PCB's in Caulking

[MarkRob]

Hi there,

this post is related to one from earlier this week.

Can anyone tell me what approach they use to PCB identification and quantification (using ECD) I have analyzed samples which have peaks similar to, but not exact in shape to those of our reference aroclors.

On paper, it doesn't look like an exact match, but the chromatographic pattern looks like a PCB but just off a bit in retention time. (Ive done both an acid/flourisil clean-up.) My gut tells me they're there, but I need evidence in order to report.

Are you more liberal in identifcation or strict in regards to retention times?

Any help is appreciated.

Thanks

[AICMM]

MarkRob,

Several things. Did you use internal standard to track any retention time shift? Does your peak pattern match if you shift the RT's. Do you think you have multiple arochlor's?

Arochlors came in many sizes and shapes and sometimes ended mixed (especially in transformers) so identification can be difficult. It is also known that Arochlors can weather so their pattern may not be an exact match in that sense either.

Possible to post the sample and a reference 1242 and 1260?

Best regards.

[jwhite80]

i find that sometimes when i analyze pcbs in oil that the retention shifts. i still call it a pcb if it matches any of the aroclors.

[chemwipe]

Hi there,

this post is related to one from earlier this week.

Can anyone tell me what approach they use to PCB identification and quantification (using ECD) I have analyzed samples which have peaks similar to, but not exact in shape to those of our reference aroclors.

Right above my desk, I have printouts of the most common Aroclors that I analyze for - Aroclors 1016, 1221, 1232, 1242, 1248, 1254, and 1260:



The chromatograms above are for identification of PCBs on an RTX-35 column.

Are you more liberal in identifcation or strict in regards to retention times?

If the pattern is there, then the pattern is there - you will get slight retention time shifts sometimes:

Here is a 1016/1260 10 ppm standard:


And here is a sample that contained Aroclor 1260:


And here is a 1254 10 ppm standard:


And a sample found to contain Aroclor 1254:


It would be hard to ignore the above patterns if going strictly off retention times!

Of course, as the one AICMM mentioned, an internal standard would be very useful in tracking any RT shifts.

Hope that helps!

John

[MarkRob]

it turns out that the caulking was over 60 years old!....I think a lot of the pcbs were breaking down (I didn't think that was possible).


what I get is a typical a1260 pattern, but it's clumpy. My chromatography is fine (from lcs and ccv). I took your advice and called it an aroclor.

thanks.

[chemwipe]

it turns out that the caulking was over 60 years old!....I think a lot of the pcbs were breaking down (I didn't think that was possible).


what I get is a typical a1260 pattern, but it's clumpy. My chromatography is fine (from lcs and ccv). I took your advice and called it an aroclor.

thanks.

Can you post chromatograms of your LCS (or CCV) and the sample? I'm curious to see how they look.

John

[AICMM]

Me too. (Oh boy, oh boy, oh boy!!!)

Best regards.