Spectrofluorometric Determination of Hydrogen Peroxide

Abstract

A Spectrofluorometric method for microdetermination of H2O2 has been developed. The method is based on the oxidation of hydrogen peroxide with ceric ion in acid solution and measurement of the fluorescence during titration of the Ce(III) ions produced. The fluorescent species have excitation and emission maxima at 260 and 360 nm, respectively. The detection limit of measurement by this method was 0.1 ppm hydrogen peroxide.

Full text

Journal
of
Fluorescence,
Vol.
8, No. 2,
1998
Spectrofluorometric Determination
of
Hydrogen Peroxide
B.
Demirata-Oztiirk,
1,4
G.
Ozen,
1
H.
Filik,
2
I.
Tor,
2
and H.
Afsar
3
Received October
27,
1997;
accepted
May 14,
1998
A
Spectrofluorometric method
for
microdetermination
of
H
2
O
2
has
been developed.
The
method
is
based
on the
oxidation
of
hydrogen peroxide with eerie
ion in
acid solution
and
measurement
of
the
fluorescence
during titration
of the
Ce(III) ions produced.
The fluorescent
species have exci-
tation
and
emission maxima
at 260 and 360 nm,
respectively.
The
detection limit
of
measurement
by
this
method
was 0.1 ppm
hydrogen peroxide.
KEY
WORDS: Hydrogen peroxide; eerie
ion;
Spectrofluorometric titration.
INTRODUCTION
Hydrogen peroxide
is an
important chemical
in en-
vironmental
and
biological studies
and it is
also
used
as
a
chemical
in
many industries, such
as
epoxidation,
hy-
droxylation, oxidation,
and
reduction. Therefore
a
rapid
and
simple method
for its
microlevel determination
is
needed. Determination
of
hydrogen peroxide
is
usually
based
on the
production
of
colored
peroxy
compounds
or on its
oxidizing
and
reducing properties.
For the
sen-
sitive determination
of
hydrogen peroxide chemilumi-
nescence[l,2], spectrophotometic
[3-6],
and
spectro-
fluorimetic
[7-10],
continuous-flow analysis
[11],
flow
injection
[12],
and
kinetic methods
[13]
have
also
been
reported.
In
the
present study
a
sensitive
and
simple spectro-
fluorometric
method
for the
determination
of
hydrogen
peroxide
was
developed. This method
is
based
on the
oxidation
of
hydrogen peroxide with eerie
ion in
acid
solution
and
determination
of
Ce(III) ions produced
by
1
Faculty
of
Science
and
Letters, Istanbul Technical University,
Mas-
lak, Istanbul, Turkey.
2
Faculty
of
Engineering, Istanbul University, Avcilar, Istanbul,
Tur-
key.
3
Faculty
of
Science
and
Letters,
Yildiz
Technical University, Sisli,
Istanbul, Turkey.
4
To
whom correspondence should
be
addressed
at
Istanbul Technical
University,
Department
of
Chemistry, Maslak, Istanbul, Turkey.
a
fluorimetric
method.
The
rection between H
2
O
2
and
Ce(IV)
ions
is as
follows:
2
Ce
4+
+
H
2
O
2
-> 2
Ce
3+
+ O2 + 2H+
Ce(IV)
is
nonfluorescent
and a
strong oxidizing agent.
Thus determination
of
hydrogen peroxide
is
possible
by
measurement
of the
fluorescence
of the
Ce(III)
pro-
duced.
The fluorescent
species have excitation
and
emis-
sion
maxima
at 260 and 360 nm,
respectively.
EXPERIMENTAL
Apparatus
All
fluorescence
measurements were made with
a
Perkin Elmer
LS 50
luminescence spectrometer
and all
the
spectrophotometric measurements were made with
a
Philips-3700
spectrophotometer.
Reagents
All
chemicals were
of
analytical reagent grade.
Aqueous stock solutions were prepared
using
double-
distilled
(over KMnO
4
) water
as
follows.
Ce(IV)
Solution
(0.01
mol
dm
-3
).
For
this solution
4.043
g of
AnalaR (Merck 2274) eerie
sulfate
was
dis-
solved
in 50 ml of
water containing
10 ml of
concen-
185
1053-0509/98/0600-0185$15.00/0
©
1998
Plenum
Publishing
Corporation

186
Demirata-Ozturk, Ozen, Filik, Tor,
and
Afsar
Fig.
1. (a)
Absorption
spectrum
of 5
|j.mol
of
Ce(IV)
in 10 ml. (b)
Absorption
spectrum
of 5
(imol
of
Ce(III)
in 10 ml. (c)
Emission
spectrum
of a 1 X
10
-4
mol
dm
-3
Ce(III) solution.
Fig.
2.
Change
of fluorescence
with
the
concentration
of
Ce(III).
trated
sulfuric
acid. Then this solution
was
diluted
to 500
ml
with water. This
was
standardized
by the
iodometric
method.
A
calculated quantity
of
this solution
was di-
luted
to 1 L for the
preparation
of the
0.01
mol
dm
-3
Ce(IV) solution.
Ce(III) Solution (0.001
mol
dm-3).
One
hundred
milliliters
of
0.01
mol
dm
-3
Ce(IV)
was
reduced with
hydrogen peroxide
in
acidic medium
and the
unreacted
hydrogen peroxide
was
boiled
away. This solution
was
diluted
to 1 L
with water.
Hydrogen
Peroxide (0.001
mol
dm-3).
Hydrogen
peroxide solution
was
prepared daily
and
standardized
with
permanganate solution
and
used
after
the
desired
dilution.
Recommended Analytical Procedure
Three
and
one-half milliliter
of 1.2 X
10
-4
mol
dm
-3
Ce(IV),
pH
1-2,
was
transferred into
a
Cuvars cell
placed
in the
spectrofluorometer cell compartment
and
it
was
immediately titrated with
10 p1 of a
10
-3
-mol
dm
-3
H
2
O
2
solution. Changes
in the florescence
intensity
of the
solution were measured
at an
excitation
of 260
nm and an
emission
of 360 nm. The
titration
end
point
was
obtained
from
the
plot.
RESULTS
AND
DISCUSSION
Absorption
and
Fluorescence Spectra
The
absorption spectrum
of the
eerie
sulfate
solu-
tion
in 1.0 mol
dm
-3
sulfuric
acid
is
shown
in
Fig.
la.
It
can be
seen that
5
umol
of
eerie
sulfate
in 10 ml of
solution gives
a
maximum absorbance
at 320 nm
against
water.
An
excess amount
of
hydrogen peroxide
was
added
to 5
jmol
of
Ce(IV) solution
in 1.0 mol
dm
-3
sulfuric
acid
and the
mixture
was
diluted
to 10 ml
with
water.
After
the
mixture
was
shaken
for a few
minutes
at
room temperature
the
absorption spectra
of the
solu-
tion were plotted against
a
water blank (Fig. 1b).
The
emission spectrum
of
Ce(III)
is
shown
in
Fig.
1c was
measured
by fixing the
excitation wavelength
at
260 nm. It can be
seen that
the fluorescent
species
of
the
1 X
10
-4
mol
dm=
-3
Ce(III)
solution
has an
emission
maximum
at 360 nm. No fluorescence was
observed
from
the
solution containing Ce(IV) only.
Change
in
Fluorescence with
the
Concentration
of
Ce(III)
The fluorescence of 1 X
10
-5
-l
X
10
-3
mol
dm-
3
Ce(III) solutions
was
measured
at an
excitation
of 260
nm
and an
emission
of 360 nm. A
calibration graph
for
Ce(III)
was
constructed. Good linearity
was
obtained
for
the
concentration range
1 X
10
-5
-2
X
10
-4
mol
dm
-3
Ce(III).
The
curve obtained
is
shown
in
Fig.
2.
Effect
of the
Addition
of
Ce(IV)
to
Ce(III) Solutions
Two
milliliters
of a 1.2 X
10
-3
mol
dm
-3
Ce(III)
solution
was
added
to
each
of 15
volumetric 10-ml

Spectrofluorometric
Determination
of
Hydrogen Peroxide
187
Fig.
3.
Effect
of
Ce(IV)
ions
on
Ce(III)
solution:
Ce(III) concentration
constant
(2.4
X
10
-4
mol
dm
-3
); Ce(IV) concentration
variable.
Fig.
4.
Effect
of
Ce(IV)
on
Ce(III) solution: Ce(IV) concentration
constant
(8 X
10
-5
mol
dm
-3
); Ce(III) concentration variable.
flasks.
After
the
addition
of
Ce(IV) solution
the
mixture
was
diluted
to 10 ml
with water.
If it was
necessary,
before
dilution
the pH of the
solution
was
brought
to
1.0
with concentrated H
2
SO
4
. Final Ce(IV) concentra-
tions
of the
solutions were maintained
at
0.16,0.32,
0.48,
0.64, 0.80, 0.96, 1.12, 1.28,
and
1.44
X
10-4
mol
dm
-3
by the
addition
of
sufficient
amounts
of
Ce(IV)
solution.
The
intensity
of fluorescence of the
solutions
was
measured
at
260/360
nm. The
graph
of fluorescence
intensity versus Ce(IV) concentration
is an
exponential
curve
(Fig.
3).
Figure
3
shows that Ce(IV)
has a
strong
quenching action
on
Ce(III)
ion fluorescence.
The
experiments were repeated with
a
constant con-
centration
of
Ce(IV)
(8 X
10
-5
mol
dm
-3
)
and a
variable
Fig.
5.
Effect
of
Ce(IV) ions
on
Ce(III)
solution: Ce(III)
and
Ce(IV)
concentrations variable.
Ce(III) concentration,
in the
range
of
0.64
X
10
-5
to 9.6
X
10
-5
mol
dm
-3
.
The fluorescence of the
solutions
was
measured
at
260/360
nm
(Fig.
4).
Figure
4
shows that
the
change
in fluorescence
intensity versus Ce(III)
con-
centration
is
linear.
The
experiments were repeated with
a
variable
Ce(III) concentration
in the
range
of 4 X
10
-5
-4
X
10
-4
mol
dm
-3
and a
variable Ce(IV) concentration
in the
range
of 4 X
10
-4
-4
X
10
-5
mol
dm
-3
.
The fluorescence
of the
solutions were measured
at
260/360
nm
(Fig.
5).
Figure
5
shows
that
fluorescence
intensity
versus
Ce(III)
concentration
is an
exponential curve.
Determination
of
Hydrogen Peroxide
Hydrogen peroxide
was
determined according
to
the
recommended
analytical
procedure
by the
titration
technique.
Three
sample titration curves
are
shown
in
Fig.
6. The
standard deviation obtained
in the
replicated
analysis
of
solutions containing hydrogen peroxide
(0.1
ppm)
was
3.5%.
Hydrogen peroxide could also
be
determined
by the
Spectrofluorometric
method. Therefore, between
0.2 and
1.4
ml of
standard hydrogen peroxide solution
(1.17
X
10
-3
mol
dm
-3
)
was
added
to 0.5 ml of
Ce(IV) solution
(1
X
10
-2
mol
dm
-3
)
in a
10-ml
volumetric
flask and
solutions were diluted
to
volume with water.
The fluo-
rescence intensity
of the final
solutions
was
measured
at
260/360
nm. The
change
in fluorescence
intensity
against concentration
of
hydrogen peroxide
was
expo-
nential,
due to the
energy transfer
from
Ce(III)
to
Ce(IV)
(Fig.
7). But the
graph obtained between
the
common

188
Demirata-Oztiirk, Ozen, Filik, Tor,
and
Afsar
Fig.
6.
Spectrofluorometric
titration
of
H
2
O
2
(8.3
X
10
-3
mol
dm
-3
).
(•)
C
Ce(IV)
= 1.5 X 10
-4
mol
dm
-3,
,
concuption
of
H
2
O
2
=
32.5
ul (•)
C
Ce(IV)
= 2.0 X
10
-4
mol
dm
-3
; concuption
of
H
2
0
2
=
40.0 |il.
(±)
C
Ce(IV)
= 2.4 x
10
-4
mol
dm
-3
; concuption
of
H
2
0
2
=
51.0 jil.
Fig.
7.
Change
in fluorescence
intensity with
the
concentration
of hy-
drogen
peroxide:
Ce(IV)
concentration constant
(5 X
10
-4
mol
dm
-3
).
log
of the fluorescence
value
and the
concentration
of
hydrogen peroxide
was
linear. Thus hydrogen peroxide
could
be
determined
by the use of
this graph
as the
cal-
ibration curve.
CONCLUSION
• The
pectrofluorimetric method
has the
basic advan-
tage
of
considerably greater sensitivity than absorp-
tion spectrophotometry.
• No
flurescence
was
observed
from
the
solution
con-
taining Ce(IV) only.
• The
solution contain Ce(III) showed
an
emission band
centered
at 360 nm.
• The
reaction between hydrogen peroxide
and
eerie
ion
proceeds
at a
sufficient
rate
in
acidic medium
and at
room temperature.
• For the
elimination
of
some metal ions such
as
cop-
per(I), lead, tin(II),
and
thallium(I), H
2
SO
4
is
useful
for
acidification [14].
•
Since hydrogen peroxide
has a
high oxidation poten-
tial,
many
of the
reducing ions
are not
present
and
they
do not
interfere with
the
analysis
of
hydrogen
peroxide.
• But
substances having
a
standard potential between
those
of
hydrogen peroxide
and
Ce(IV)
interfere
with
the
analysis.
•
In-addition,
the
proposed method
is
simple
and
rapid.
It
has
been calculated that
the
minimum determination
limit
of the
method
is 0.1 ppm
hydrogen
peroxide.

Spectrofluorometric Determination
of
Hydrogen Peroxide
189
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