Chromatography Forum

Anyone done low level chlorine by GC? I was thinking about ECD but I am concerned about reaction with the Ni63. Any other options?

Best regards.

Here I injected 0.005ng of organochlorine pesticides and get a very good ICAL using ECD.
For PCB congeners also 0.005ng is a good limit.
"I was thinking about ECD but I am concerned about reaction with the Ni63"
I don't believe that is possible.

ECD is an excellent tool for analysis of chlorine containing compunds. Note http://en.wikipedia.org/wiki/Electron_capture_detector. Be aware that it has some sensitivity to other compunds, particularly those with pi electrons and filled p orbitals.

I assumed you were discussing "chlorine" gas, not an organochlorine compound. My only experience was with an old ( PYE 104 ) system analysing reactor products - we had switched all the system to glass and PTFE - can't remember the detector type.

The problem was corrosion of the detector, as ambient moisture would "stick" to the detector components and form HCl, which then corroded the detector when it was turned off. Detector lasted about 2 months, IIRC.

I suspect there are superior detector options these days for corrosive gases.

Bruce Hamilton

Hi

Found an article on Cl gas with GC, no idea how it works and not much details:


Journal of Analytical and Applied Pyrolysis
Volume 51, Issues 1-2, July 1999, Pages 167-179

Chlorine gas recovery from polyvinyl chloride
Sanae Horikawa, Yoshifumi Takai, Hiroichi Ukei, Naoto Azuma and Akifumi Ueno

Department of Materials Science, Faculty of Engineering, Shizuoka University, 3-5-1 Johoku, Hamamatsu, Shizuoka 432-8561, Japan


Available online 24 May 1999.


2.2. Measurement of hydrogen chloride and chlorine gas
The amount of HCl evolved from the PVC resin was measured by two methods; in the first method, gas chromatography (GC-390B, GL Science) was employed using a column packed with Daifl oil (no. 10) dispersed on Flusin T 60/80. All of the tubes and valves in the GC machine were coated with teflon to protect against corrosion caused by hydrogen chloride and chlorine gas. In the second method, liquid chromatography (Ion Analyzer-PIA-1000, Shimadzu) was employed, where HCl was trapped in distilled water to be submitted to the analyzer. The amount of Cl2 gas recovered from resultant metal chlorides was also directly measured by GC using the same column as described above. Exhaust gases containing chlorine were trapped by an aqueous solution of potassium iodide (KI) before release into air to avoid the diffusion of harmful chlorine in the atmosphere.

To all,

Thanks for the replies. I should have been more specific, chlorine gas not organochlorine compounds.

I have taken note of the steps to protect the system. The corrosive nature is what is making me concerned about the use of conventional ECD.

Best regards.

hmm

some speculative thoughts:

Once the gas reach the ECD, the ECD will be heated and you could put the makeup gas flowrate in the upper bracket ie sacrificing some sensitivity to minimise contact with detector wall.

Suspect you would have a gas trap that also catches potential moist in the makeup/column gas preventing HCl formation.

Perhaps your ECD supplier has some info if you draw blank in this forum.

As it's only low concentrations, the issue is what makes up the bulk of the sample. If it's not moisture or high/low pH materials, I would use a PTFE packed column and still use make up to purge the detector whilst in use, and at a higher flow during cooldown.

I can't remember the concentrations I was playing with but I think it was 0.5 - 2 %.

The other issue was corrosion of the sampling valve, but I used a six port 1/16" line all-PTFE valve from either Valco or Rheodyne and 1/16^ 10-20 thou PTFE lines that withstood head pressure OK. I also had a cross purge setup on the sample system so it could be flushed with dry nitrogen. That aspect worked very well.

Please keep having fun,

Bruce Hamilton