Carryover in Volatiles GC/MS

1 post / 0 new
Sumac
Sumac's picture
Carryover in Volatiles GC/MS

I'm having a problem with alternating low-recoveries/massive carryover (higher than the standard) in my 4552 Archon/4660 Eclipse P&T/6890GC/5973MSD system.  I can't run the water side (inoperable), but I can place water in the P&T sparge tube to pinpoint issues.

I've rinsed EVERYTHING in the soil pathway (transfer lines/P&T/Soil probe-new/valve/etc.)  I'm going to change transfer lines and pencil trap in back of Archon today.  I'm also going to check each part of the system today going backwards from the GC to pinpoint the problem.

The odd thing is, it's not typical carryover.  Certain compounds almost disappear and then reappear in rinses at VERY high concentrations.

2_CEVE has disappeared.  Ketones(2-Hexanone esp., and Cyclohexanone the worst)/Propionitrile/Acetates are the most noticeable problem.  These take up to 6-10 rinses to go away, and some never go away no matter how many rinses.  Then they'll be very low in a standard.

Any guidance would be greatly appreciated.