Contamination and Troubleshooting: “Jack, did that really happen?”

I had to blog on this because this just happened again to my colleague Jack last week! Occasionally, a loose spring will make it into a limited volume insert. If overlooked, sample is loaded into this insert. As the spring soaks in the sample, a significant background signal can result. The green chromatogram trace shows background signal resulting from the spring and methylene chloride inside of an insert. The 2 ppm PAH standard chromatogram is shown for intensity reference and indicates the contamination is significant.

 

Although I haven’t experienced this myself, it is a great example of “checking the obvious” troubleshooting rule. Often we immediately think something much more serious and sophisticated is occurring when we run into trouble…like the GC inlet liner is dirty or the column has degraded. Based on symptoms, it is best to start with the simplest causes first…Is there sample in the vial?, Are we injecting the correct sample?, Is the syringe plugged?, Is the rinse solvent contaminated?…Is my sample soaking with a plastic spring?…

 

I learned this lesson the hard way, one time I spent two weeks trying to determine why I wasn’t getting any signal on my GCMS….the problem…the syringe was plugged! You better believe I watch my syringe make an injection when I start a sample queue.

 



 

2 Responses to “Contamination and Troubleshooting: “Jack, did that really happen?””

  1. Doron says:

    Hi, Julie, How did the spring get into the limited volume insert?!

  2. The insert and spring are already attached.
    They are packaging in a plastic bag in 100 quantities for example.
    Most of the time there are a couple of springs that become detached and sometimes end up inside of a glass insert.

    Most people know this happens and simply don’t use these or remove the spring. I think the reason why this occurs to Jack is because he will take a whole tray of vials and fill them with inserts at one time. Because he isn’t placing the insert into the vial and then adding sample directly, my guess is it is easier to miss the extra spring…

    thank you for your comment
    Julie

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