δ^{18}O
The ^{18}O concentration of VSMOW is
2005.2 ppm which is defined as δ^{18}O = 0.0
‰ on the VSMOW
scale.
Conversion from δ^{18}O to ppm ^{18}O
is linear:
conc ^{18}O [ppm] = (1000 + δ^{18}O
) x 2.0052
δ^{18}O = 0 ‰ (VSMOW)
is equivalent to an ^{18}O concentration of
2005.2 ppm
δ^{18}O = 55.5 ‰ (SLAP)
is equivalent to an ^{18}O concentration of
1893.91 ppm
Our lab water has δ^{18}O =
7.75 ‰ ( equivalent to an ^{18}O
concentration of 1990 ppm)
δ^{18}O = 1000 ‰ is
equivalent to an ^{18}O concentration of 0 ppm
thus ^{18}Ofree water.
Picarro
claims their L2130i
CRDS machines have standard deviations of 0.03
‰ for δ^{18}O.
this is equivalent to a standard deviation of 0.06 ppm at
a concentrations around 1900 to 2000 ppm !!
Simple conversion of ^{18}O concentration
to δ notation on the VSMOW scale
δ^{18}O [‰]
= conc ^{18}O / 2.0052 
1000
(conc ^{18}O in ppm)
δ D = δ ^{2}H
The deuterium
(D, ^{2}H) concentration of VSMOW is 155.76
ppm which is defined as δ ^{2}H = 0.0
‰ on the VSMOW scale
The conversion from δ ^{2}H to
^{2}H concentration in ppm is linear:
conc ^{2}H [ppm] = (1000 + δ
^{2}H) / 6.420135
δ ^{2}H = 0 ‰ (VSMOW) is
equivalent to a ^{2}H concentration of 155.76 ppm
δ ^{2}H = 427.5 ‰ (SLAP) is
equivalent to a ^{2}H concentration of 89.173 ppm
Our lab water has δ ^{2}H
= 52.3 ‰ ( equivalent to a ^{2}H
concentration of 147.6 ppm)
δ ^{2}H = 1000 ‰ is equivalent to a
^{2}H concentration of 0 ppm thus deuteriumfree
water.
Picarro claims their L2130i CRDS machines have standard
deviations of 0.3‰ for δ ^{2}H.
this is equivalent to a standard deviation of 0.047 ppm at
concentrations around 90 to 160 ppm !!
Simple conversion from ^{2}H concentration
in ppm to δ ^{2}H in ‰ on the VSMOW
scale
δ ^{2}H [‰]
= ppm D x 6.420135  1000
100% heavy
water (D_{2}O) is equivalent to a ^{2}H
concentration of 1000000 ppm.
This corresponds to δ ^{2}H
[‰] =1000000 x 6.420135  1000 = + 6419135
‰ !! (almost 6.5 Mio ‰)
Since the conversions are linear, you can calculate
linear mixtures of two solutions in either
concentrations or in δ notation.
e.g. a 1+1 mix of SLAP (δ ^{2}H =
427.5 ‰) and VSMOW (δ ^{2}H
= 0 ‰) :
δ ^{2}H = (1x(427.5)+1x0) / (1+1) =
213.75 ‰ or (1x89.173 ppm + 1x 155.76 ppm) / (1+1)
= 122.4665 ppm
δ ^{2}H = 122.4665x6.4201 1000 = 786.25 
1000 =  213.75 ‰
1 part heavy water ( δ^{2}H = 6419135
‰ ) + 99 parts pure water ( δ^{2}H =
52.3 ‰  this counts for our lab water)
= (1x6419135+99x(52.3)) / (1+99) = + 64139.573 ‰
so a 1% D_{2}O solution has a δ ^{2}H
= + 64140 ‰ or 10147 ppm ^{2}H
If you dilute more to get a 0.01% D_{2}O
solution (1 part heavy water + 9999 parts pure
water)
= (1x6419135+9999x(52.3)) / (1+9999) = + 589.619 ‰
so a 0.01% D_{2}O solution has a δ ^{2}H
= + 589.62 ‰ or 247.61 ppm ^{2}H
If you have enough house standards to choose from, you
can mix your own VSMOW
and SLAP
All δ values on this page are related to the VSMOW
scale
original time stamp 06.April 2016, edit 7, 15 Feb
2018, 06 Sep 18, 29Jan19, 22.Jul20
