I have recently had requests for analysis of 18O in soil, stem and leaf 
water.  We have a Delta plus and GasBench II, but we do not have an 
extraction line. 

Do I have to purchase and set up an extraction line? (West et al. 2006 
Water extraction times for plant and soil materials used in stable 
isotope analysis.  Rapid Comm in Mass Spec.) 

Is there any reason why we can't just do a direct equilibration in the 
exetainer vials? (Scrimgeour 1995. Measurement of plant and soil water 
isotope composition by direct equilibration methods. Journal of Hydrology).

If direct equilibration is not the best option, what are your thoughts 
on this new method?  (Vendramini and Sternberg 2007. A faster plant 
stem-water extraction method. Rapid communications in Mass Spectrometry)

Thanks!