Leco Pegasus III, What is this and how to clean it?

[Don_Hilton]

Do not flood the mass spec with argon. Argon has been implicated in detector failures. One can get a discharge in argon at very low pressures and my personal suspicion is that the argon ay slowly diffuse out of the microchannel plates slowly enough that you can get an arc and detector damage even though you have a good reacuum reading for the system.

The filament current will drop at the end of the standby time, but the ion sorce body heaters are still active. These you want to have turned on all the time. A four way valve after the GC column and before the mass spec would have a number of issues. Valves leak. It it is in the oven the temperature cycle causes expansion and shrinking. Mechanical deformation will cause valves to leak (more). So with a valve after the column, expect mixing in the volume inside the valve (peak shape degredation), increased air in the mass spec from leaks, and maintanance because of leaks. This is not to say that you can't to this. I have seen a GCxGC application or two which used mechanical valves. The one I have in mind was not because valves are so great, but rather that cryogenic modulation at the location was not feasable. Take a look at the solutions that allow you to change GC columns without venting the mass spec. None has a mechancial valve in the path between the GC column and the mass spec.

With the number of MS installations I have seen, it does seem to be common practice to keep flow through the GC and into the mass spec. A mL or so of He into a turbo pump is not an issue for the turbopump. If you look at curent draw and operating temperature, you are well within the range where the pump operates comfortably.

[James_Ball]

I would agree on maintaining the Helium flow when not in use. We have several systems with turbo pumps(all Agilent) and those run 24/7/365 with a constant 0.5-1.0 ml/min flow of helium and I haven't had to replace a turbo on over 10 years. Stopping and starting turbo pumps puts much more wear on them than a slow flow of helium will. If you want to help keep the system clean you could use a standby flow of hydrogen if you feel comfortable using it. I know the one GCMS I had setup with hydrogen was much cleaner than normal when I switched it back for helium use after a few months.

[steverb]

Fair enough. I will keep 0.5-1 ml/min Helium flow for now and later after setting up our little hydrogen generator system I will use hydrogen.

Still don't know which gas is better for long term shut down condition (6 month for example) for not causing any damage to the detector. I used to flush the chamber with Argon but Don suggested N2 is better. Filling the chamber with N2 and leave it for let say whatever month I need is the verdict.

Don suggestion about using no vent column changer adapter is very good. I will try to install one of those as soon as possible.

So far haven't find anyway of collecting data from FID detector using Chromatof. Is this possible? Who knows!.

I have CombiPal auto sampler, Optic 3 high performance injector, DTD and 6890N agilent GC connected to this Leco Pegasus III instrument. I haven't worked with these peripherals before. There are a lot of parameters involved and has to do a lot of settings and configurations. I am not sure if this is possible but If anyone is using this setup at the moment I am interested to use his/her setups (files) for these instrument to get started quicker and easier (to load them into my instrument).

Also will appreciate if anyone using these peripherals to explain step by step how these peripherals should be integrated with pegasus III in order to get the aquisition job started and finished successfully. When I define a task in Chromatof and start data acquisition nothing happening. I guess it is waiting for GC to get ready. I have checked all connection and they are OK. I am using com1-com5 serial ports for connecting everything. Autosampler and GC has an opting inside Chromatof to set the comunication port but nothing for Optic 3. There is a connection between Optic 3 and GC instead as manual says. I guess Optic 3 takes order from GC. It can be set in slave or master mode if it works with GC but for Pegasus III I don't know which mode should be set in the settings?

[Don_Hilton]

The combipal autosampler and 6890 configured with a Pegasus is common. For the GC, you need a serial connection and to have the speeds set to matching values in the instrument and the com port. For the CombiPal, you need to tell CHromaTOF hat the autosamper is the CTS rail type and again make sure both devices match on serial communication speed. I believe that reccomendations for speed are the the manual (avaialble thought help in ChromaTOF). I have seen an OPTIC system used - it has been a number of years ago. It seems to me that that system was moved and reconfigured later. My impressin was that the insterface was sucessfully integrated into the system. From outside the GC (to external software), the inlet looked pretty much like a PTV inlet. Inless there was a timing signal output, all the magic of the inlet was internal to the GC (and parameters had to be set outside the ChromaTOF software.)

The setup is fairly straightforward (unless there is something I totally don't remember with the OPTIC), but many details. It is an issue of time as each wire is connected and the communication checked.

On using a no-vent with the Pegasus: I don't know if this has been done. As I have looked at sales literaure, it looks like these come with a capillary ready for installation in a specific instrument's transfer line. The transfer line length is important and you need a capillary to match the LECO transfer line so the end of the capillary protrudes the correct distance.

[walshbig]

I have encountered a strange problem. I have established communication between Combi PAL and Cycle Composer (Ver 1.5.2). Cycle Composer reads Combi PAl configuration with no problem which show communication is OK. When I choose "Single Step Gc Injection" from Method Editor window and click "RUN" it asks for missing tray. After filling missing tray in the table I click Ok but no matter how long I wait nothing happens. I monitored serial port trafic and saw no command goes to Combi PAL at this stage. When I click reset PAL I see reset command is going into PAL but for some reason other command not going to PAL.

Single step GC injection uses "GC-Inj" macro. I have attached this macro listing below. I noticed two lines with "wait" command. I comment these lines but still nothing happened when I clicked "RUN" from method editor window. I was expecting Combi PAL fill Syringe after washing step and then inject it into the defined port but nothing happens. Anyone had the same experience? How this might be happening and how to diagnose and solve it?

GC-Inj Macro listing:


//COMPLETE CYCLE
//************************
//Duplication of PAL's local GC injection cycle.
//Tray Name, Sample Number and Sample
//Volume are taken from the sample list.
Air Volume (µl);0;0;Syr.Max Volume
Pre Clean with Solvent 1 ();0;0;99
Pre Clean with Solvent 2 ();0;0;99
Pre Clean with Sample ();0;0;99
Filling Volume (µl);0;0;SYR.Max Volume
Filling Speed (µl/s);SYR.Fill Speed;SYR.Min Speed;SYR.Max Speed
Filling Strokes ();5;0;99
Pullup Delay (ms);SYR.Pullup Del;0;10000
Inject to;INJECTOR;
Injection Speed (µl/s);SYR.Inject Speed;SYR.Min Speed;SYR.Max Speed
Pre Inject Delay (ms);500;0;99000
Post Inject Delay (ms);500;0;99000
Post Clean with Solvent 1 ();1;0;99
Post Clean with Solvent 2 ();1;0;99
WAIT_FOR_DS()
WAIT_SYNC_SIG(Start,)
CLEAN_SYR(Wash1,Pre Clean with Solvent 1,,,,,,,)
CLEAN_SYR(Wash2,Pre Clean with Solvent 2,,,,,,,)
REPEAT(Pre Clean with Sample,)
GET_SAMPLE(SL.tray,SL.index,SL.volume,Air Volume,,Filling Volume,Filling Speed,Pullup Delay,,0,Off,,,)
PUT_SAMPLE(Waste,1,,,,,)
END()
GET_SAMPLE(SL.tray,SL.index,SL.volume,Air Volume,,Filling Volume,Filling Speed,Pullup Delay,,Filling Strokes,Off,,,)
INJ_SAMPLE(Inject to,Inject,Injected,,,Pre Inject Delay,Injection Speed,Post Inject Delay,1,)
CLEAN_SYR(Wash1,Post Clean with Solvent 1,,,,,,,)
CLEAN_SYR(Wash2,Post Clean with Solvent 2,,,,,,,)

[Don_Hilton]

I would suggest start a thread under GC on this one. Teh Combi-Pal is widely used and I suspect that few beyond those of us who are Pegasus users are working our way to the bottom of this thread.

But before you go there...

The easy way to run your rail is to let ChromaTOF drive it and leave cycle composer inactive. And if you have the autosampler set up in ChromaTOF and in cycle composer, you have a conflict as to which program owns the IO port. If you use cycle composer, you have to tell ChromaTOF that you are running manual injections and then let ChromaTOF and Cycle composer run. The trick is tha you have to be sure that the method cycle time for cycle composer is just a bit longer than the GC/MS cycle time so that ChromaTOF will be looking for the start signal for the next sample in time. If termperatures are not quite equilbrated and cycle composer makes the next injection - ChromaTOF will not have detected instrument ready - and will not be ready for start. You have to build parallel sample tables in cycle composer and in ChromaTOF.

[walshbig]

I don't use both chromataf and cycle composer at the same time. I am aware of conflict. I tried chromatof too. I defined a task in chromatof. There were some hardware problem reported by chromatof because of wrong communication parameters and non defined objects first but after fixing these problems now chromatof says "active" and stays there no mater how long I wait. Nothing in log too This is what puzzling me. Both softwares fails which shows something fishy is going on. Tried to log serial trafic between PAL and chromatof but chromatof hangs when I run serial monitoring software at the same time.

[walshbig]

Problem solved. It was because of the "pol" file of optic3 was uploaded to PAL previously and it was waiting for commands from Optic3 I guess. After uploading PAL original firmware it start responding nicely to both Chromatof and Cycle Composer.

[walshbig]

Everything is ok now and I got sample analyzed and search in the NIST library finished with excact results but I had to press "Start" in GC manually because in Chromatof it went to "Gas Ghromatograph:state=ready and staus=pre-run" after sample injection finished and stopped there no matter how long I waited. Finally I have to push "start" on GC manually for data collection in Chromatof to start. This is not good when I have a lot of samples and can't be there to push start after every sample. There should be something I am missing here. What have I done wrong for GC not going to run state automatically after sample injection finished?

[Don_Hilton]

It looks like the Sampler is not connected to start the GC. It is the autosamper's "job" to push the start button on the GC. There needs to be a connection from the CombiPAL to the start/ready signals on the back of the GC.

[walshbig]

Thanks Don. You are a great help as usual.