HP 5890 GC-FID

Question

Hello everyone,

This is my first post and I'm excited to have discussions for this thread.

I wanted to start off with a small introduction with some of my experience. I have 4 years of experience in operation, maintenance, method development on the following systems: Agilent GC 7890 triple quad, Waters Xevo TQS LC-MSMS, Agilent ICPMS 7700x and 7500, GBC AAS and Waters HPLC.

In my new position I have inherited an old HP 5890 GC-FID (older than I am). Fairly obvious that I will not have software control over conditions and measurements. (Hell, my ChemStation software shut-down program doesn't work).

I have been operating for 6 months now with not too much trouble and have been releasing test results of samples. I recently have been receiving an EPPA Shutdown Error. This is similar to other posts I have seen for various GC models. I was able to get off Injections prior to the error shutting down the system and once I began my sequence the alarm went away. Eventually, the time of alarm got worse and worse.

Long story short, I figured out that EPPA was not a random error code, but referencing the pressure of Inlet "A". So I did some injections and watched the pressure which after a while if it doesn't reach the set point will shut down the instrument. I noticed that someone had changed my carrier gas cylinder tank, so the inlet system/column was not receiving sufficient gas to operate (Fairly simple).

I increased the gas flow to slightly above 50psi with the regulator and the alarm went away. The next day, I came into run my system check and noticed an extreme drop in signal (both analyte and baseline). I have lost my higher level standards signal (almost looking like a ******* beers law past 1). Additionally, my resolution is ****. I have multiple peaks forming one full peak at higher concentrations.

My hypothesis and plan moving forward: I assume the poor resolution is due to the inlet septa. So I'm going to replace the septa and liner. Then take some measurements of column flow/FID gas flows (hydrogen/air). To be honest, it wouldn't surprise me if the Jet needed replacement (I think the igniter isn't responding well either). My guess is that this instrument was neglected for years.

Anyways, pleasure meeting you all. Sorry for taking so long to meetup. (I will post or PM anyone who cares to see pics)

-holtsy907

james_jenkins · Accepted Answer

Hi holtsy907, I have updated the tags on your post for better visibility. I am familiar with the 5890 so I guess a little older than you . The EPPA pressure shut down is indeed the epc unable to maintain pressure. With the early version of EPC this was the displayed error when there were pressure/ leak / flow problems. The 5890 had several options for inlet pressure, based on the description above, I would say that your GC does not have the internal pressure regulator option. When you increased the tank pressure, you would have increased the flow on the mass flow controller (fixed restrictor) and raised the split ratio (assuming split/spltless from your description) thus decreasing response. On the front of the GC there is a total flow/ split vent that is effected by pressure changes on the gas line. You may be able to go back to your old pressure and adjust the total flow so that you have around 20ml/min. You have to measure this flow out the port using a bubble meter or electronic flow meter. The split/splitless inlet is designed around a flow of at least 20ml/min from that port for proper operation. If you could post some pictures of the GC I would be able to better identify your configuration. Regards James