Persistent Carryover Contamination in Thermo TRACE 1600 GC –

[Nadee]

Hello,
We’re using a Thermo TRACE 1600 GC. recently have an issue with carryover contamination. After injecting six alkenone samples in a row, we ran a solvent (hexane) blank — but the same contamination peaks, including the alkenone peaks, still appeared. We think its sample carryover.

I understand it’s good practice to include solvent blanks between every 2–3 samples to minimize this issue. Here’s what we’ve done so far to troubleshoot:

1. Baked the column at 330°C for 15 minutes

2. Cleaned and replaced the syringe cleaning solvent vials and caps

3. Purged the column for 15 minutes

4. Conditioned the column for 15 minutes

5. Replaced the liner

Despite all this, the same contamination peaks persist. Our next step is to cut about 2 cm from both ends of the column.

This issue only started this week. last week’s sequence (which included solvent blanks) ran perfectly, and the solvent chromatograms were clean, without any contamination or alkenone peaks.

Has anyone experienced a similar problem? Any suggestions or insights on what else we could try to resolve this carryover issue?

Thank you for your time.

[uzman]

Did you try to change the syringe ; if you have an autoinjector ?
Dirty split trap may another source.