Shaun,

What do you mean by 'inconsistent' and 'baseline'? Out-of-the-box, the 
water concentration levels from my WVISS have not been that stable.  The 
isotopic value should be stable though.  I imagine different nebulizer 
sizes and dry air flow rates could produce more/less stable water mixing 
ratios.  Slow oscillations have been the sign of a partially clogged 
nebulizer.

I also found that the nebulizer cleaning instructions weren't that 
clear.  If you blow clean air through the dry air side-port, and cover 
the tip with a clean gloved finger, you should be able to blow air out 
the water intake line.  Similar to the purge conditions, but with more 
force.

Hope that helps.

Dr. Lisa Welp

On 8/11/16 12:00 AM, ISOGEOCHEM automatic digest system wrote:
> Date:    Thu, 11 Aug 2016 12:22:58 +1200
> From:    Shaun Barker<[log in to unmask]>
> Subject: inconsistent water vapour concentrations on LGR WVISS
>
> Hi,
>
> We’ve been having trouble maintaining a stable water vapor concentration baseline using our LGR WVISS.
>
> We suspect a partly clogged nebuliser, but after cleaning results haven’t improved, so we were wondering if anyone had encountered similar problems at any point and what the solution was (pardon the pun).
>
> Cheers,
>
> Shaun
> ---------------------------------------------------------
>
> Dr Shaun Barker
> Senior Lecturer, Earth Sciences
> School of Science
> University of Waikato
> Private Bag 3105
> Hamilton 3240
> New Zealand
> [log in to unmask]
>
> Ph: + 64 7 838 4514
> http://www.geochemistry.co.nz


-- 
-----------------------------------------
Dr. Lisa Welp, Assistant Professor
Earth, Atmospheric, and Planetary Sciences
Purdue University
[log in to unmask]
http://www.eaps.purdue.edu/research/lwelp/