6 Replies Latest reply on Nov 20, 2018 11:18 AM by srstrangis

    GC and Helium shortage

    srstrangis

      Hi,

       

      we are currently unable to get Helium. We'll run our Helium gas inventory in a few weeks. Between other applications for our facility, it is used as a carrier gas on our GCs for solvent analysis (validated method). I'm copying our method below. Would it be best to use N2 or H2? How do I calculate the equivalent flow. Any other option?

      Thanks in advance.

       

      1.1         Injector

      Mode: splitless

      Temperature: 250 oC

      Carrier gas: Helium

      1.2         Column

      Type: fused silica capillary

      Model:  DB-200 (J&W p/n 122-2033),

      Nominal Length: 30m

      Nominal diameter: 0.25mm

      Nominal film thickness: 0.5 µm

      Mode: constant pressure, 15 psi.

      Nominal initial flow: 1.4 mL/min.

      1.3         Detector

      Type: FID

      Temperature: 300oC

      Hydrogen flow: 40 mL/min

      Air flow: 350 mL/min

      Mode: constant makeup flow

      Makeup gas: Nitrogen (30 mL/min)

      1.4         Temperature profile

      Initial temperature: 40oC for 2 minutes

      Ramp:  increased from 40oC to 130oC at a rate of 20oC/min

      Ramp time: 4.5 minutes

      Post temperature:  maintained at 130oC for 5.5 minutes.

        Total run time:  12 minutes

        • Re: GC and Helium shortage
          james_jenkins

          Hi srstrangis,

          I have updated the tags for better visibility . Please see the below discussion link on using hydrogen as a carrier . I would suggest that you speak with one of our column specialist at Agilent if you are going to convert to another carrier gas type. Column size changes maybe required depending on your application. A gas change is most often, not a straight forward change.  I have also included a link to our GC calculators as there is a flow tool that will allow you to calculate column flow , head pressure etc.

           

          Columns, Supplies, and Standards Support | Agilent

           

          GC Calculators | Agilent

           

          Using Hydrogen as Carrier Gas for GC and GCMS

           

          Regards

          James

            • Re: GC and Helium shortage
              srstrangis

              James,

               

              Thank you for your help.

               

              Roberto

              (Contact Details deleted by Moderator)

              • Re: GC and Helium shortage
                srstrangis

                James,

                 

                I was able to use the same column. I had to reduce the inlet pressure from 15 psi to 11 psi to keep the speed within the recommended range for H2.

                The areas are now 5 times larger (higher sensitivity). The peaks do not resolve at baseline. I'd like to reduce the injection volume from 1 uL to 0.5 uL. The problem is that the autosampler options are 0.2 uL and 1uL. There is nothing in between. Is there any workaround with the chemstation software to inject 0.5 uL with a 10 uL syringe?

                 

                I know that one option is to use 5 uL syringes.   

                  • Re: GC and Helium shortage
                    james_jenkins

                    Hi srstrangis,

                    The smaller syringe is one way. Depending on the autosampler you have , you may not be able to specify the smaller injection volume without changing syringe to 5ul. You could also stay with the injection volume, but change the method to split . The split ratio would have to be high enough to maintain a recommended total flow of 15 to 20 ml/minute on the inlet. I hope that helps. Let us know what you find.

                    James

                • Re: GC and Helium shortage
                  james_jenkins

                  Hi srstrangis,

                  I have marked your post as assumed answered, please feel free to post again if you need more information.

                  Regards

                  James

                    • Re: GC and Helium shortage
                      srstrangis

                      Hi James,

                       

                      I'm trying to change the default injection syringe size from 10 ul to 5 ul. The Openlab chemstation (Configuration -> ALS)  beeps when to make a syringe size entry, even if I type the existing one. How do I change the syringe size in the software?

                       

                      Also, we have an 7673 Injector. On the Configuration -> ALS tab it shows G2613A installed. I don't know where to update it.

                       

                      Regards,

                       

                      Roberto

                       

                      Roberto Strangis, M.S.

                      (Personal Contacts Removed by Moderator)