Chromatography Forum

I have inherited an HP 5890 w/split splitless no EPC, FID. With a restek Stabiliwax 30m, 1micron film,
0.53mm ID column. I don't think it has been used since purchased many years ago.

First time working with split/splitless inlet. Not exactly sure what I am doing. Method requires 2mL/min carrier gas, 100mL split on a 30m 0.25mm ID column with 0.1-0.25 micron film thickness.

I have been testing at 2-4mL/min on the column, 100 mL off the split vent. The purge vent is a mystery to me, it looks plugged, but I can get flow out of it when I turn the purge inlet valve ON. Don't know how much flow I am supposed to be getting of this vent or if the valve should even be open? I have been running with it OFF. When I turn the valve ON the flow through the column goes up 5mL/min?

Anyway have been injecting toluene solvent blank and 100mg FAME dissolved in 10mL toluene as the method requires. All i get is one huge tailing solvent peak and no ester peaks. I imagine I am either getting too much sample on the column or I am losing sample on the inlet and not getting it on the column. The liner is straight tapered no wool. There is a new o-ring on it, but the liner has some small chips on the ground glass upper surface. I have the column seated 1-2 mm above the taper of the liner. I have about a half meter of 0.53m guard column connected with a glass press tight connection (came with another phenomenex column). I have checked all column connections/FID jet. One last thing is the "gold" seal at the bottom of the inlet, this one isn't gold but blue oxidized and sits on a metal washer.

Any suggestions or help would be greatly appreciated. Thanks.

Purge valve should be open, should flow up to 3 ml/minute. Set your inlet pressure with that control, and use the total flow to control how many ml/minute comes out the split vent.

Make sure your inlet temp is on, and at least 250C. I'd start with higher concentrations of fatty acid methyl esters to make sure I see those, first.

If you don't have standards at higher concentrations, make some from a bar of plain old soap, mix with methanol containing a little sulfuric acid or BF3, heat a few minutes, add water and NaCl extract into a little hexane. Blow off the hexane to get FAME, or just inject hexane. You'll get primarily C8 to C18 even chain FAMEs from the soap, with some oleic and linoleic.

The blue seal is a silico-steel one, OK if clean. Sounds like you need a new split liner, and I would use split mode not splitless.

Tried some runs with purge vent at 3mL/min, column at 3mL/min, and inlet vent at 100mL/min. Even more Delayed retention time of solvent and seeing signal spikes that suggest a leak.

Isn't running with the split vent open running in split mode? Does the liner dictate if it is split or splitless mode?

I only have a graphite ferrule on the column nut is there supposed to be a second ferrule underneath the silico steel seal?

Thanks,

azbiodiesel,

You should get flow out the split vent whether the valve is on or off on a 5890. (It is one of the the things that makes it so challenging to troubleshoot.) So, the fact that you only get it with it on is indicative of a problem with either the line from the inlet or the valve. You should leave Purge A (or B) ON all of the time. This means the power to the splitter valve is off (no power) which is the proper idle state and it means you are leaving the system in split mode. (I've always struggled with the Varian versus HP/Agilent nomenclatures but have finally got it sorted out......)

First thing for you to get to is split flow with the Purge A On and Purge A off. Until then, your inlet is not correct.

Best regards,

AICMM