The available datasets on GISP intercomparison material would suggest
the following isotopic composition of GISP relative to VSMOW in permille:
delta2H=-189.5+-1.0 permille
delta18O=-24.77+-0.05 permille
considering the datasets [3] and [4] below.
Best regards,
                        Manfred Groening
++++++++++++++++++++++++++++++++++
Manfred Groening
Isotope Hydrology Section --- International Atomic Energy Agency
P.O.Box 100   A-1400 Vienna   AUSTRIA
Phone: ++43-1-206021740    Fax:  ++43-1-20607
e-mail: [log in to unmask]
+++++++++++++++++++++++++++++++++

For your reference:
GISP - Greenland Ice Sheet Precipitation: water, prepared 1976 by 
W.Dansgaard, University of Copenhagen, melting a sample of Greenland firn. 
Distributed since 1977.
Isotope results of GISP intercomparison material were published in:
1.
Gonfiantini, R., The delta-notation and the mass-spectrometric measurement 
techniques,
in: Stable Isotope Hydrology, Deuterium and Oxygen-18 in the Water Cycle, 
scientific editors J.R. Gat and R. Gonfiantini, 35-84, International Atomic 
Energy Agency, Vienna, 1981.
Preliminary values, no standard deviation stated:
delta2H=-189.8 permille vs. SMOW (n=11)
delta18O=-24.85 permille vs. SMOW (n=13)

2.
Gonfiantini, R., Report of the "Advisory Group Meeting on stable isotope 
reference samples for geochemical and hydrological investigations", IAEA, 
Vienna, 1984.
Normalization of data using SLAP was suggested (data reported using the 
normalized VSMOW/SLAP scale, stating 1sigma standard deviation) after 
removal of three outliers (2sigma-criterium), raw data are listed :
delta2H=-189.7+-1.1 permille vs. VSMOW (n=45)
delta18O=-24.79+-0.09 permille vs. VSMOW (n=49)

3.
Proceedings of an IAEA consultants meeting "Reference and intercomparison 
materials for stable isotopes of light elements", IAEA-TECDOC-825, IAEA, 
1995.
Using the same dataset, outliers were excluded after two iterations of the 
2sigma-criterium:
delta2H=-189.73+-0.87 permille vs. VSMOW (n=44)
delta18O=-24.784+-0.074 permille vs. VSMOW (n=46)

4.
Araguas Araguas, L. and Rozanski, K., Report of the "Interlaboratory 
comparison for deuterium and oxygen-18 analysis of precipitation samples", 
IAEA, 1995.
New dataset based on an  interlaboratory comparison performed by 
laboratories contributing to the IAEA Global Network of Isotopes in 
Precipitation (GNIP), data reported in the normalized VSMOW/SLAP scale, 
stating 1sigma standard deviation, after removal of three outliers 
(2sigma-criterium):
delta2H=-189.17+-0.57 permille vs. VSMOW (n=19)
delta18O=-24.762+-0.036 permille vs. VSMOW (n=20)


>
>Dear my friends:
>
>    Could some one tell me the latest evaluation on isotopic
>composition of GISP standards? I will appreciate your responce.
>
>Best regards,
>
>Noriyuki Tanaka
>Hokkaido Univ.
>Sapporo Japan
>email: [log in to unmask]
>