and/or replace the
Kalrez seal.
If the head leaks when a syringe is inserted, the Teflon ferrule is the problem.
If the head leaks without a syringe inserted, the seals may need to be replaced.
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Maintaining a PTV
The Programmable Temperature Vaporization Inlet
The septumless head
Procedure: Replacing the Teflon ferrule
1. Unscrew the guide cap from the septumless head and remove the Teflon
ferrule.
2. Push the guide cap and the new Teflon ferrule over the syringe needle so that
at least 10 mm of the needle tip is exposed.
3. Guide the end of the syringe needle into the septumless head until the ferrule
meets the septumless head.
4. Tighten the guide cap until resistance is first felt.
5. Check for leaks when the syringe needle has been fully introduced.
6. If necessary, carefully tighten the guide cap until the inlet stops leaking.
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Maintaining a PTV
The Programmable Temperature Vaporization Inlet
The septum head
The septum head
The septum head uses either a regular septum or a Merlin Microseal to seal the
syringe passage. A stream of gas sweeps the inner side of the septum and exits
through the septum purge vent on the pneumatics module.
Retaining nut
Procedure: Removing the septum head
The septum head connects to the inlet via a free-spinning retaining nut.
1. Cool the inlet to room temperature.
2. Use a 5/8-inch wrench to loosen the retaining nut on the septum head.
3. Gently remove the septum head assembly from the inlet. Be careful not to
overly bend the 1/16-inch lines. For best results, lift the head to clear the inlet and
then push it to either side to allow access.
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Maintaining a PTV
The Programmable Temperature Vaporization Inlet
The septum head
4. To reinstall the septum head, gently align the head with the inlet and manually
engage the free-spinning nut to the inlet.
The nut should easily turn on to the inlet. If resistance is felt, unscrew the
nut and retry. Excessive force can irreparably damage the inlet.
5. Tighten the retaining nut ½-turn past finger tight.
6. Check all connections for leaks. If necessary, the retaining nut can be
tightened an additional ¼-turn to eliminate leaks.
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Maintaining a PTV
The Programmable Temperature Vaporization Inlet
The septum head
Procedure: Changing the septum
Either a regular septum or a Merlin Microseal can be used with the septum head.
If the inlet temperature is set below 40°C, the Merlin Microseal may not seal
effectively. For inlet temperatures below 40°C, use a regular septum for the inlet
seal.
1. To replace the septum, cool the inlet to ambient temperature.
2. Using the inlet tool or manually, unscrew the septum cap or Merlin cap
counterclockwise. If the septum head begins to turn, support it manually
while removing the cap.
3. Remove the septum or Merlin Microseal, taking care not to scratch the
interior of the septum head.
4. Install a new septum or Merlin Microseal and the correct cap. When installing
a Merlin Microseal, note that the side where the metal parts are visible goes
down.
Merlin
Microseal
and cap
Standard
septum
and cap
5. Check for leaks out of the cap and tighten the cap if necessary.
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Maintaining a PTV
The Programmable Temperature Vaporization Inlet
Glass inlet liners
Glass inlet liners
The liner is the chamber for sample deposition. Three kinds are available:
Table 50.
Inlet liners
Type
Injection
capacity
Inertness
Quantity
Part no.
Open baffled liner
Lowest capacity
Most inert
10
5182-9751
Liner packed with
silanized glass wool
Higher capacity
Less inert
10
5182-9752
Unpacked liner, to be
packed by the user
Depends on the packing
10
5182-9753
Type
Injection
capacity
Glass wool
packing*
Typical
application
Single baffle liner
180 µL
Borosilicate
deactivated
Yes
Large volume
injection, not for
extremely active
compounds
5183-2038
Single baffle liner
200 µL
Borosilicate
deactivated
No
General purpose
5183-2036
Multi baffle liner
150 µL
Borosilicate
deactivated
No
Active
compounds,
drugs, pesticides
5183-2037
Fritted glass liner
150 µL
Borosilicate
deactivated
No
Large volume
injection, all but
the most active
compounds
5183-2041
Glass type
Part no.
*Silanized glass wool 10 gm (pesticide grade) part no. 5181-3317
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Maintaining a PTV
The Programmable Temperature Vaporization Inlet
Glass inlet liners
Procedure: Replacing liners
1. Remove the head from the inlet. See “Procedure: Removing the septumless
head” or “Procedure: Removing the septum head” .
2. Grasp the liner by the Graphpak ferrule. Remove the liner and ferrule.
3. Unscrew the assembly tool (part number G2617-80540) into two pieces, the
ferrule guide and the compression fitting.
Ferrule guide
Graphpak-3D ferrule
Compression
fitting
Open baffle liner
4. Slide the compression fitting onto the longer straight end of the new liner
with the threads pointing toward the end of the liner.
5. Place a Graphpak-3D ferrule on the same end of the liner with the recessed
graphite end towards the compression fitting. Slide the ferrule on so that
about 2 mm of liner is exposed beyond the ferrule.
6. Slide the compression fitting up to meet the ferrule. Screw the ferrule guide
gently onto the compression fitting until it is finger tight.
7. Unscrew and remove the ferrule guide. Slide the compression fitting off the
other end of the liner. The ferrule should now be set with 1 mm of liner
exposed. Check that the graphite within the ferrule is flush with the top of
the metal collar.
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Maintaining a PTV
The Programmable Temperature Vaporization Inlet
Glass inlet liners
8. Insert the glass liner into the inlet from above until the unpacked side of the
ferrule rests on the top of the inlet.
9. Replace the sampling head and reconnect the lines, if necessary.
10. Check all connections for leaks. If necessary, tighten them again by hand.
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Maintaining a PTV
The Programmable Temperature Vaporization Inlet
Glass inlet liners
Replacing the split vent trap filter cartridge
WARNING
Turn off the oven and turn off the heater for the inlet that uses the split vent trap
and let them cool down. Turn off the carrier gas supply pressure.
The split vent trap may contain residual amounts of any samples or other
chemicals you have run through the GC. Follow appropriate safety procedures
for handling these types of substances while replacing the trap filter cartridge.
1. Turn off the inlet and the oven and allow to cool.
2. Set all GC flows to zero.
3. Remove the pneumatics cover.
4. Lift the filter trap assembly form the mounting bracket and unscrew the filter
trap assembly.
Split vent back weldment
Replacement filter kit
Filter cartridge
Split vent front
weldment
O-rings (2)
Flow
5. Remove the old filter cartridge and O-rings and replace them.
6. Reassemble the trap.
7. Check for leaks.
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Maintaining a PTV
The Programmable Temperature Vaporization Inlet
Glass inlet liners
Procedure: Leak testing the gas plumbing
Leaks in the gas plumbing can affect chromatographic results dramatically. The
following procedure checks the flow system up to but not including the inlet
flow manifold. If this portion of the system proves to be leak-free, refer to the
next procedure to check the inlet and inlet manifold.
Liquid leak detectors are not recommended, especially in areas where
cleanliness is very important.
If you do use leak detection fluid, immediately rinse the fluid off to remove the
soapy film.
WARNING
To avoid a potential shock hazard when using liquid detection fluid, turn the GC
off and disconnect the main power cord. Be careful not to spill leak solution on
electrical leads, especially the detector heater leads.
Materials needed:
•
Electronic leak detector capable of detecting your gas type or liquid leak
detection fluid. If you use leak detection fluid, remove excess fluid when you
have completed the test.
•
Two 7/16-inch wrenches
1. Using the leak detector, check each connection you have made, for leaks.
2. Correct leaks by tightening the connections. Retest the connections;
continue tightening until all connections are leak-free.
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Maintaining a PTV
The Programmable Temperature Vaporization Inlet
Glass inlet liners
Procedure: Leak testing the PTV inlet
There are numerous places in the inlet that can leak. This procedure lets you
determine, in general, if there is an unacceptable leak in the inlet. If the inlet is
leaking, you should use an electronic leak detector to pinpoint the component
that is leaking.
WARNING
Be careful! The oven and/or inlet may be hot enough to cause burns.
Materials needed:
•
•
•
•
•
•
•
No-hole ferrule
7/16-inch wrench
Gloves (if the inlet is hot)
Septum nut wrench (part no. 19251-00100)
9/16-inch wrench
1/8-inch SWAGELOK cap
Bubble flow meter
1. Complete the following preliminary steps:
•
If you have entered parameters that you do not want to lose, store them
as a method.
•
Turn the oven off.
•
Cool the oven and inlet to room temperature.
•
Turn the inlet pressure off.
•
Remove the column, if one is installed, and plug the column fitting with
the column nut and a no-hole ferrule.
•
Remove the old septum and replace it with a new one. For instructions,
see “Procedure: Changing the septum” .
2. Remove the column from the inlet fitting on the inside of the oven.
3. If a septum head is installed, and the quality of the septum (or Microseal)
and Graphpak-3D ferrule on the glass liner are unknown, replace them now.
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Maintaining a PTV
The Programmable Temperature Vaporization Inlet
Glass inlet liners
4. Cap the inlet’s column fitting and the septum purge vent (septum head only).
Use solid (no hole) Vespel type ferrules 1/8-inch (part no. 0100-1372) and
1⁄ 16-inch (part no. 5181-7458) with a 1/8-inch Swagelok nut
(part no. 5180-4103) and a capillary column nut.
As alternate capping devices, a 1/8-inch Swagelok cap can be used for the
septum purge vent. A capillary column nut with a solid piece of wire the size
of a paper clip and a 0.5 mm ID graphite ferrule may be used for the inlet
column fitting.
Figure 65
Capping the bottom of the inlet and septum purge vent
5. Make sure that the carrier gas source pressure is at least 35 psi. Carrier source
pressure should always be at least 10 psi greater than the desired inlet
pressure.
6. Configure the inlet for the test. Press [Front Inlet] (or [Back Inlet])
and:
•
Set the inlet to “Split Mode.”
•
Configure the column as 0 length. Press [Config] [Column 1] or
[Config] [Column 2] and enter “0” in the first column of the “Dim”
field.
•
Set the inlet’s Total Flow to 60 mL/min.
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Maintaining a PTV
The Programmable Temperature Vaporization Inlet
Glass inlet liners
•
Set the pressure to 25 psi.
•
Set the inlet temperature to its normal operating temperature.
7. Wait approximately 15 seconds for equilibration.
If pressure cannot be achieved, either a very large leak is present in the
system, or the supply pressure is not high enough.
8. Turn the inlet pressure “Off.”
Press [Front Inlet] (or [Back Inlet]), scroll to the “Pressure” field,
and press [Off]. Both the flow controller and the back pressure valves will
close.
9. Note the “Actual” reading on the display and monitor the pressure for
10 minutes.
•
If there is less than 0.5 psi pressure loss, consider the system leak tight.
•
If pressure loss is much greater than 0.5 psi, there is a leak that must be
found and corrected. Note, however, that you may want to slightly
decrease the leak test time based on the internal inlet volume which
changes with the liner type used (smaller volumes = shorter acceptable
leak test times). See “Correcting leaks” .
10. When the system is considered leak tight, the caps may be removed, the
column reinstalled, its dimensions configured at keyboard, and the desired
pressure and flow rate set.
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Maintaining a PTV
The Programmable Temperature Vaporization Inlet
Glass inlet liners
Correcting leaks
Use an electronic leak detector to check all areas of the inlet and plumbing that
are potential sources of a leak.
Tighten loose connections to correct leaks, if necessary. You may need to repeat
the leak test.
If the pressure drop is now 0.5 psi or less, you can consider the inlet system leak–
free. If the pressure drops faster than the acceptable rate, continue to search for
leaks and repeat the pressure test.
Potential leak points
Check the following areas when checking an inlet system for leaks.
In the oven
• Make sure the bottom of the inlet is correctly capped.
On the inlet
• Septum (septum head only)
• Lower inlet seal at bottom of inlet
• Ferrule on inlet liner
• Connections for carrier gas, septum purge (septum head only)
At EPC module
•
•
•
•
O-rings behind the block where the inlet’s pneumatic lines enter the module
Septum purge cap (septum head only)
Chemical trap O-rings
O-rings in gang fitting
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Maintaining a PTV
The Programmable Temperature Vaporization Inlet
Consumables and replaceable parts
Consumables and replaceable parts
Description
Quantity
Part no.
Septumless head assembly
1
G2617-60507
Service kit
1
5182-9747
Valve body
1
5182-9757
Pressure spring
1
5182-9758
Kalrez seal
1
5182-9759
Teflon guide
1
5182-9748
Sealing element
1
5182-9760
Graphpak-3D ferrule for liners
5
5182-9749
Assembly tool for Graphpak-3D ferrules
1
G2617-80540
Single baffle liner
1
5183-2038
Single baffle liner
1
5183-2036
Multi baffle liner
1
5183-2037
Fritted glass liner
5183-2041
Graphpak-2M inlet adapter, 0.2 mm column id
1
5182-9754
Graphpak-2M inlet adapter, 0.32/0.25 mm column id
1
5182-9761
Graphpak-2M inlet adapter, 0.53 mm column id
1
5182-9762
Silver seal for Graphpak-2M inlet adapter
5
5182-9763
Nut for Graphpak inlet adapters
5
5062-3525
Ferrules for Graphpak-2M inlet adapter, 0.2 mm column id
10
5182-9756
Ferrules for Graphpak-2M inlet adapter, 0.25 mm column id
10
5182-9768
Ferrules for Graphpak-2M inlet adapter, 0.32 mm column id
10
5182-9769
Ferrules for Graphpak-2M inlet adapter, 0.53 mm column id
10
5182-9770
more>
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Maintaining a PTV
The Programmable Temperature Vaporization Inlet
Consumables and replaceable parts
Description
Quantity
Part no.
5 µL, 23 gauge fixed needle
1
9301-0892
10 µL, 23 gauge fixed needle
1
9301-0713
10 µL, Teflon-tipped plunger, 23 gauge fixed needle
1
5181-8809
10 µL, Teflon-tipped plunger, 23 gauge removable needle
1
5181-8813
25 µL, Teflon-tipped plunger, 23 gauge fixed needle
1
5183-0316
25 µL, Teflon-tipped plunger, 23 gauge removable needle
1
5183-0317
50 µL, Teflon-tipped plunger, 23 gauge fixed needle
1
5183-0318
50 µL, Teflon-tipped plunger, 23 gauge removable needle
1
5183-0319
Merlin Microseal starter kit (cap + 1 microseal)
1
5182-3442
Merlin Microseal replacement
1
5182-3444
11 mm septa, red
25
5181-1263
Syringes
Septa and seals
440
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