Chromatography Forum

Good morning,
We are currently trying to get Method 552.3 MDLs to work and are having trouble with Tribromoacetic acid, Chlorodibromo acetic acid and Bromodichloroacetic acid. Does anyone have any suggestions to try?
Thanks,
Lisa

Good morning,
We are currently trying to get Method 552.3 MDLs to work and are having trouble with Tribromoacetic acid, Chlorodibromo acetic acid and Bromodichloroacetic acid. Does anyone have any suggestions to try?
Thanks,
Lisa

Is this the MRL study?

If so, are you using the primary source standard or the secondary source (QCS) standard to spike the MRL extractions?

We are seeing that the second source is slightly different from the primary and gives us some trouble with percent recovery, so we will try again using the primary source to spike with.

We are using the primary source and aren't getting a decent enough response at the MRL to be reproducible.

What column are you using and what conditions?

We are using the columns stated in the method and we tried the temperature program stated. We are now trying different temperature programs. We are making one injection onto a guard column which is then put in a y-splitter that has the two columns attached. We have tried injecting more volume since it is split between two columns but we just aren't getting very good reproducible sensitivity.

When you said you tried injecting more volume because of the split....did you calculate the vapor volume? Because if the vapor volume exceeds the capacity of your liner (i guess you are using a SSL-Injector?) you get a backflush and the sample will get stuck in the non-heated gas pipes. Even if you don't experience weird peaks in the next runs i would strongly recommend to change the liner and clean at least the injector chamber since it is very easy to use to much volume. So if you used a 2 mm quartz liner like in the method you can just inject tiny ammounts to get reproducible results. Use a solvent expansion calculator to check if everything is ok.

http://www.restek.com/chromatogram/view/GC_EV01006

This is the column setup we are using, but we switched to hydrogen carrier gas to get better sensitivity. Using the same cyclo liner listed in the link.

You will need to experiment with the flows and temp program just a little to get complete separation.

If using and Agilent, it should be able to calculate the proper head pressure to deliver the needed flow to both columns connected to a single inlet.

Just curious, what is your calibration range?

Hi,

can I ask you a question related to EPA 552.3 but not to the topic?

I am facing issue with the storage of HAA5 standards in MTBE? Literally after 24 hrs despite having tried anything (high temp, low temp, screw caps, crimped top caps) the Stock solutions have been compromised.

Does anyone have a tip/trick for the storage or should I live with opening new standards in every batch?

Thanks.