Stable Isotope Analysis

Question 1

How does reaction rates between isotopes vary?

Answer 1

Heavier isotopes react more slowly because they have greater bond strengths.

Question 2

How do fractionations vary by reactions or factors?

Answer 2

Fractionations in chemical processes are generally larger than those in physical processes and enzyme-catalysed reactions. Temperature changes may affect fractionations in enzyme-catalysed reactions.

Question 3

What is the composition of the first column?

Answer 3

After autosampler and He, ceramic outer tube, glassy carbon inner tube, glassy carbon chips within a column at 1230 degrees C.

Question 4

What is the abundance and standard of carbon?

Answer 4

C-12, 98.982; C-13, 1.108
PDB

Question 5

What is the abundance and standard of nitrogen?

Answer 5

N-14, 99.630; N-15, 0.366
N2, air

Question 6

What is the abundance and standard of oxygen?

Answer 6

O-16, 99.763; O-17, 0.0375; O-18, 0.1995
VSMOV, PDB

Question 7

What is the abundance and standard of sulfur?

Answer 7

S-32, 95.02; S-33, 0.756; S-34, 4.210
CDT (Canon Diablo Troilite)

Question 8

How are EA-IRMS structured?

Answer 8

Autosampler with solid sample, elemental analyser: oxidation, reduction, separation (GC); open-split interface (injects helium and standard gas) and IRMS.

Question 9

Raylrigh fractionation formula

Answer 9

dlogR/dlogN = d(lambda)/dlogN = (alpha*-1)

Question 10

R

Answer 10

ratio of numbers

Question 11

alpha*

Answer 11

equilibrium fractionation factor

Question 12

lambda

Answer 12

logR

Question 13

lambda-space

Answer 13

representation of (lambda) H-2 vs O-18

Question 14

relation between H-2 and O-18

Answer 14

d(lambda)H-2/d(lambda)O-18 = (alpha-1)H-2 / (alpha-1)O-18

Question 15

Translation of lambda-space to delta-space
delta = {(R-R(standard)/R(standard}

Answer 15

d(lambda) = dlog(1 + delta/10^3) = (d(delta)/10^3) / (1+(delta)/10^3)

Question 16

Harmon Craig’s relationship, GMWL (Global Meteoric Water Line)

Answer 16

delta(H-2) = 8 x delta(O-18)+10