Agilent; 5975C/7890A GC-MSD leak problem

[prashant]

Hello Everybody!
We have a GC_MS from Agilent (5975C/7890A). I was satisfied with the working conditions of this instrument since a long-time (~3 years). From last few days it shows some problem. I have checked some tests,
1. Air/water leak test: It shows error divide by zero (it does not show any count for 69, 18 and 28)
2. Tune evaluation: gives error code: 222
3. Auto Tune: Gives error that either PFTBA is empty in the calibration vial (which is not the case) OR High Air Leak

I have doubt regarding the leak in the system especially around the PFTBA calibration vial.
Because, in the ideal mode the vacuum goes up to e-6. However, when PFTBA is injected it suddenly gives sharp decrease in vacuum, sometimes ~e-2 also. I also feel that PFTBA is not getting injected in the system, because I could not see any counts corresponding to the major ions (69, 219 and 502).
So, kindly give your suggestions.

Thanking you,

With regards,

Prashant

[MX304]

Was any maintenance done before seeing this issue such as a source or column change that required venting the system and opening the analyzer? If not, have you verified there is no break in the column? Error code 222 is a rather vague code. It can mean any number of things, the most common of which is low vacuum, or the instrument is in vent state. If you go into the parameters menu in tune and vacuum control, then do a scan, what does it show for the foreline pressure? If it still errors out in scan saying the calibration vial is empty, setting the PTFA calibrant valve to close, then scan again. Another thing to try would be purging the calibrant vial. If the solenoid valve is stuck closed you will get a more detailed error message when you attempt to purge it.

[prashant]

YES, a new column was replaced. But then one batch of samples (~12) were analyzed. Prior to the analysis I have checked the parameters and it was okay at that time. After a week, this problem occurred. Well as you (MX304) have suggested, I did manual tuning, with or without PFTBA i.e. in open and closed state, but it gives an error that "PARAMETER MASG VALUE OUT OF RANGE [-2048, 2048].
What should be the next positive step? Could anyone suggest?


With regards,


Prashant

[MX304]

but it gives an error that "PARAMETER MASG VALUE OUT OF RANGE [-2048, 2048].
What should be the next positive step? Could anyone suggest?


With regards,


Prashant

I'm sure you have already checked, but make sure all the wires to your source are still connected and connected in the correct place. In the past when I have seen that message it was usually either the blue or orange wire leading to the ion focus / entrance lens being lose, or connected backwards. I have even been able to get a good tune and a few samples run before it started to error out. Try ramping the lens and ion focus in manual tune. If you get a bad or low signal you may have a lose connection there.

[prashant]

Thanks MX304 for replying.
All the wires connected to source seems correctly placed as shown in the video provided by Agilent. But we haven't checked if its loose or tight as we have not opened chamber after your post.
However, we have done some tests....
As suggested by you, we tried ramping of ion focus and entrance lens...and results are...
For Ion Focus: Mass 69- Range (51380 to 246299); Mass 219 (33963 to157735); Mass 502- (2901 to 11429)
For Entrance lens: Mass 69- Range (233136 to 271226); Mass 219 (118421 to 165125); Mass 502- (9437 to 14401)

Moreover, we checked some electronics part and measured voltage at some test points....found EM monitor voltage = 0 and EM fault voltage =4.70 which indicates some fault..

Please advise...

[MX304]

Thanks MX304 for replying.
All the wires connected to source seems correctly placed as shown in the video provided by Agilent. But we haven't checked if its loose or tight as we have not opened chamber after your post.
However, we have done some tests....
As suggested by you, we tried ramping of ion focus and entrance lens...and results are...
For Ion Focus: Mass 69- Range (51380 to 246299); Mass 219 (33963 to157735); Mass 502- (2901 to 11429)
For Entrance lens: Mass 69- Range (233136 to 271226); Mass 219 (118421 to 165125); Mass 502- (9437 to 14401)

Moreover, we checked some electronics part and measured voltage at some test points....found EM monitor voltage = 0 and EM fault voltage =4.70 which indicates some fault..

Please advise...

I'm not familiar enough with the voltage test points to be much help with that. I assume if you were truely not getting any EM voltage that you wouldn't get any scan results, and wouldn't be able to read any ramp parameters. It's starting to sound more like a board or module failure. If you have another instrument of the same type, I would start by swapping the complete analyzer door assemblies between the two and see if the problem moves. If it does, then it's probably something side board related. If the problem doesn't move, them it's something in the lower electronics like a main board or the EM power supply.

[prashant]

Unfortunately we don't have other similar instrument.......nevertheless, is there a way to find out or pin-point a problem...I mean can we know that problem lies around source or EM itself or it is related to any electronic module....because our EM is 3-4 years old.......
Is there any way to be sure that certain part is OK so we can eliminate that part and narrow down the problem???

Thanks again........

[Don_Hilton]

Your description that the vacuum guage make the large change from 10e-6 to 10e-2 when you inject PFTBA is significant. I assume you are describing the valve to the PFTBA opening as being the injection. While a pressure pulse is to be expected, this is a bit much. And I am going to guess that the vacuum reading remains somewhere around 10e-2 while the valve is open? If so, the problem is likely to be either in the PFTBA valve or the ferrule holding the PFTBA has come loose or has been damaged. I have seen at least one type of instrument where overtigtening this connection would crush the ferrule and it begins to leak. I do not know what Agilent is using on the 5975.

Has any one put fingers on the PFTBA vial about the time thsi problem arose?

[prashant]

Thanks Don_hilton for replying....
It was going down to e-2 for 3-4 seconds and came back to e-5 level...however after replacing o-rings of valve and carrol it does not go upto e-2 level....it remains at 4.8 e-5 to 6-7 e-5 level and coming back to 4.8 e-5....

Can we point out something with some kind of tests?????

[Don_Hilton]

I am not sure about this remaining at only 5e-5. I've not worked with the 5975 - and it has been a long time since I've worked with a 5973, so someone with current experience needs to jump in.

What is 1) the pressure reading for the instrument with the PFTBA valve closed and 2) what is the reading immediately after the valve opens and whant is 3) the reading after the valve has been open for 15 seconds?

[bhuvfe]

Unfortunately we don't have other similar instrument.......nevertheless, is there a way to find out or pin-point a problem...I mean can we know that problem lies around source or EM itself or it is related to any electronic module....because our EM is 3-4 years old.......
Is there any way to be sure that certain part is OK so we can eliminate that part and narrow down the problem???

Thanks again........

Have you tried if a new EM solves your problem?

When you do a spectrum scan what do you see? Air, ptbfa or noise (posting what you see might help)?

If you reset to defaults or simply take a fresh version of autotune macro (file called atune.mac) and do an autotune what happens? Sometimes these macro files get corrupted... especially when you have several power failures.

Good luck.

[Don_Hilton]

First we be sure of the vacuum system - we know there was/is a problem there. And we know that if we run the instrument with insufficient vacuum, we damage the instrument. Once we are sure that we are operating at adequate vacuum, and then we turn on the ion source and detector.

[prashant]

Hello Dear All,
In continuation to my previous post, we have observed one more thing. And we think that this is the main problem. During "TUNE EVALUATION" the mass 69 (of PFTBA) is coming earlier at 66 amu, whereas the other masses, 219 and 502 are OK. Probably there is a shift in the Mass Calibration Axis. Could someone suggest how to approach to correct this problem?

With regards,

Prashant

[PeterB]

Make sure that your that the directory you're saving your tunes to, is that same as the directory that you're getting your tunes from. If you're using a old tune value (ie the tunes you're doing to evaluate your tuning check aren't the tune files that are currently being produced by the instrument).

It sounds obvious, but it's remarkably easy to mess up, because they're set in different places. If your instrument, after being tuned, is still seeing mass 69 as 66 then I'd think you'd have a serious hardward problem. Using corrupted or simply very old tune files could be the problem though...

[prashant]

Problem is fixed....and I am yet to belive it was 2 minute job....My quadrupole frequency needed to be adjusted....Actually I did that before but the "video of quadruple adjust frequency" leaded us to wrong values ....so it wasn't done....after setting it to correct value it sorted out.....