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- Posts: 2
- Joined: Mon Feb 19, 2018 5:14 pm
I am having an issue within our new MassHunter system, and am showing very low sensitivity with my lowest standards in my curve. My upper level peaks look great (highest level is 5000ng/mL, lowest is 10ng/mL), but my lowest peaks are hard to integrate as they are flat and have extremely low area responses. I am running PAHs, and here are some of my parameters:
Pulsed Splitless
Temp - 300C
Liner - Low Pressure Drop Liner with Glass Wool
EPP Ref Temp - 80C
EPP Initial Pressure - 11.5 psi
EPP Initial Hold - 0 min
EPP Ramp 1 - 98 psi/min
EPP Final Pressure 1 - 80 psi (constant flow mode)
EPP Pressure 1 Hold - 0.3 min
EPP Ramp 2 - -98 psi/min
EPP Final Pressure 2 - 11.5 psi
Carrier (Helium) - 40cm/sec
Carrier Flow - 1.2 mL/min
Time ON - 1.8 min
Split Flow - 40 mL/min
Oven Temp:
Initial Temp - 80C
Initial Time - 1.0 min
Ramp - 12C/min
Final Temp - 350
Hold Time - 3 min
Interface Temp - 300C
Source Temp - 250C
Quad Temp - 150
SIM mode
Relative EMV Voltage
4 min Solvent Delay
Column: DB-5MS 0.25mm x 30 meters x 0.25um
I was going to upload some pictures of the peaks, and maybe can if need be. Basically though, I am getting flat pancake peaks for my lower levels, but nice sharp peaks for my upper levels, and my responses for some of my compounds are tiny (example: area response = 29). Anyone know if there is a setting that is different between MassHunter and ChemStation that I am forgetting or missing possibly? MH is a new system for us, and am still trying to figure it all out. I have checked the connections between MS and injection port, and all look okay, plus ATune looked fine as well with everything passing and looking similar to tunes I had ran before we switched over to MH. I have ran MH with no problems for a few other methods I run (on different instruments though), but for my PAHs they just aren't quite working the same. We did just have the HED power supply replaced as well, and source was cleaned less than 6 months ago, and has not been ran on much since the MH install. Any help or ideas greatly appreciated! Thanks!