Retention time shifts and loss of repeatability

Hi everyone,

Can somebody advice me on what could be possible cause of retention time shift and unstable areas (meaning poor repeatability) in GCMS? I have included picture below where day1 and day2 means that standards were run in different days. Is that a normal behaviour? Our system is INTUVO GCMS thus we are not cutting our columns or anything like that because we are using guard chips instead.

The GC method is attached as text file

                        INSTRUMENT CONTROL PARAMETERS:    GCMS
                        --------------------------------------

      Fri May 27 14:00:29 2022

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                                     16 min
Post Run Time                                0 min
Cycle Time Optimization                      Fast Cool (default)

Oven
Temperature
Setpoint                                     On
(Initial)                                    70 °C
Hold Time                                    7 min
Post Run                                     70 °C
Program
#1 Rate                                      20 °C/min
#1 Value                                     150 °C
#1 Hold Time                                 5 min


Equilibration Time                           0.25 min
Max Temperature                              240 °C
Maximum Temperature Override                 Disabled
Slow Fan                                     Disabled

ALS
Injector
Syringe Size                                 10 μL
Injection Volume                             0.2 μL
Solvent A Washes (PreInj)                    3
Solvent A Washes (PostInj)                   3
Solvent A Volume                             4 μL
Solvent B Washes (PreInj)                    3
Solvent B Washes (PostInj)                   3
Solvent B Volume                             4 μL
Sample Washes                                3
Sample Wash Volume                           4 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                  6000 μL/min
Sample Wash Draw Speed                       300 μL/min
Sample Wash Dispense Speed                   6000 μL/min
Injection Dispense Speed                     6000 μL/min
Viscosity Delay                              0 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

SS Inlet He
Mode                                         Split
Heater                                       On    250 °C
Pressure                                     On    2.0699 psi
Total Flow                                   On    57 mL/min
Septum Purge Flow                            On    6 mL/min
Pre-Run Flow Test                            On
Pre-Run Flow Test Action on Failure          Abort
Gas Saver                                    Off
Split Ratio                                  50 :1
Split Flow                                   50 mL/min
Liner                                        A Liner has not been selected.

Column
Column #1
Flow
Setpoint                                     On
(Initial)                                    1 mL/min
Post Run                                     0.57353 mL/min

Column Information                           Agilent 123-9334UI-INT: US20400239
DB-BAC1 UI                                   
Temperature Range                            20 °C—270 °C (270 °C)
Dimensions                                   30 m x 320 μm x 1.8 μm
Column lock                                  Locked
In                                           SS Inlet He
Out                                          MSD 
(Initial)                                    70 °C
Pressure                                     2.0699 psi
Flow                                         1 mL/min
Average Velocity                             30.691 cm/sec
Holdup Time                                  1.6291 min
Control Mode                                 Constant Flow

Column Outlet Pressure                       0 psi

Agilent Intuvo 9000 GC Components
Guard Chip
Temperature
Setpoint                                     On
(Initial)                                    210 °C
Post Run                                     100 °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                  On




Valve 1
Type                                         Gas Sampling Valve
GSV Loop Volume                              1 mL
Load Time                                    0.5 min
Inject Time                                  0.5 min

Signals
Signal #1:  Test Plot
Description                                  Test Plot
Save                                         Off
Data Rate                                    50 Hz

Signal #2: 
Description                                  None

Signal #3: 
Description                                  None

Signal #4: 
Description                                  None




MS Information
-- -----------


General Information
------- -----------


Acquisition Mode         : SIM
Solvent Delay (minutes)  : 4.5
Tune file                : D:\MassHunter\GCMS\1\5977\ATUNE.U
EM Setting mode Gain     : 5.000000

Number of SIM Groups     : 2
Run Time (if MS only)    : 650 minutes 

[SIM Parameters]
Group 1               Group ID                  : toluen
Resolution                : 0
Group Start Time          : 4.5
Number of Ions            : 2
Ions
Dwell In Group            :(  Mass,  Dwell) (  Mass,  Dwell)  (  Mass,  Dwell) 
                           (  91.00,50  )  (  92.00,50  ) 
Group 2               Group ID                  : amyl alcohol
Resolution                : 0
Group Start Time          : 5.8
Number of Ions            : 2
Ions
Dwell In Group            :(  Mass,  Dwell) (  Mass,  Dwell)  (  Mass,  Dwell) 
                           (  55.00,50  )  (  70.00,50  ) 


[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: US1422L218
                        ---------------------------------

 Trace Ion Detection is OFF.

    34.593   :   EMISSION     
    70.007   :   ENERGY       
    31.712   :   REPELLER     
    90.331   :   IONFOCUS     
    17.627   :   ENTRANCE_LENS
  1121.040   :   EMVOLTS      
                              1388  : Actual EMV 
                               5.00   : GAIN FACTOR 
   358.000   :   AMUGAIN      
   123.938   :   AMUOFFSET    
     1.000   :   FILAMENT     
     0.000   :   DCPOLARITY   
    15.482   :   ENTLENSOFFSET
     0.000   :   Ion_Body     
     0.000   :   EXTLENS      
 -1040.000   :  MASSGAIN        
   -35.000   :  MASSOFFSET      

                        END OF TUNE PARAMETERS
                        ----------------------



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

Best Regards,

Standwi

Was this helpful?