We have successfully used TC/EA-IRMS for simultaneous d2H and d18O
analysis in water for a few years. We have accomplished additional tests
based on the nice work of Gehre et al (2004), and the results are
summarized in a manuscript for publication. We used the three
international standards to calibrate several working standards. We also
reused the three standards a few times from several months to one year
after the first use, still pretty good. Our working standards are all
stored in individual ampoules (1.5ml). We use two working standards for
sample calibration and one more in the middle for checking.

Feng



                                                                                                                      
  From:       Ulrike Schulte <[log in to unmask]>                                                                  
                                                                                                                      
  To:         [log in to unmask]                                                                                 
                                                                                                                      
  Date:       12/09/2008 04:25 AM                                                                                     
                                                                                                                      
  Subject:    [ISOGEOCHEM] on-line analysis of water with TC/EA - basic questions concerning standards                
                                                                                                                      





Dear listmembers,

from next year on we want to start on-line water analysis (delta18O,
deltaD) with a TC/EA (equipped with a liquid autosampler) coupled to a
MAT 253.
We know the publication of Gehre et al. (2004) about continous flow
analysis of water sample but we would like to get in contact with people

who already use this method successfully.
At the moment we are discussing intensively how to do the calibration of

the system with SMOW, SLAP and GISP and how to store these reference
materials after the ampule has been opened: Is it better to store it in
a large bottle or vial (25 ml, glas or plastic?) and to reopen this
bottle regularly for calibration checks or should we split the water in
for example 1 ml portions and store it in very small vials?
How often do you check your system with these RMs?
How many secondary standards do you use, what?s the difference in their
isotopic composition and how did you produce them?
Probably a lot of questions will rise during the next months and we will

be glad about any information, literature or warnings....

Thanks in advance and have a nice day

Ulrike Schulte



--
------------------------------------------------
Dr. Ulrike Schulte
Institut für Geologie, Mineralogie und Geophysik
Lehrstuhl für Sediment- und Isotopengeologie
Ruhr-Universität Bochum
Universitätsstr. 150

D-44801 Bochum

Tel.: 0234/32-25454
Fax.: 0234/32-14571
------------------------------------------------




----------------------------------------
Feng H. Lu, Ph.D.
Stable Isotope Lab
Ground Water and Ecosystems Restoration
Shaw Environmental
P.O. Box 1198
Ada, OK 74820-1198
USA,
(580)436-8676