VOC issue ( strange SO2)

[Bigbear]

I've got SO2 in everything I purge. From direct injections through out my system it's coming from "up stream" of the water condenser
I've changed the sparge vessel and sample mount ( Tekmar Stratum) . I have also rinsed the Aquatek 70's sample path with MeOH and water.

I'm perplexed how a gas can persist in my system as well as how it got there. We do run some sulfur well water but it has never caused this issue before. I keep telling myself it couldn't have come from the 504 ( ~0.6 mg/ml thiosulfate) sample I ran.

[HPLC chemist]

Do you use sulfate or thiosulfate in your buffers or reagents? Under acidic conditions they can produce 'Sulfur Dioxide' gas.

[Bigbear]

Not usually. Our samples contain ascorbic acid and HCl. I only ran the 504 sample ( thiosulfate) as one channel of our ECD setup claimed 1,2,3-TCP. For "grins" I ran it on out VOC setup. Shoulda thought twice or more!!!!!!!!!!!

[James_Ball]

Not usually. Our samples contain ascorbic acid and HCl. I only ran the 504 sample ( thiosulfate) as one channel of our ECD setup claimed 1,2,3-TCP. For "grins" I ran it on out VOC setup. Shoulda thought twice or more!!!!!!!!!!!

I always ran into problems with it when I received Waste Water samples for EPA624 analysis because in the method it lists thisulfate as the chlorinating agent and HCl for the anti bacterial agent. They are actually supposed to be two separate vials but most people collect and preserve with both. Two drops of 1:1 HCl will work with the thiosulfate but two drops of concentrated will not, you get elemental sulfur dropping out and SO2 everywhere.

Did you receive any samples for THM only, because by EPA524.2 those can be collected with thiosulfate only, but some people also add the HCl like they would with ascorbic acid?

[Bigbear]

Our samples for VOC have AA and HCL, no thio in any VOC samples. The 504 sample I ran hat thio only, no acid.

[Bigbear]

Update, I got rid of the SO2 when I swapped out the water condenser on the Stratum, I also rinsed the tubing that connects the trap and condenser.