Discussion Category: GC-Single Quad/MSD
Instability of 5975C with reguards to DFTPP
First let me say that the mass spec has been thoroughly cleaned. I have tried dozens of times to retune and pass DFTPP for EPA method 525. First problem is that when tuning, the mass spec cannot achieve the set values for ions 131, 219, or 502. When shooting 5ng of DFTPP, the values I get for raw abundance and relative abundance changes from injection to injection with the primary ion failing being 68. I also see as the major ion for DFTPP 168 instead of 198. Agilent had someone come in yesterday to fix the problem and he had no idea what was going on. After trying all that he knew, he left with the mass spec still not operational. Can anyone tell me what is going on with the mass spec?
Reply byBill,
The first place I would start is to run a standard spectra autotune and see if it meets the Agilent criteria. Run the tune and compare it to these values:
Mass Assignments +/- 0.2 amu
Peak Widths 0.45 - 0.65 amu
Mass 69 Abundance >200,000 and <400,000\
<200 Total peaks in scan data
mass 69 is the base peak
mass 70/69 >0.5% and less than 1.6%
mass 219/69 >40% and less than 85%
mass 220/219 >3.2% and less than 5.4%
mass 502/69 >2.0% and less than 5%
mass 503/502 >7.9% and less than 12.3%
If the standard spectra tune can reliably meet these criteria the MS should be ok, if not there is a problem.
Let me know and we can move on from here
Dan
Dan Ste.Marie
RJ2 Instrument Services
Erie, PA
www.rj2.biz
Reply byBill,
The first place I would start is to run a standard spectra autotune and see if it meets the Agilent criteria. Run the tune and compare it to these values:
Mass Assignments +/- 0.2 amu
Peak Widths 0.45 - 0.65 amu
Mass 69 Abundance >200,000 and <400,000\
<200 Total peaks in scan data
mass 69 is the base peak
mass 70/69 >0.5% and less than 1.6%
mass 219/69 >40% and less than 85%
mass 220/219 >3.2% and less than 5.4%
mass 502/69 >2.0% and less than 5%
mass 503/502 >7.9% and less than 12.3%
If the standard spectra tune can reliably meet these criteria the MS should be ok, if not there is a problem.
Let me know and we can move on from here
Dan
Dan Ste.Marie
RJ2 Instrument Services
Erie, PA
www.rj2.biz
Reply byHi Dan,
I just run a tune and here is what I am seeing:
69/70 iso ratio: .98
219/220 iso ratio 4.03
502/503 iso ratio 11.27
scan found 166 peaks, base 69, abundance 573312
mass 69 Pw50 0.54
mass 219 Pw50 0.49
mass 502 Pw50 0.50
set abundance 131 45.0, actual 52.8
set abundance 219 55.0, actual 70.3
set abundance 414 2.0, actual 3.8
set abudance 502 2.0, actual 3.9
Reply byBill,
Based on these values it looks like the MS is able to tune appropriately, base abundance for 69 is high but i think you got that from the scan portion and not the profile data. The next question, is the MS stable you can determine by selecting generate report under the file menu in the diagnostics screen. Try generating a report, with the stune file loaded, every 20 or 30 minutes and see if the data is comparable from one report to the next. The data will not match exactly but should be close.
Dan
Dan Ste.Marie
RJ2 Instrument Services
Erie, PA
www.rj2.biz
Reply byOK, it appears that hydrogen will eventually cause problems in a 5975C. Reviewing my instrument logs, I see that I needed to replace liners at 3 times the rate when using helium. Also clipped column more often along with outher maintainance. I have switched back to helium and I am able to pass DFTPP parameters. I hjust finished a new curve for 525 along with a batch of samples I extracted 3 weeks ago. I am now running a 8270/625 calibration curve as I have over 100 samples backed up from extraction over the last 3 weeks. Bottom line, Agilent needs to head back to the lab with there instrument and fine tune issues associaded with hydrogen. I am more than happy to share my knowledge I've aquired over the last 9 months.
Reply byOK, it appears that hydrogen will eventually cause problems in a 5975C. Reviewing my instrument logs, I see that I needed to replace liners at 3 times the rate when using helium. Also clipped column more often along with outher maintainance. I have switched back to helium and I am able to pass DFTPP parameters. I hjust finished a new curve for 525 along with a batch of samples I extracted 3 weeks ago. I am now running a 8270/625 calibration curve as I have over 100 samples backed up from extraction over the last 3 weeks. Bottom line, Agilent needs to head back to the lab with there instrument and fine tune issues associaded with hydrogen. I am more than happy to share my knowledge I've aquired over the last 9 months.
Reply byOK, it appears that hydrogen will eventually cause problems in a 5975C. Reviewing my instrument logs, I see that I needed to replace liners at 3 times the rate when using helium. Also clipped column more often along with outher maintainance. I have switched back to helium and I am able to pass DFTPP parameters. I hjust finished a new curve for 525 along with a batch of samples I extracted 3 weeks ago. I am now running a 8270/625 calibration curve as I have over 100 samples backed up from extraction over the last 3 weeks. Bottom line, Agilent needs to head back to the lab with there instrument and fine tune issues associaded with hydrogen. I am more than happy to share my knowledge I've aquired over the last 9 months.