Ghost Peaks -- HELP!

[Peter Apps]

One dud bottle, or even a whole dud batch from one supplier is not all that unlikely, but two duds of different grades from different suppliers ?? I would be VERY interested to know who the suppliers are.

What are you using as the wash solvent(s) on the autoinjector ?

Check also that there is no crud on the little plastic needle guide - though clean chromatograms with the old ACS hexane suggest that you rsystem is clean.



Peter

[JM]

mhof,
You have still not clarified whether you are using n-haxane or Hexane ?

check the label of old bottle and your new ones,

JM

[mhof]

The first chromatogram is hexane, the second is n-hexane. I finally got clean run using A.C.S./HPLC hexanes; the same product with different lot numbers gives drastically different results -- something must have changed with the supplier. I'm still waiting to hear back from them.

[mhof]

Fisher sent the following notice regarding the hexane:

We do not guarantee lot to lot consistency on our H302 (HPLC Grade) and
H334 (Spectranalyzed) for GC/MS applications. The GC/MS grade is beyond
scope of the 2 grades you provided. The highest grade of hexane that we
sell is the GC Resolve Grade, for organic residue analysis (H307-4).

The hexane produced industry-wide (Petroleum Industry) has changed the
n-hexane content from 85% to 60 to 65% and 95% respectively.

I knew that the product was not specifically formulated for GC work, but have used the same product for 5 years, and it has suited our needs perfectly.

I sent representative chromatograms to the other supplier from the GC grade hexane, and they are still deciding what to do.

Talk about bad luck! I had no idea that the standards for the hexane had changed... Same product code, same label, but a new chromatographic profile. Ouch.