Rit (Vísindafélag Íslendinga) - 01.06.1976, Blaðsíða 23

The primary standards used for our deuterium measurements,
were two standard water samples, NBS 1 and NBS 1A, from the
National Bureau of Standards, which according to Craig (1961)
have deuterium concentration 8D(nbs n — — 47.6%0 and 8D(NBg 1A) =
— 183.3%0 relative to SMOW.
As a secondary comparison standard for daily use geothermal
water from a 2000 m deep borehole in Reykjavík, Hátún G—4, was
chosen. This standard, in the following called TS — standard, has
been estimated to have 8d(ts) = — 65.0%o relative to SMOW.
All samples presented in this paper were processed and analysed
in duplicate or even replicate, if the difference between the ana-
lysis in duplicate was larger than 2%0.
Regarding standards used in the oxygen isotope work, the reader
is referred to Dansgaard’s work (1961).
2. 3 The accuracy of the measurements.
The daily TS — standard used for the deuterium measurements
must be corrected for instrumental errors caused by different inlet
systems and time variations. Time variations are considerable, espe-
cially if the same standard is used for more than one day, as often
happens.
Such corrections are made by daily preparation of two TS —
standards and these two standards are compared with the one used
with the samples.
As this also makes it possible to estimate the reproducibility of
the preparation and measurements, this part of the procedure is
described in detail.
A schematic drawing of the double inlet system on the spectro-
meter is given in Fig. 1.
The secondary standard (TSA) used with the samples to be mea-
sured is put in part A. The two standards prepared and used to
make daily corrections are put in part B and compared with TSA,
one before (TSj) and one after (TS2) measurements are carried
out every day. As a daily correction for TSA, ACOrr, we use then
A _ (TSa - TSí) + (TSa - TS2)
corr n
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