This Information Applies To: All Agilent 5977 GC/MSD systems working in EI mode
You can evaluate the 5977 MSD tune performance by reviewing the autotune report. Follow the steps in this article to review MSD tune performance.
Steps to follow:
1. Obtain the hardcopy tune report or open the PDF tune report file in the path X/MassHunter/GCMS/1/5977/PDF (see Figure 1).
Figure 1. PDF tune file in X/MassHuner/GCMS/1/5977/PDF
2. The mass peak profiles for the tune masses (m/z 69, 219 and 502) are shown in Figure 2.
The mass peak profiles should be smooth, symmetrical and even in width, the mass peak profiles should not have visible noise, splits, or precursors visible. Figure 2 shows a normal example.
3. The table in Figure 3 displays the Mass Assignment (Actual m/z), Mass Abundance (Abund), Mass Relative Abundance (Rel Abund), and Mass Peak Width at 50% Height (PW50) for each of the three tune mass profiles.
The Actual m/z (mass assignments) for the tune masses should be within +/- 0.2 m/z of the actual mass at m/z 69.0, 219.0, and 502.0.
The Abund (Mass Abundance) for the highest abundance mass (m/z 69) should be between 450,000 and 550,000 counts if the target value is 500,000 counts. The abundances will change based on the target values.
The Rel Abund (Relative Mass Abundance to the Base Peak) should be >40% for m/z 219 and >2% for m/z 502.
The PW50 (Mass Peak Width at 50% Height) of all three tune masses should be 0.60 +/- 0.05 m/z if the target width is set to 0.60.
4. The MS Parameters table (see Figure 4) shows the parameter values set by the tune. These parameters are automatically saved in the tune file when the tuning is complete.
Target Mass Assignment (Target m/z).
Measured Mass Assignment (Actual m/z ) - should be within +/- 0.1 m/z of 69.0, 219.0, and 502.0.
Mass Abundance (Abund) – m/z 69 will have the highest abundance and should be between 450,000 and 550,000 counts if the target value is 500,000 counts. The abundances will change based on the target values.
Relative Mass Abundance (Rel Abund) - should be >40% for m/z 219 and >2% for m/z 502.
Isotope Measured Mass (Iso m/z ) - should be within +/- 0.1 m/z of 70.0, 220.0, and 503.0.
Isotope Abundance (Iso Abund) – should all be > 1000 counts.
Isotope Ratio (Iso Ratio) – should be close to the theoretical values (m/z 70 at 1.08%, m/z 220 at 4.32% and m/z 503 at 10.09%). As a quick check +/- 20% of the theoretical value is a good estimate, but the exact limits are shown in the tune evaluation report (See Figure 10)
7. Figure 7 displays the Air/Water (background of H2O, N2, O2, and CO2).
Values are Relative % abundance to m/z 69 abundance .
Acceptable values for tune evaluation are:
H2O: < 20%, N2: < 10%
For systems that have been under vacuum and at default operating temperature for at least 2 hours (Ion Source at 230℃ and Quadrupole at 150℃), typical values are:
H2O: < 20%, N2: < 5%, O2:< 1.5% (values may be different depending on the specific instrument conditions).
For systems that have been under vacuum and at default operating temperature for > 24 hours (Ion Source at 230℃ and Quadrupole at 150℃) there should be lower levels of H2O, typically < 5%.
The Air/Water Check is performed as part of the Tune Report after the MSD tuning processes.
If you need to quickly check for air leaks without having to run a full autotune, select Tune > Air and Water Check from the Tune and Vacuum Control View.
Note: If the MS hasn’t had the Calibration Valve opened from previous tuning or air/water check within the last hour, there may be a higher than normal air background. If unsure, repeat the air/water check several times until obtaining consistent values. The Air / Water check in the autotune report is performed at the end of the tuning process and the calibration valve will have typically been open for at least 3 minutes.
|Note: A sudden stepwise increase in the Gain Factor may be an indication of other possible issues (e.g. PFTBA calibrant has run out, vacuum pressure too high, air leak, too high column flow, aged / used filament). It will typically be associated with a sudden stepwise increase in the EM volts. Review several previous Autotune Reports (atune.u) to determine if the Gain Factor has been progressively increasing or has had a sudden stepwise increase.|