Chlorobenzene contamination in VOA samples and blanks - Chromatography Forum

Chlorobenzene contamination in VOA samples and blanks

Discussions about sample preparation: extraction, cleanup, derivatization, etc.

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We have a quirky problem lately. We have been have some 524 drinking water samples and trip blanks that have hits for chlorobenzene. I have encountered the normal dichloromethane, acetone, and chloroform contaminates in the past but this one is odd since it is not used that much in things I can find.

My one suspect is that samplers have contaminated their 1+1 HCl with gasoline from a fillup on the route, and the benzene is forming chlorobenzene in the presence of the acid. Anyone else think that could possibly happen? I only saw something similar once before when we had methanol contamination of the acid and it formed chloromethane.

Are there any other uses of chlorobenzene I might be overlooking that would cause contamination?
The past is there to guide us into the future, not to dwell in.
If chlorobenzene is used in printing inks and you have printed labels on plastic sample containers.........

JMB
My copy of Morrison and Boyd says that you can chlorinate a benzene ring with chlorine (Cl2, dissolved) IF you have Fe or FeCl3 present. It says nothing about being able to chlorinate a benzene ring with only hydrochloric acid. You need electron-deficient chloride to attack the ring.

Reactions of strong acids and alcohols are a different animal. You can get methyl chloride from methanol and hydrochloric acid.

My guess is like what JMB is saying. It's probably being leached into your samples from the environment somewhere/somehow.
rb6banjo wrote:
My copy of Morrison and Boyd says that you can chlorinate a benzene ring with chlorine (Cl2, dissolved) IF you have Fe or FeCl3 present. It says nothing about being able to chlorinate a benzene ring with only hydrochloric acid. You need electron-deficient chloride to attack the ring.

Reactions of strong acids and alcohols are a different animal. You can get methyl chloride from methanol and hydrochloric acid.
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As a chemist i second this. It is unlikely/impossible to form chlorobenzene out of benzene and HCl.
I have had one instance of chlorobenzene contamination in a VOA trip blank. No idea where it came from but I assume it came from a solvent along the way. I often have THF and DCM in blanks provided by contract samplers. They must use water systems with pvc supply pipes.
In the past year I have had several cases of soil samples and equipment rinsates with C5 to C10 straight chain aldehydes, sometimes fairly high levels. I'm still trying to figure out where that comes from.
JMB wrote:
If chlorobenzene is used in printing inks and you have printed labels on plastic sample containers.........

JMB


Using glass VOA vials with teflon lined septa so hopefully it isn't a leaching problem.

We have the same vials in all of our locations but only two outer offices are having the problems. When we replaced their acid used to preserve the samples the problem went away, then returned after a few weeks. We tested one of their bottles of HCL and found some contamination in it but not in every location. So this one is still driving us crazy.
The past is there to guide us into the future, not to dwell in.
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