• State Not Answered
  • Replies 5 replies
  • Subscribers 9 subscribers
  • Views 254 views
  • Users 0 members are here
Related

Agilent Knowledge Portal

Find maintenance, best practice, and troubleshooting articles.

Agilent Knowledge Portal

Loss of sensitivity after instrument vent and column change 7250 GC/Q-TOF

HawkFan

I vented and changed columns recently and have noticed at least a ten fold loss of sensitivity.  The retention times and peak shape seems to be similar to what I have had in the past. I ran the Air and Water Check and passed. I have no issues calibrating and the calibrant sensitivity is the same as it was before, so I expect the problem is with the sample getting to the MS? I'm using 2, 15m columns connected with a PSD.  Would there be any other diagnostics test that I should be using to trouble shoot? Thanks for any thoughts. 

  • 0

    How far is the column installed up into the injection port?  How far is the column installed out of the transferline tipseal into the MS?  When did you last do full injection port maintenance? In the autotune reports, is the filament current different before/after the columns were replaced?   Autotune adjusts parameters to get the results into programmed ranges and the algorithm compensates for changes.  Were both columns the same as the old ones?  Are they cut properly and have new ferrules at the Purged Ultimate Union?  Did you change the column configuration for the new ones?  Are the columns calibrated in MassHunter Acquisition?    Are the vacuum readings different than before?

    Could you share the contents of the acqmeth.txt file that is in your run method's Windows subdirectory along with a tune report?

  • 0 in reply to paulsalverda

    Maintenance on the injection port was done a month ago and only around 50 injections since then. I went head and replaced the liner and double checked the column.  I noticed that the column did slip when being installed and was into the injection port about 4x as far as it should have been.  The filament current was the same before and after the column install.  The column is the same and new ferrules were used.  I did not calibrate the columns in MassHunter Acquisition.  The column is from Agilent and selected them from the "Select from Catalog" option in the method.  The vacuum readings are the same as before I vented.  I'm running a standard now and hope that changing the length of the column going into the injection port solves the problem.  Thanks

    Fullscreen 3162.acqmeth.txt Download 
                          INSTRUMENT CONTROL PARAMETERS:    GC QTOF
                      -----------------------------------------

   D:\MassHunter\GCMS\1\methods\Pesticide_Split_50_Training101323.M
      Sun Nov 10 21:50:42 2024

Control Information
------- -----------

Sample Inlet             : GC
Injection Source         : GC ALS
Injection Location:  Front
Mass Spectrometer        : Enabled


 No Sample Prep method has been assigned to this method.


GC
GC Summary
Run Time                                     15.875 min
Post Run Time                                2 min

Oven
Temperature
Setpoint                                     On
(Initial)                                    90 °C
Hold Time                                    1 min
Post Run                                     280 °C
Program
#1 Rate                                      10 °C/min
#1 Value                                     225 °C
#1 Hold Time                                 0 min
#2 Rate                                      40 °C/min
#2 Value                                     280 °C
#2 Hold Time                                 0 min


Equilibration Time                           1 min
Max Temperature                              320 °C
Maximum Temperature Override                 Disabled
Slow Fan                                     Disabled

ALS
Front Injector
Syringe Size                                 10 μL
Injection Volume                             1 μL
Solvent A Washes (PreInj)                    3
Solvent A Washes (PostInj)                   3
Solvent A Volume                             8 μL
Solvent B Washes (PreInj)                    3
Solvent B Washes (PostInj)                   3
Solvent B Volume                             8 μL
Sample Washes                                1
Sample Wash Volume                           8 μL
Sample Pumps                                 6
Dwell Time (PreInj)                          0 min
Dwell Time (PostInj)                         0 min
Solvent Wash Draw Speed                      300 μL/min
Solvent Wash Dispense Speed                  3000 μL/min
Sample Wash Draw Speed                       300 μL/min
Sample Wash Dispense Speed                   3000 μL/min
Injection Draw Speed                         300 μL/min
Injection Dispense Speed                     6000 μL/min
Viscosity Delay                              2 sec
Sample Depth                                 Disabled
Injection Type                               Standard
L1 Airgap                                    0.2 μL
Solvent Wash Mode                            A,B

Sample Overlap
Mode                                         Sample overlap is not enabled

ALS Errors                                   Pause for user interaction

Front SS Inlet He
Mode                                         Split
Heater                                       On    250 °C
Pressure                                     On    11.157 psi
Total Flow                                   On    56 mL/min
Septum Purge Flow                            On    5 mL/min
Pre-Run Flow Test                            Off
Gas Saver                                    On    15 mL/min after 2 min
Split Ratio                                  50 :1
Split Flow                                   50 mL/min
Liner                                        Agilent 5190-2295: 870 μL (Split, taper, wool, low pressure drop)

Column
Column #1
Flow
Setpoint                                     On
(Initial)                                    1 mL/min
Post Run                                     -4.273 mL/min

Column Information                           Agilent 19091S-431UI: us2702611a
Description                                  HP-5ms Ultra Inert
Temperature Range                            -60 °C—325 °C (350 °C)
Dimensions                                   15 m x 250 μm x 0.25 μm (Uncalibrated)
Heater                                       Oven
Column lock                                  Unlocked
In                                           Front SS Inlet He
Out                                          PSD 1 
(Initial)                                    90 °C
Pressure                                     11.157 psi
Flow                                         1 mL/min
Average Velocity                             26.949 cm/sec
Holdup Time                                  0.92769 min
Control Mode                                 Constant Flow

Column #2
Flow
Setpoint                                     On
(Initial)                                    1.2 mL/min
Post Run                                     4.712 mL/min

Column Information                           Agilent 19091S-431UI: US2407041B-2
Description                                  HP-5ms Ultra Inert
Temperature Range                            -60 °C—325 °C (350 °C)
Dimensions                                   15 m x 250 μm x 0.25 μm (Uncalibrated)
Heater                                       Oven
Column lock                                  Unlocked
In                                           PSD 1 He
Out                                          MSD 
(Initial)                                    90 °C
Pressure                                     4.3978 psi
Flow                                         1.2 mL/min
Average Velocity                             57.524 cm/sec
Holdup Time                                  0.4346 min
Control Mode                                 Constant Flow

Column Outlet Pressure                       0 psi

Detector Evaluation
Perform Detector Evaluation Test             Off

MSD Transfer Line
Temperature
Setpoint                                     On
(Initial)                                    280 °C


Collision Cell/Aux
Pressure
Setpoint                                     Off
(Initial)                                    10 psi
Post Run                                     10 psi

Quench Gas He                                On    4 mL/min
Collision Gas N2                             On    1 mL/min
Collision Cell Aux He                        (unused)

PSD 1
PSD Purge                                    On    5 mL/min
PSD 1 He                                     Supplies Column 2

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






                        END OF INSTRUMENT CONTROL PARAMETERS
                        ------------------------------------

  • 0 in reply to HawkFan

    It is rare that I have so few method recommendations!  Well done.  Please increase the Gas Saver flow to 20 ml/min or even 25 ml/min.  If that flow is too low there is a chance that air can diffuse into the inlet subsystem and damage the columns.

    That's a Mass Calibration Report and not an autotune.

    If the column is way too high in the liner especially in split mode, the sample can vaporize below the end and be mostly swept away. I'm a fan of about 8mm of column sticking up past the ferrule during column installation in a Split/Splitless injection port.

    Does your lab have two 7250s...US2003E302 - the one in this MassCal report and US2013E302 ?   

  • 0 in reply to paulsalverda

    I attached the autotune file now, sorry about that.  I was using split mode so hopefully explains the loss of signal. We only have one instrument, and it is US2003E302. Thanks for the help

     

  • 0 in reply to HawkFan

    Thank you, that cleared up something that had bothered me since it was installed!

    Tune looks great. 

Was this helpful?
Privacy Statement
Terms of Use
Contact Us
Site Help