Print

Print


Thanks, Matheus.

I've got an older GCC III that I have to manually adjust.

So, if I do a series of on/offs, 8 refgas peaks, of increasing size from 1 V to 10 V I get a much smaller effect of ~ 0.3 permil/V with an H3 of ~ 3.2 applied. This same H3 is applied to my alkane standards, but I still have the effect I described above. 

Grumble...




On Mon, Jan 16, 2017 at 4:33 PM, Matheus Carvalho <[log in to unmask]> wrote:
Jeff, in my case Isodat changes automatically the peak sizes. I am using Conflo IV. Maybe you are using an older Conflo?

Matheus C. Carvalho
Senior Research Associate
Centre for Coastal Biogeochemistry Research
Southern Cross University
Lismore, NSW, Australia
61-4-8899-0092


Book: Practical Laboratory Automation Made Easy with AutoIt


On Mon, Jan 16, 2017 at 11:54 PM, Jeff Salacup <[log in to unmask]> wrote:
Hi Matheus,

Well, I manually change the size of the refgas peaks during the H3 sequence. To do what you suggest, would I do a series of on/offs and change the refgas peak size there? Would the H3 correction be applied to this data?

Also, "when I do the H3 correction"... isn't the H3 correction something ISODAT automatically does once you perform and save an H3 sequence?


Thanks!

On Sun, Jan 15, 2017 at 5:43 PM, Matheus Carvalho <[log in to unmask]m> wrote:
Do you see the same effect by manually changing ref gas peaks intensities? By checking this you can evaluate if the problem is in the standards or in the sensor. Also, When I do the H3 factor correction it gets really good. So maybe you should try again...
Good luck,

Matheus C. Carvalho
Senior Research Associate
Centre for Coastal Biogeochemistry Research
Southern Cross University
Lismore, NSW, Australia
61-4-8899-0092


Book: Practical Laboratory Automation Made Easy with AutoIt


On Mon, Jan 16, 2017 at 9:33 AM, Jeff Salacup <[log in to unmask]> wrote:
Hi Isotopers,

Me again.

I've got a Thermo Trace GC Delta V Advantage running leaf wax dD. I do daily H3 corrections - averaging ~3.2 permil/V. However, if I run a dilution series of our standards I still get a powerful peak size effect: r2 always greater than 0.9 and slopes of ~ 1-2 permil per V for a dynamic range from 2-20 V. We do aim to have our unknown peak sizes all very close, but I'd still love to get rid of or control for this effect.

Any thoughts?

Thank you, once again, for any wisdom imparted!

--
Jeff




Two things are infinite: the universe and human stupidity; and I'm not sure about the universe. - Einstein



__________________________________________________________________
Jeff Salacup, Ph.D.
Stable Isotope & Biogeochemistry Lab Manager
UMass-Amherst





--
Jeff




Two things are infinite: the universe and human stupidity; and I'm not sure about the universe. - Einstein



__________________________________________________________________
Jeff Salacup, Ph.D.
Stable Isotope & Biogeochemistry Lab Manager
UMass-Amherst





--
Jeff




Two things are infinite: the universe and human stupidity; and I'm not sure about the universe. - Einstein



__________________________________________________________________
Jeff Salacup, Ph.D.
Stable Isotope & Biogeochemistry Lab Manager
UMass-Amherst