low level rl's for naphthalene using purge and trap

[chloesabrina]

Any luck with running naphthalene meeting a RL of 0.5ppb? I am going to try a larger volume purge and see what I can do, but just curious.

Agilent 6890
Encon purge and trap
Archon autosampler

Will be trying on the soil side first.

[Steve Reimer]

I can get enough response to see 0.5ppb with no problem if I am only looking for the 128 peak. The problem is that I get nasty samples and naphthalene is very persistent. With my system (6890/5975 OI4660 - Archon) a larger purge wouldn't be as helpful as careful screening.

The response is usually quadratic at low levels.

[chloesabrina]

I have the same problem with the samples - unfortunately even though some of these samples have to be diluted for naphthalene the client still wants a RL of 0.5ppb without running it by EPA8270. I ran a 10ml purge last night with an ical only going to 25ppb so I'm hoping to achieve the goal.

[Yama001]

I'll concur with Steve - detecting naphthalene at 0.5 ug/L is doable - not detecting it in clean samples is the problem.

[chloesabrina]

Great sounds good, thanks. These are definitely not clean

[Bigbear]

Works for me. Do 524 see down to 0.5 ppb. purge 25ml.

[James_Ball]

I have the same setup and can see 0.5ppb with little problems. We purge 5ml sample.

What type of trap are you using?
What is your split ratio?
What GC column?



I use a custom packed trap with Carboseive SIII, Carboxen1000 and CarbopackB. Similar to the VoCarb3000. For Naphthalene use a Vocarb3000 or Vocarb4000 or possibly the BTEX trap. The biggest problem I have so far is the carryover of Naphthalene, but if you run the transfer lines at 130c and use the 5ml sparge tube and rinse with 8ml DI after a 5ml sparge it helps.

Been running purge and trap for twenty years and still there isn't a day I don't see some new problem with it. Just keeps things exciting

[chloesabrina]

Thanks James_Ball

I use the Voacarb 3000, DB624 column with a 1:50 split. I was actually able to see it with the 5ml purge and get a decent result +-30% after chopping off most of my upper points and just leaving 6 points with a quadratic curve.

I will have a really hard time of it if some of site gets cleaned up since the carryover will be awful. So far I have never reported anything below 5ppb for them.

I have only been running purge and trap for ~8 years now, but it is my favorite since it never gets old.