Chromatography Forum

Hi

Please help! I'm my lab we use analytical grade reagent IPA as our blanks. We have noticed that there are several peaks in the blank. It's getting very confusing with identifying which peaks are real and which are in the blank. The blank peaks are appearing on five different GCs which indicates to me it must be the solvent.
1. Has anyone else had issues with solvents seeming to be contaminated.
2. Does anyone have any idea what we could be doing wrong

Do the peaks go away if you open a new bottle of solvent?

Do you use a fresh autosampler vial each day?

Have you checked to make sure there are no septa fragments in the GC inlet or tip of the column?

Also, you say blanks and the blank. Is it one vial or multiple? Has the cap and septum been changed?
As James asked, is it just the one bottle of solvent? Is it just one lot # of solvent? And finally, what if you change to a different solvent?

I'd contact the vendor. And purchase some IPA from 2 other sources, to try.

In the meantime, I'd inject some methanol and even ethanol denatured with just 5% methanol/5% IPA to see if such peaks disappear. As stated, first thing is to determine whether the peaks are present in that existing lot of IPA.

I remember in the early 1980s getting some packs of septa from HP, and they all leaked after a few injections. I called HP, and sent some back for testing, and they confirmed a bad batch of resin had been used, and confirmed poor quality and leakage.

Do the peaks go away if you open a new bottle of solvent?

Do you use a fresh autosampler vial each day?

Have you checked to make sure there are no septa fragments in the GC inlet or tip of the column?

We have used fresh Blanks. If it was due to GC inlet or column. It would be the same on all five gcs

Also, you say blanks and the blank. Is it one vial or multiple? Has the cap and septum been changed?
As James asked, is it just the one bottle of solvent? Is it just one lot # of solvent? And finally, what if you change to a different solvent?

It seems to be the case in two bottles of the iPA and now they are appearing in the IPA from a separate drum. They are not present in acetone

From recent experience (https://www.chromforum.org/viewtopic.php?f=3&t=118014), I think that is well worth trying a run without a septum on the sample vial (using fresh IPA) just to completely eliminate the vials as a potential source. I think from what you've said (i.e. testing on 5 GCs), the inlet septa are eliminated. Do you have access to a GC-MS? Would be nice to know what these peaks actually are...

As an aside what types of vial and septa are you using?

From recent experience (https://www.chromforum.org/viewtopic.php?f=3&t=118014), I think that is well worth trying a run without a septum on the sample vial (using fresh IPA) just to completely eliminate the vials as a potential source. I think from what you've said (i.e. testing on 5 GCs), the inlet septa are eliminated. Do you have access to a GC-MS? Would be nice to know what these peaks actually are...

As an aside what types of vial and septa are you using?

Auto sampler vials glass with snap tops for samples.

Not sure on septa type. They look pretty standard

From recent experience (https://www.chromforum.org/viewtopic.php?f=3&t=118014), I think that is well worth trying a run without a septum on the sample vial (using fresh IPA) just to completely eliminate the vials as a potential source. I think from what you've said (i.e. testing on 5 GCs), the inlet septa are eliminated. Do you have access to a GC-MS? Would be nice to know what these peaks actually are...

As an aside what types of vial and septa are you using?

Auto sampler vials glass with snap tops for samples.

Not sure on septa type. They look pretty standard