6 Replies Latest reply on Mar 15, 2019 1:51 AM by dmarchini

    Trying to calibrate my GC 6850

    elirodrigues

      Hi everyone,

       

      I'm having some problem with my method.

      Not sure exactly what it is:

      Couple of days ago I've replaced the column of my GC-6850 with a shorter column ( 30m - 320mm).

      I had to integrate the peaks with the new length of the column.

      I normally use two methods to run my samples:

      One is longer (ramp) and the other one is shorter with no ramp.

      I can calibrate the longer method with no problems.

      But when i load the shorter method it is not possible to calibrate the machine.

       

      I've noticed that when I run a blank test (no injection) on short method it picks up the compound that I'm analyzing.

      When I run the same Blank on longer method the peak disappears.

       

      Standard Run (104ppb)

       

       

      Blank Run (no injection)

       

       

      I'm afraid that I've got a contamination and the peak on short run is not correctly integrated.

       

      Sorry I can't explain better.

      I'm very new in this field and I'm looking for some help in trying to understand better my software.

       

      Please help.

       

      Tanks.

        • Re: Trying to calibrate my GC 6850
          james_jenkins

          Hi elirrodrigues,

          I updated the tags for better visibility.

          Regards

          James

          • Re: Trying to calibrate my GC 6850
            dmarchini

            Hello

            the area amount of the starndard is the one you expected? I don't see much difference between the blank and the std run, its seems like the FID is working but there is a leak somewhere, maybe in the injector? No solvent peak?

              • Re: Trying to calibrate my GC 6850
                elirodrigues

                Hi there,

                 

                thanks for replying.

                 

                When I run the standard it gives me the correct amount in all three runs that I perform before start the tests.

                 

                We work with air samples.

                The samples are collected using PP plastic syringes;

                They are sent to the lab for testing;

                The syringe is then attached to the inlet port of the GC and the sample is injected manually;

                2ml of sample is hold in the 6 port valve (adapted for our type of sampling Technic);

                Once the GC is ready the sample is taken automatically from the 6 port valve into the column.

                  • Re: Trying to calibrate my GC 6850
                    dmarchini

                    For our standards, a peak as you show in the chromatogram is unacceptable, its seems more like a baseline noise doubled peak.....I would try anyway to get better response and an accettaple peak size/shape increasing at least 5 times the injected volume or doin a splitless injection injectin high volume.

                     

                    We work with air samples collectin it in TEDLAR BAGS with septum of the volume of 5 liters using a pump or without a pump if the gas emission is under pressure then we directly inject using these Agilent gas syringes

                     

                    -P/N 5190-1523 500uL gas syringe

                    -P/N 5190-1528 1000uL ga syringe

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