171Chemistry and Nuclear Forensic Science
Most resins used in the radioanalytical laboratory encompass 100 to 200 mesh, and
d
ry
r
esin
b
eads
s
well
w
hen
i
mmersed
i
n
a
n
a
queous
me
dium.
T
he
e
xtent
o
f
t
his
s
welling
i
s
c
ontrolled
b
y
t
he
d
egree
o
f
c
ross-linking
o
f
t
he
p
olymer
s
trands,
w
hich
i
s
a
f
unction
o
f
t
he
p
ercentage
o
f
d
ivinylbenzene
us
ed
i
n
f
abricating
t
he
p
olymer.
T
ypical
r
esins
us
ed
i
n
t
he
r
adioanalytical
l
aboratory
a
re
c
ross-linked
b
etween
4
%
and 12%. The higher cross-linked resins are generally more selective, but the reac-
tion
k
inetics
a
re
s
lower.
L
ower
c
ross-linked
r
esins
e
xchange
q
uickly
a
nd
a
re
p
ar-
ticularly
us
eful
i
n
s
orbing
l
arge
i
ons.
H
owever,
a
d
rawback
i
s
t
hat
t
he
v
olume
o
f
t
he
l
ow-cross-linked
b
eads
ca
n
v
ary
g
reatly
w
hen
t
he ...