HI Herb--

Are the ratio's ok???  I'd expect the top of the peak to rise a bit during the
pulse, but not bounce too much.  Assuming there's no weird vibration that the
mass spec is picking up on, and it's happily centered on the peak, potential
problems with the split:

Gunk builds up (sample side).  Depending on what you're pushing through the
Conflo, keep an eye out for this.

Partial clog in mass spec line--clip a little of the end off (with mass spec
closed off) to see if that helps.

He line sitting on bottom of split--close is ok, but it can be partially
blocked. By the same token, if it's too high, the He won't sweep out the gases
at the bottom of the split very well.

Also check for air leaks in case the valve is leaking a little.

good luck

gerry


Quoting Herbert Tobias <[log in to unmask]>:

> Hello all,
>
> I would like to ask a question about reference CO2 gas pulse shapes using
> the Conflo III device on a MAT 253.  Has anyone seen the following issue
> and "solved" it:
>
> The problem I have is that the gas pulses when equilibrated is a bit
> noisy.  So when you see the CO2 gas pulses generated, they look a bit
> jumpy. In other words, they are not smooth on the top.  It isn't an issue
> as far as reproducibility, they still give good zero enrichment numbers.
> I guess this is more of an "aesthetic" issue.
>
> I tried changing head pressures of the He gas and CO2 gas, plus distances
> of the capillaries in the "open split" tube to no avail.  Any hard
> experience with this issue will be greatly appreciated.
>
> sincerely your disgruntled,
> -Herb
> Cornell University
>