I am having trouble separating methyl methacrylate (MMA) from another peak. The interfering compound, appearing in the front, is identified by library as 3,3-dimethyl-2-butanone and it is inherent to the sample. MMA appears as the split/tailing peak. Both compounds have a boiling point around 100 C. Identification by mass spectrum is also challenging because both compounds share m/z values 41, 69, 85, and 100. However the interferent is often identified by m/z 57.1.
How can I separate these two peaks? If I change the detector settings to start looking at m/z 60 (essentially excluding the 57.1) will that improve anything?
INSTRUMENT CONTROL PARAMETERS: 1 ----------------------------------- Wed Jan 17 15:49:45 2024 Control Information ------- ----------- Sample Inlet : GC Injection Source : External Device Mass Spectrometer : Enabled Injection Location: Front No Sample Prep method has been assigned to this method. GC GC Summary Run Time 22.133 min Post Run Time 0 min Oven Temperature Setpoint On (Initial) 32 °C Hold Time 7 min Post Run 70 °C Program #1 Rate 10 °C/min #1 Value 70 °C #1 Hold Time 0 min #2 Rate 30 °C/min #2 Value 320 °C #2 Hold Time 3 min Equilibration Time 0.25 min Max Temperature 320 °C Maximum Temperature Override Disabled Slow Fan Disabled Front SS Inlet He Excluded from Readiness ***Excluded from Affecting GC's Readiness State*** Mode Split Heater On 250 °C Pressure On 17.909 psi Total Flow On 22.02 mL/min Septum Purge Flow On 3 mL/min Pre-Run Flow Test Off Gas Saver On 20 After 3 min mL/min Split Ratio 10 :1 Split Flow 17.291 mL/min Liner Agilent 5190-2293: 900 μL (Splitless, single taper, wool, Ultra ) Back PTV Inlet He Mode Sleep Pressure Off Septum Purge Flow Off Pre-Run Flow Test Off Liner Agilent G1544-80730: 675 μL (Direct connect, single taper, bottom ) Column Column #1 Flow Setpoint On (Initial) 1.7291 mL/min Post Run 0.57353 mL/min Column Information Agilent Restek-Rxi5SilMS Temperature Range -60 °C—350 °C (350 °C) Dimensions 30 m x 250 μm x 0.25 μm Column lock Unlocked In Front SS Inlet He Out PSD 2 (Initial) 32 °C Pressure 17.909 psi Flow 1.7291 mL/min Average Velocity 34.759 cm/sec Holdup Time 1.4385 min Control Mode Constant Flow Column #2 Pressure Setpoint On (Initial) 2 psi Post Run 10 psi Temperature Range -1 °C—325 °C (325 °C) Dimensions 5 m x 200 μm x 0 μm Column lock Unlocked In PSD 2 He Out MSD (Initial) 32 °C Pressure 2 psi Flow 1.5224 mL/min Average Velocity 109.14 cm/sec Holdup Time 0.076352 min Control Mode Constant Pressure Column Outlet Pressure 0 psi Front Detector FID Excluded from Readiness ***Excluded from Affecting GC's Readiness State*** Makeup He Heater On 300 °C H2 Flow Off Air Flow Off Makeup Flow Off Carrier Gas Flow Correction Constant Makeup and Fuel Flow Flame Off Detector Evaluation Perform Detector Evaluation Test Off Signal Selected No Signal Selected Checkout Sample None MSD Transfer Line Temperature Setpoint On (Initial) 320 °C Aux EPC 1,2,3 Aux EPC 1 N2 Pressure Setpoint Off (Initial) 10 psi Post Run 10 psi Excluded from Readiness ***Excluded from Affecting GC's Readiness State*** Aux EPC 2 N2 Pressure Setpoint Off (Initial) 10 psi Post Run 10 psi Excluded from Readiness ***Excluded from Affecting GC's Readiness State*** Aux EPC 3 N2 Pressure Setpoint Off (Initial) 10 psi Post Run 10 psi Excluded from Readiness ***Excluded from Affecting GC's Readiness State*** PSD 2 Excluded from Readiness ***Excluded from Affecting GC's Readiness State*** PSD Purge On 0 mL/min PSD 2 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 GERSTEL MAESTRO SYSTEM SETTINGS Maestro Runtime : 22.13 min GC Cool Down Time : 5.00 min Cryo Timeout : 15.00 min GERSTEL CIS CIS : not used - use these parameters if it becomes 'used' CRYO COOLING Cryo Cooling : used TEMPERATURE PROGRAM Heater Mode : Standard Liner Type : 013882-010-00 glass liner CIS4, baffled, non deactivated Liner Max Temperature : 400 'C Initial Temperature : -10 'C Equilibration Time : 0.50 min Initial Time : 0.50 min Ramp 1 Rate : 12.00 'C/s End Temp : 325 'C Hold Time : 5.00 min Ramp 2 Rate : 0.0 'C/s Low Split : not used GERSTEL MPS PREP Sample Prep : used PREP ACTION LIST Action Method/Value Source Destination ============= =================== =================== =================== GERSTEL MPS Liquid Injection Syringe : 10ul 65mm USM SAMPLE PARAMETERS Sandwich : not used Inj. Volume : 1.0 uL Air Volume below : 0.0 uL Inj. Speed : 50.00 uL/s Fill Volume : 5.0 uL Fill Strokes : 5 Fill Speed : 2.00 uL/s Viscositiy Delay : 0 s Eject Speed : 50.00 uL/s Pre Inj. Delay : 0 s Post Inj. Delay : 0 s Inj. Penetration : 40.00 mm Sample Tray Type : VT54/2-CVM Bottom Sense : used Fast Injection : used CLEANING PARAMETERS Preclean Sample : 2 Wash Station 1 : Pos1@Standard Wash 1 Preclean Solv.1 : 2 Postclean Solv.1 : 6 Clean Volume Solv.1 : 90 % Fill Speed Solv.1 : 5.00 uL/s Viscosity Delay Solv.1 : 0 s Eject Speed Solv.1 : 50.00 uL/s Information Solv.1 : Hexane Wash Station 2 : Pos2@Standard Wash 1 Preclean Solv.2 : 0 Postclean Solv.2 : 0 Clean Volume Solv.2 : 70 % Fill Speed Solv.2 : 5.00 uL/s Viscosity Delay Solv.2 : 0 s Eject Speed Solv.2 : 50.00 uL/s MS Information -- ----------- General Information ------- ----------- Acquisition Mode : Scan Solvent Delay (minutes) : 3.3 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) : 23.67 minutes [Scan Parameters] Start Time : 3.3 Low Mass : 40 High Mass : 300 Threshold : 300 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: US2018M021 --------------------------------- Trace Ion Detection is OFF. 34.593 : EMISSION 70.007 : ENERGY 3.192 : REPELLER 89.822 : IONFOCUS 22.672 : ENTRANCE_LENS 1665.995 : EMVOLTS 2022.2 : Actual EMV 5.00 : GAIN FACTOR 1873.000 : AMUGAIN 132.813 : AMUOFFSET 1.000 : FILAMENT 0.000 : DCPOLARITY 6.828 : ENTLENSOFFSET 9.002 : Ion_Body 3.506 : EXTLENS -255.000 : MASSGAIN -32.000 : MASSOFFSET END OF TUNE PARAMETERS ---------------------- END OF INSTRUMENT CONTROL PARAMETERS ------------------------------------