Distorted peak shape: plant sterol GCMS analysis
Posted: Mon Apr 28, 2025 11:05 am
Hello everyone,
I am analyzing plant sterols (derivatized) in a GCMS intuvo (9000 GC System & 5977C GC/MSD) , and I am facing problems with the shape of the peak (see attached below, peak at 30 min retention time). Before we did the same protocol in a GCMS (7890A GC System & 5975C inert MSD with Triple-Axis Detector) and everything worked fine. We are using the same method and an equivalent column (HP 5 MS UI 30m, 0.25 mm, Intuvo).
Facing this problem we have tried to:
*Change the column
*Change the inlet
*Re-condition the column
*Increase the temperature of the inlet
*Change inlet injection speed (from 100 to 22 mm/s)
*Inject it using a 5:1 split
*Prepare again the standard (cholestanol), and derivatize again.
*Ran different samples to ensure that there was not a problem with the physical inlet itself, and after running samples of VOCs with an SPME, the peak was normal and as expected
Do you have any idea what we could change or do to see a regular peak without this distortion and 5+ min retention time??? We think it has something to do with the inlet but are not sure.
Thank you!!!
Image of peak:
[img]https://imagekit.io/tools/asset-public-link?detail=%7B%22name%22%3A%22Screenshot%202025-04-28%20120707.png%22%2C%22type%22%3A%22image%2Fpng%22%2C%22signedurl_expire%22%3A%222028-04-27T10%3A55%3A36.888Z%22%2C%22signedUrl%22%3A%22https%3A%2F%2Fmedia-hosting.imagekit.io%2F13405ec3bbd7437e%2FScreenshot%25202025-04-28%2520120707.png%3FExpires%3D1840445737%26Key-Pair-Id%3DK2ZIVPTIP2VGHC%26Signature%3DlNKjjBVcNU-KL8RA-z65XE9LgtgYXH6H8dbQ18JzhIQUysq3oAyTYaOE~yOPI0nHBho1ImmCeYM9Vljl~C0YU1i2b8yDVr-qd-hVmRHjyDS37RNwrI8UMFE5efU6VKQSOb45vmFBC50JaTk7j1p69DJ2bJzK3~gYueuDHniTDiCWW0DSTmPjWNZlo5ugYFZAA~TsQiso2ynF59gROEEa9YQkRFLdEAolVc2B8Oe-9U3mdBZe3ofhlXnPKxcrpb1xqWoktbXK7Lg3Wgr7ITv~~uoZ7r24wWiGvpYhH0z2Egslzx3VTJ1A0KXbj01Kv3k-JDCgZU1lETZn5u68m93U5Q__%22%7D[/img]
Method:
Control Information
------- -----------
Sample Inlet : GC
Injection Source : PAL Sampler
Injection Location: Front
Mass Spectrometer : Enabled
PAL3 Sampler
Installed Syringe
Name 8010-0129
Maximum Volume 0.01 mL
Minimum Volume 0.00 mL
Script Parameters
Basic
Tool LS 1
Sample Volume 1 uL
Wait for System Ready At start
Wash Station Wash Station
Wash Vial Depth 40 mm
Waste Port Depth 10 mm
Bottom Sense Off
Height From Bottom of Sample Vial 0.5 mm
Cooled Stack None
Cooled Stack Temperature 20 °C
GC Cycle Time 85 min
Pre Injection
Syringe Fill For Wash 80 %
Wash Aspirate Flow Rate 1 uL/s
Washes with Solvent 1 2
Washes with Solvent 2 2
Washes with Solvent 3 0
Washes with Solvent 4 0
Sample
Sample Vial Penetration Depth 30 mm
Sample Vial Penetration Speed 50 mm/s
Sample Washes 1
Sample Wash Volume 2 uL
Filling Strokes 3
Fill Strokes Volume 3 uL
Filling Strokes Aspirate Flow Rate 5 uL/s
Delay After Filling Strokes 0.5 s
Sample Aspirate Flow Rate 1 uL/s
Sample Post Aspirate Delay 2 s
Air Volume 1 uL
Injection Mode Normal
Injection Signal Mode Plunger Up
Inlet Penetration Depth 42 mm
Inlet Penetration Speed 25 mm/s
Pre Inject Time Delay 0.5 s
Injection Flow Rate 50 uL/s
Post Inject Time Delay 0.5 s
Post Injection
Syringe Fill For Wash 80 %
Wash Aspirate Flow 5 uL/s
Washes with Solvent 1 3
Washes with Solvent 2 3
Washes with Solvent 3 0
Washes with Solvent 4 0
Serial Number Robot
Script Name GC-LIQ-STD-BCR-V7.3
No Sample Prep method has been assigned to this method.
GC
GC Summary
Run Time 69.75 min
Post Run Time 0.5 min
Cycle Time Optimization Fast Cool (default)
Oven
Temperature
Setpoint On
(Initial) 70 °C
Hold Time 0.5 min
Post Run 70 °C
Program
#1 Rate 20 °C/min
#1 Value 255 °C
#1 Hold Time 40 min
#2 Rate 3 °C/min
#2 Value 300 °C
#2 Hold Time 5 min
Equilibration Time 0.5 min
Max Temperature 350 °C
Maximum Temperature Override Disabled
SS Inlet He
Mode Splitless
Heater On 270 °C
Pressure On 10.215 psi
Total Flow On 44 mL/min
Septum Purge Flow On 3 mL/min
Septum Purge Flow Mode Standard
Pre-Run Flow Test Off
Gas Saver On 20 mL/min after 4 min
Purge Flow to Split Vent 40 mL/min at 2 min
Liner Agilent 5190-2294: 990 μL (Split, straight, wool, Ultra Inert)
Column
Column #1
Flow
Setpoint On
(Initial) 1 mL/min
Post Run 1 mL/min
Column Information Agilent 19091S-433UI-INT: US24360210
Description HP-5MS UI
Temperature Range -60 °C—325 °C (350 °C)
Dimensions 30 m x 250 μm x 0.25 μm (Uncalibrated)
Heater Oven
Column lock Unlocked
In SS Inlet He
Out MSD
(Initial) 70 °C
Pressure 10.215 psi
Flow 1 mL/min
Average Velocity 33.891 cm/sec
Holdup Time 1.4753 min
System Holdup 1.5408 min
Control Mode Constant Flow
Column Outlet Pressure 0 psi
Agilent Intuvo 9000 GC Components
Guard Chip
Temperature
Setpoint On
(Initial) 270 °C
Post Run 75 °C
Model Number G4587-60565 (Intuvo SSI Guard Chip)
Track Oven Off
Max Temperature 450 °C
Isothermal Setpoints
Bus Temperature On 200 °C
Use Default Bus Temperature Off
Detector Evaluation
Perform Detector Evaluation Test Off
MSD Transfer Line
Temperature
Setpoint On
(Initial) 280 °C
Signals
Signal #1:
Description None
Signal #2:
Description None
Signal #3:
Description None
Signal #4:
Description None
Signal #5:
Description None
Signal #6:
Description None
Signal #7:
Description None
Signal #8:
Description None
MS Information
-- -----------
JetClean: No Cleaning
General Information
------- -----------
Acquisition Mode : Scan
Solvent Delay (minutes) : 15
Tune file : D:\MassHunter\GCMS\1\5977\etune.u
EM Setting mode Gain : 5.000000
Normal or Fast Scanning : Normal Scanning
Trace Ion Detection : Off
Run Time (if MS only) : 10 minutes
[Scan Parameters]
Start Time : 15
Low Mass : 70
High Mass : 600
Threshold : 150
A/D Samples: : 4
[MSZones]
MS Source : 230 C maximum 250 C
MS Quad : 150 C maximum 200 C
Timed Events
----- ------
Number Events= 0
END OF MS ACQUISITION PARAMETERS
TUNE PARAMETERS for SN: US2302MA11
---------------------------------
Trace Ion Detection is OFF.
34.593 : EMISSION
70.007 : ENERGY
0.503 : REPELLER
89.822 : IONFOCUS
20.181 : ENTRANCE_LENS
1208.936 : EMVOLTS
1438.4 : Actual EMV
5.00 : GAIN FACTOR
2220.000 : AMUGAIN
140.688 : AMUOFFSET
1.000 : FILAMENT
1.000 : DCPOLARITY
10.116 : ENTLENSOFFSET
10.002 : Ion_Body
-3.001 : EXTLENS
-138.000 : MASSGAIN
-20.000 : MASSOFFSET
END OF TUNE PARAMETERS
----------------------
END OF INSTRUMENT CONTROL PARAMETERS
I am analyzing plant sterols (derivatized) in a GCMS intuvo (9000 GC System & 5977C GC/MSD) , and I am facing problems with the shape of the peak (see attached below, peak at 30 min retention time). Before we did the same protocol in a GCMS (7890A GC System & 5975C inert MSD with Triple-Axis Detector) and everything worked fine. We are using the same method and an equivalent column (HP 5 MS UI 30m, 0.25 mm, Intuvo).
Facing this problem we have tried to:
*Change the column
*Change the inlet
*Re-condition the column
*Increase the temperature of the inlet
*Change inlet injection speed (from 100 to 22 mm/s)
*Inject it using a 5:1 split
*Prepare again the standard (cholestanol), and derivatize again.
*Ran different samples to ensure that there was not a problem with the physical inlet itself, and after running samples of VOCs with an SPME, the peak was normal and as expected
Do you have any idea what we could change or do to see a regular peak without this distortion and 5+ min retention time??? We think it has something to do with the inlet but are not sure.
Thank you!!!
Image of peak:
[img]https://imagekit.io/tools/asset-public-link?detail=%7B%22name%22%3A%22Screenshot%202025-04-28%20120707.png%22%2C%22type%22%3A%22image%2Fpng%22%2C%22signedurl_expire%22%3A%222028-04-27T10%3A55%3A36.888Z%22%2C%22signedUrl%22%3A%22https%3A%2F%2Fmedia-hosting.imagekit.io%2F13405ec3bbd7437e%2FScreenshot%25202025-04-28%2520120707.png%3FExpires%3D1840445737%26Key-Pair-Id%3DK2ZIVPTIP2VGHC%26Signature%3DlNKjjBVcNU-KL8RA-z65XE9LgtgYXH6H8dbQ18JzhIQUysq3oAyTYaOE~yOPI0nHBho1ImmCeYM9Vljl~C0YU1i2b8yDVr-qd-hVmRHjyDS37RNwrI8UMFE5efU6VKQSOb45vmFBC50JaTk7j1p69DJ2bJzK3~gYueuDHniTDiCWW0DSTmPjWNZlo5ugYFZAA~TsQiso2ynF59gROEEa9YQkRFLdEAolVc2B8Oe-9U3mdBZe3ofhlXnPKxcrpb1xqWoktbXK7Lg3Wgr7ITv~~uoZ7r24wWiGvpYhH0z2Egslzx3VTJ1A0KXbj01Kv3k-JDCgZU1lETZn5u68m93U5Q__%22%7D[/img]
Method:
Control Information
------- -----------
Sample Inlet : GC
Injection Source : PAL Sampler
Injection Location: Front
Mass Spectrometer : Enabled
PAL3 Sampler
Installed Syringe
Name 8010-0129
Maximum Volume 0.01 mL
Minimum Volume 0.00 mL
Script Parameters
Basic
Tool LS 1
Sample Volume 1 uL
Wait for System Ready At start
Wash Station Wash Station
Wash Vial Depth 40 mm
Waste Port Depth 10 mm
Bottom Sense Off
Height From Bottom of Sample Vial 0.5 mm
Cooled Stack None
Cooled Stack Temperature 20 °C
GC Cycle Time 85 min
Pre Injection
Syringe Fill For Wash 80 %
Wash Aspirate Flow Rate 1 uL/s
Washes with Solvent 1 2
Washes with Solvent 2 2
Washes with Solvent 3 0
Washes with Solvent 4 0
Sample
Sample Vial Penetration Depth 30 mm
Sample Vial Penetration Speed 50 mm/s
Sample Washes 1
Sample Wash Volume 2 uL
Filling Strokes 3
Fill Strokes Volume 3 uL
Filling Strokes Aspirate Flow Rate 5 uL/s
Delay After Filling Strokes 0.5 s
Sample Aspirate Flow Rate 1 uL/s
Sample Post Aspirate Delay 2 s
Air Volume 1 uL
Injection Mode Normal
Injection Signal Mode Plunger Up
Inlet Penetration Depth 42 mm
Inlet Penetration Speed 25 mm/s
Pre Inject Time Delay 0.5 s
Injection Flow Rate 50 uL/s
Post Inject Time Delay 0.5 s
Post Injection
Syringe Fill For Wash 80 %
Wash Aspirate Flow 5 uL/s
Washes with Solvent 1 3
Washes with Solvent 2 3
Washes with Solvent 3 0
Washes with Solvent 4 0
Serial Number Robot
Script Name GC-LIQ-STD-BCR-V7.3
No Sample Prep method has been assigned to this method.
GC
GC Summary
Run Time 69.75 min
Post Run Time 0.5 min
Cycle Time Optimization Fast Cool (default)
Oven
Temperature
Setpoint On
(Initial) 70 °C
Hold Time 0.5 min
Post Run 70 °C
Program
#1 Rate 20 °C/min
#1 Value 255 °C
#1 Hold Time 40 min
#2 Rate 3 °C/min
#2 Value 300 °C
#2 Hold Time 5 min
Equilibration Time 0.5 min
Max Temperature 350 °C
Maximum Temperature Override Disabled
SS Inlet He
Mode Splitless
Heater On 270 °C
Pressure On 10.215 psi
Total Flow On 44 mL/min
Septum Purge Flow On 3 mL/min
Septum Purge Flow Mode Standard
Pre-Run Flow Test Off
Gas Saver On 20 mL/min after 4 min
Purge Flow to Split Vent 40 mL/min at 2 min
Liner Agilent 5190-2294: 990 μL (Split, straight, wool, Ultra Inert)
Column
Column #1
Flow
Setpoint On
(Initial) 1 mL/min
Post Run 1 mL/min
Column Information Agilent 19091S-433UI-INT: US24360210
Description HP-5MS UI
Temperature Range -60 °C—325 °C (350 °C)
Dimensions 30 m x 250 μm x 0.25 μm (Uncalibrated)
Heater Oven
Column lock Unlocked
In SS Inlet He
Out MSD
(Initial) 70 °C
Pressure 10.215 psi
Flow 1 mL/min
Average Velocity 33.891 cm/sec
Holdup Time 1.4753 min
System Holdup 1.5408 min
Control Mode Constant Flow
Column Outlet Pressure 0 psi
Agilent Intuvo 9000 GC Components
Guard Chip
Temperature
Setpoint On
(Initial) 270 °C
Post Run 75 °C
Model Number G4587-60565 (Intuvo SSI Guard Chip)
Track Oven Off
Max Temperature 450 °C
Isothermal Setpoints
Bus Temperature On 200 °C
Use Default Bus Temperature Off
Detector Evaluation
Perform Detector Evaluation Test Off
MSD Transfer Line
Temperature
Setpoint On
(Initial) 280 °C
Signals
Signal #1:
Description None
Signal #2:
Description None
Signal #3:
Description None
Signal #4:
Description None
Signal #5:
Description None
Signal #6:
Description None
Signal #7:
Description None
Signal #8:
Description None
MS Information
-- -----------
JetClean: No Cleaning
General Information
------- -----------
Acquisition Mode : Scan
Solvent Delay (minutes) : 15
Tune file : D:\MassHunter\GCMS\1\5977\etune.u
EM Setting mode Gain : 5.000000
Normal or Fast Scanning : Normal Scanning
Trace Ion Detection : Off
Run Time (if MS only) : 10 minutes
[Scan Parameters]
Start Time : 15
Low Mass : 70
High Mass : 600
Threshold : 150
A/D Samples: : 4
[MSZones]
MS Source : 230 C maximum 250 C
MS Quad : 150 C maximum 200 C
Timed Events
----- ------
Number Events= 0
END OF MS ACQUISITION PARAMETERS
TUNE PARAMETERS for SN: US2302MA11
---------------------------------
Trace Ion Detection is OFF.
34.593 : EMISSION
70.007 : ENERGY
0.503 : REPELLER
89.822 : IONFOCUS
20.181 : ENTRANCE_LENS
1208.936 : EMVOLTS
1438.4 : Actual EMV
5.00 : GAIN FACTOR
2220.000 : AMUGAIN
140.688 : AMUOFFSET
1.000 : FILAMENT
1.000 : DCPOLARITY
10.116 : ENTLENSOFFSET
10.002 : Ion_Body
-3.001 : EXTLENS
-138.000 : MASSGAIN
-20.000 : MASSOFFSET
END OF TUNE PARAMETERS
----------------------
END OF INSTRUMENT CONTROL PARAMETERS