The principal changes needed when adopting LPGC-MS are presented below. They are also discussed in more detail in this technical article.
- When installing an LPGC column kit, make sure you are using a 0.8 mm ID Vespel/graphite ferrule for 0.53 mm ID columns or a 0.5 mm ID Vespel/graphite ferrule for 0.32 mm ID columns for the connection between the LPGC column kit and the MS. We recommend using a 60:40 Vespel/graphite ferrule if available. Note that the same ferrule used for a conventional 0.25 mm ID column is used on the restrictor end (inlet) of the LPGC column kit; only the MS end requires a different size ferrule.
- When configuring the LPGC column kit in your instrument’s software, you will only use the dimensions of the restrictor column portion of the kit because that narrow length of column predominately defines the kit’s overall restriction to carrier gas flow. When it comes to providing a stationary phase film thickness, you can use the thickness of the analytical column stationary phase, although this will have little impact on your instrument’s ability to correctly determine flow rates.
- You will need to update your method to increase the oven ramp rate and, likely, the carrier gas flow rate to achieve the greatest increases in analysis speed. Do not to exceed the maximum oven ramp rates for your GC oven or the maximum carrier gas flow rate for your mass spectrometer.
- We recommend that you tune your mass spectrometer under the same flow conditions that you will use for your LPGC method.
- Note: It is also likely that you will have to confirm/adjust retention time windows when a new LPGC column kit is installed. Even though elution orders will not change from kit to kit, absolute retention times may vary by tens of seconds (e.g., 10-20 sec).
For more information on installing and optimizing your LPGC-MS kit, check out our quick-start guide.
