Sensitivity loss on Trace 1310 coupled to QExactive-GC
Posted: Mon Jul 27, 2020 9:27 pm
System: Thermo 1310 Trace GC with PTV injector. Restek 2×120mm baffled Topaz liners w/o wool. Coupled to QExactive-MS system in +EI @ 43 eV, 80 mA. Agilent DB-1HT 15m×0.32mm×0.1µm @ 3.0 mL/min UHP He 5.0. Inlet pressure at injection is 14 psi (pulsed-splittless) for 2 min.
I've recently had a loss in sensitivity (about 2 orders of magnitude) for a couple brominated flame retardants in a PTV/GC-MS method I have been running for years.
I have a suite of chemicals (PCBs, perchloro-terphenyls, and PBDE-209 and PBDEthane-209) in my analysis. Most of the chlorinated analytes are still responding OK, however, the brominated species have dropped in response considerably. I used to be able to calibrate down to 0.4 ng/mL (1µL injections) now I can barely see them at 40 ng/mL.
Recently, after completely disassembling the PTV injector, I noticed quite a bit of color/contamination coming through the gas lines and the injector body on the PTV. I flushed them with MeCl2 and Acetone (about 1 L total) until I could not see anymore color. The color was yellowish like Pyrene and other PAHs. I've reinstalled the injector after cleaning and replace 1 m guard on my column. Column is brand new except for about 50 injections of standards and blanks during troubleshooting.
I am suspecting that since the gas lines and inlet body were visibly contaminated it is simply too active/contaminated still to provide adequate recovery of my analytes at low concentrations/mass.
Does anyone have any thoughts, guidances, suggestions, or experience on the Trace 1300 PTV systems?
EDIT: Solvent is Toluene and/or isooctane.
Thanks,
Ty
I've recently had a loss in sensitivity (about 2 orders of magnitude) for a couple brominated flame retardants in a PTV/GC-MS method I have been running for years.
I have a suite of chemicals (PCBs, perchloro-terphenyls, and PBDE-209 and PBDEthane-209) in my analysis. Most of the chlorinated analytes are still responding OK, however, the brominated species have dropped in response considerably. I used to be able to calibrate down to 0.4 ng/mL (1µL injections) now I can barely see them at 40 ng/mL.
Recently, after completely disassembling the PTV injector, I noticed quite a bit of color/contamination coming through the gas lines and the injector body on the PTV. I flushed them with MeCl2 and Acetone (about 1 L total) until I could not see anymore color. The color was yellowish like Pyrene and other PAHs. I've reinstalled the injector after cleaning and replace 1 m guard on my column. Column is brand new except for about 50 injections of standards and blanks during troubleshooting.
I am suspecting that since the gas lines and inlet body were visibly contaminated it is simply too active/contaminated still to provide adequate recovery of my analytes at low concentrations/mass.
Does anyone have any thoughts, guidances, suggestions, or experience on the Trace 1300 PTV systems?
EDIT: Solvent is Toluene and/or isooctane.
Thanks,
Ty