paulsalverda
kristen.sensabaughSimply taking a method from a 7000 series system and attempting to run it under the same conditions on a 7010 series can cause multiple issues:
- Saturation - of the source, the quad, and the electron multiplier
- Isotope ratio problems
- Invalid quantitation results as a result of space charging effects (excessive saturation)
- Continual improper use could damage the system! Don't abuse your GCMS...
Here are the steps to figure out how much you can run on a 7010x system:
1. Run each new sample type in full scan mode (ie MS1Scan) with EM gain set to ~0.5.
If any of the peaks in the scan total ion chromatogram are flat topping (ie overloading the detector), including matrix peaks that you do not need to analyze, please do one or more combinations of the following:
a. Inject less until the chromatogram comes on scale.
b. Run the sample in split mode (use ultra-inert split liners) or even higher split ratios
c. Dilute the sample
d. Do further sample clean up
2. Make sure column flow rate is <1.5 mL/min into the MS while the filament is on
3. Always run constant flow mode methods. ALL GCMS sources work better under stable vacuum.
4. Make sure the solvent delay is long enough that all the solvent has eluted before the filament is turned on.
5. Make sure that there are no leaks. If you are using any CFT devices, Purged Ultimate Union, splitter, Deans Switch, there are more places leaks can occur.
6. Always make sure the quad temps are 150C or less. There is no reason to run the quads too hot. They really only need to be hot enough to be stable and eliminate water condensation. Anywhere between 106 and 150 will work up to the maximum source temperature.
7. Only certain applications need a source temperature >280C, so use 280C as a maximum temperature for the source when running samples.
The 7010 High Efficiency Source system is more sensitive than a 7000. This may require trade-offs in your methodology. Use that sensitivity to reduce the amount of sample injected and analyzed - that reduces the amount of normal user maintenance required. Less liners, gold seals, columns, filaments, and multipliers replaced and less source cleanings save you money and time!
