chapter-6 section (i) : review on spectrophotometric...
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140
CHAPTER-6
Section (i) : Review on spectrophotometric determination of copper using
hydrazones
Copper is available in nature in the form of sulphides, chlorides and
carbonates. Copper is utilized in electrical industries, electric induction and
industrially useful alloys. It is widely used in printed circuit boards, generators,
transformers, computer heat sinks, coins.
Copper is essential for all plants and animals. It is an essential constituent of
about thirty enzymes and glycoprotein. It is required for the synthesis of hemoglobin
and for some biological process. It is also promotes iron absorption from the
gastrointestinal system. It is involved in the transport of iron from tissues into
plasma.
Though copper is an essential element it becomes hazardous when present in
excess. Excess of copper causes Wilson’s disease. Excess of copper in water is not
only harmful to human beings, but also interferes with the self purification of bulk
water and exerts an adverse effect on the microbiological treatment of waste water.
Too much copper in water has also been found to damage marine life.
A vast number of organic reagents were reported1-48
for the spectrophotometric
determination of the copper(II) ion. The author has therefore not ventured to describe
all these reagents in view of the fact that good reference books49,50
are available on
this topic. A review on spectrophotometric determination of copper(II) using organic
reagents are presented in Table 6.(i).1.
141
141 -143 ; Tables
142
143
144
Section (ii): Spectrophotometric determination of Cu(II) using salicylaldehyde
acetoylhydrazone(SAAH)
Yellow coloured solution was formed instantaneously when salicylaldehyde
acetoylhydrazone (SAAH) was added to Cu(II) taken in sodium acetate – acetic acid
buffer solution. This colour reaction was investigated in detail and developed a
spectrophotometric method for the determination of Cu(II) in aqueous medium.
a. Absorption spectra of SAAH and its copper (II) Complex
The absorption spectra of the solution containing Cu(II) – SAAH complex
against reagent blank and that of SAAH solution against water blank were recorded at
pH 5.0 by employing the procedure described in 2 iv.a in 250 – 600 nm wavelength
range. Typical spectra are presented in Fig. 6.ii.a. The spectra indicate that the Cu(II)
complex shows broad peak with maximum absorption at 372 nm where the reagent
blank has less absorbance. Hence, the wavelength 372 nm was chosen for further
studies.
b. Effect of pH on the absorbance of Cu(II) complex
The effect of pH on the colour intensity of the Cu(II) – SAAH complex was
studied and the optimum pH was established by adopting the procedure given in
2.iv.b. The graph (Fig. 6.ii.b) indicates that the complex shows maximum and
constant absorbance in the pH range 4.5 – 5.5. Hence, pH 5.0 is chosen for
subsequent studies.
145
Fig: 6.ii.a. Absorbance Spectra of
a. Cu(II) – SAAH complex Vs SAAH Solution
b. SAAH Vs Water blank
[Cu(II)] = 2.0 × 10-5
M
[SAAH ] = 4.0 × 10-4
M
pH = 5.0
DMF = 10%(V/V)
340 360 380 400 420 440 460 480 500
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
a
b
Ab
so
rba
nce
Wavelength (nm)
146
Fig: 6.ii.b. Effect of pH on the absorbance of Cu(II) – SAAH complex
[Cu(II)] = 6.0 × 10-5
M
[SAAH ] = 4.0 × 10-4
M
Wavelength(λ) = 372 nm
DMF = 10%(V/V)
c. Effect of reagent concentration on the absorbance of the complex
1 2 3 4 5 6 7 8 9 10
0.45
0.50
0.55
0.60
0.65
0.70
0.75
Ab
so
rba
nce
pH
147
The amount of reagent necessary for full colour development was established
by the following the procedure in 2.iv.c. The results are presented in Table 6.ii.1.
Table 6.ii.1
Effect of SAAH concentration on the absorbance of Cu(II) complex
[Cu(II)] = 4 × 10–5
M
pH = 5.0
Wavelength (λ) = 372nm
Cu(II) : SAAH Absorbance
1 : 05 0.360
1 : 10 0.393
1 : 20 0.405
1 : 40 0.410
1 : 60 0.464
1 : 80 0.475
The data in Table 6.ii.1 indicate that a 10–fold molar excess of reagent is
sufficient for full colour development. Therefore, further studies were carried out
using 10–fold molar excess of reagent to Cu(II).
d. Effect of time on the absorbance of Cu(II) complex
The absorbance of Cu(II) – SAAH complex was measured at different time
intervals to ascertain the time stability of the complex as described in 2.iv.d. The
absorbance of the Cu(II) complex was measured at 372 nm. The concentration of
[SAAH] and [Cu(II)] were 4 × 10–4
M and 4 × 10–5
M respectively. The colour
development is instantaneous and remains constant for more than 2 hour.
e. Effect of the order of addition of constituents
148
The order of addition of constituents (buffer, copper ion and reagent) has no
adverse effect on the absorbance of the Cu(II) – SAAH complex.
f. Applicability of Beer’s law
To examine the applicability of Beer’s law for the present system, the
procedure given in 2.iv.f was adopted. A linear plot between absorbance and amount
of Cu(II) is shown in Fig. 6.ii.c. The straight line obeys the equation A372 = 0.0606C
+ 0.0069. Further, the calibration of graph suggests that the system obeys Beer’s law
in the range of 1.0 – 9.0 µg/ml of Cu(II). The molar absorptivity and Sandell’s
sensitivity are 1.0 × 104 lit mol
-lcm
-1 and 0.635 µg cm
–2 of Cu(II) respectively. The
specific absorptivity of the system is found to be 0.157 ml g-1
cm-1
. The standard
deviation for ten determinations of 1.90 µg/ml of Cu(II) is 0.0059. The relative
standard deviation and mean absorbance are 1.75% and 0.338 ± 0.0006 respectively.
g. Tolerance limits of foreign ions
The effect of foreign ion was studied with a view to examine the applicability
of the method in presence of foreign ions. Interference of various ions was studied
with 1.90 µg/ml of copper by adopting the procedure given in 2.iv.g. The tolerance
limit value was taken as the amount of foreign ion required to cause ± 2% error in the
absorbance of Cu(II) – SAAH complex. The tolerance limit values for foreign ions
are presented in Table 6.ii.2.
149
Fig. 6.ii.c : Calibration plot for Cu(II) determination
pH = 5.0
[SAAH] = 4 × 10–4
M
Wavelength(λ) = 372 nm
DMF = 10%(V/V)
0 1 2 3 4 5 6 7 8 9 10 11
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
A372
= 0.0606C + 0.0069A
bso
rba
nce
Amount of Cu(II) (µg/ml)
150
Table 6.ii.2
Tolerance limit of foreign ions in the determination of 1.90 µg/ml of Copper
Ion added Tolerance limit
µg/ml Ion added
Tolerance limit
µg/ml
Tartrate 254 Ag(I) 13
Hypo 254 Ni(II) 5.0
Nitrate 254 Fe(II) 4.0
Sulphate 254 Mn(II) 2.5
Thiourea 254 Co(II) 2.5
Urea 203 Fe(III) 2.5a
Fluoride 178 Zn(II) 2.5
Phosphate 127 Pb(II) 2.8
Iodide 127 Fe(II) 2.8
Chloride 50.8 Mo(II) 2.5
Bromide 25.4 Hg(II) 2.0b
Oxalate 2.3 Sn(IV) 2.0
EDTA 0.5 Pd (II) 1.5
Citrate 0.5
aMasked with 200 µg/ ml of iodide.
bMasked with 250 µg/ ml of cyanide.
h. Applications
The amount of copper present in synthetic sample whose composition
corresponding to BAS – 106, Monel metal were determined by using the procedure
given in chapter 2.iv.h. Data are given in Table 6.ii.3.
Table 6.ii.3
Sample Percentage of Copper*
Error Certified value Found value
BAS – 106a 4.10 4.12 0.02%
Monel metalb 30.00 30.15 0.15%
* Average of three determinations
a = BAS – 106 : Ni 1.93%, Cu 4.1%, Fe 0.43%, Mn 0.2% and Mg 1.61% b. = Monel metal : Cu 30%, Ni 67%, Fe 3%
151
i. Composition and stability constant of Cu(II) – SAAH complex
Job’s continuous variation and molar ratio methods are employed to determine
the composition of the complex. The stability constant of the complex was calculated
using the data obtained in the Job’s plot.
a. Job’s continuous variation method
The procedure given in 2.iv.i.a was used in this method. A graph is prepared
between the mole fraction of reagent and absorbance. Job’s plot (Fig. 6.ii.d) indicates
that 1 mole of reagent react with one mole of the metal ion. Therefore, the
composition of the complex in solution is 1 : 1 (M : L). The data obtained in the Job’s
curve are used in the calculation of stability constant of the complex. The stability
constant of the 1 : 1 complex was calculated by using the following equation
C
) - (1 β
21 : 1α
α=
Where
α = degree of dissociation constant (0.06)
C = Concentration of ligand corresponding to intersection point (7.2 × 10-5
M).
By using the values of α and C obtained in Job’s method, the stability constant
is calculated as 3.76 × 104.
152
Fig. 6.ii.d : Job’s Curve
Cu(II) = SAAH = 4 × 10–4
M (Stock solution)
Wavelength (λ) = 372 nm
pH = 5.0
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
Ab
so
rba
nce
Molefraction of reagent
153
Fig. 6.ii.e : Molar ratio plot
Cu(II) = 4 × 10–4
M (Stock solution)
Wavelength(λ) = 372 nm
pH = 5.0
0.00 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 2.25 2.50 2.75
0.1
0.2
0.3
0.4
0.5
0.6
0.7
Ab
so
rba
nce
Mole of reagent per mole of metal ion
154
b. Molar ratio method
The molar ratio plot (Fig. 6.ii.e) gives the composition of the complex as 1 : 1
[Cu : SAAH]. Thus, molar ratio method supports the composition of the complex
obtained in Job’s method.
Based on the composition of the complex the following structure is tentatively
assigned for the complex.
Structure of Cu – SAAH complex
Summary
Salicylaldehyde acetoylhydrazone (SAAH) forms a pale yellow coloured
species with Cu(II) in acid medium. The important physico-chemical and analytical
characteristics of the Cu(II) –SAAH system are summarized in Table 6.ii.4.
155
Table 6.ii.4
Physico – chemical and analytical characteristics of Cu(II) – SAAH complex
S. No. Characteristics Results
1 λmax (nm) 372
2 pH range (optimum) 4.5 – 5.5
3 Mole of reagent required per mole of
metal ion for full colour development 10 fold
4 Time stability of the complex (in hrs) 2
5 Beer's law validity range (µg/ml) 1.0 – 9.0
6 Molar absorptivity (lit mol-1
cm-1
) 1.0 × 104
7 Specific absorptivity (ml g-1
cm-1
) 0.157
8 Sandell’s sensitivity µg of Cu(II) cm-2
0.635
9 Composition of the complex as
obtained in Job's and molar ratio
methods (M : L)
1 : 1
10 Stability constant of the complex 3.76 × 104
11 Mean absorbance 0.234 ± 0.0002
12 Standard deviation in the
determination of 1.90 µg/ml of Cu(II)
for ten determinations
0.0061
13 Relative Standard deviation (RSD) % 2.60
14 Y–intercept 0.0069
15 Angular coefficient 0.0606
16 Detection limit (µg/ml) 0.0782
17 Determination limit (µg/ml) 0.2346
156
Section (iii): Spectrophotometric determination of Cu(II) using 2,4–dihydroxy
acetophenone acetoylhydrazone(DAAH)
Yellow coloured solution was formed instantaneously when 2,4–dihydroxy
acetophenone acetoylhydrazone (DAAH) was added to Cu(II) taken in sodium acetate
– acetic acid buffer solution. This colour reaction was investigated in detail and
developed a spectrophotometric method for the determination of Cu(II) in aqueous
medium.
a. Absorption spectra of DAAH and its copper(II) Complex
The absorption spectra of the solution containing Cu(II) – DAAH complex
against reagent blank and that of DAAH solution against water blank were recorded at
pH 4.0 by employing the procedure described in 2 iv.a in 250 – 600 nm wavelength
range. Spectra in Fig. 6.iii.a indicate that the Cu(II) complex shows broad peak with
maximum absorption at 370 nm where the reagent blank has less absorbance. Hence,
the wavelength 370 nm was chosen for further studies.
b. Effect of pH on the absorbance of Cu(II) complex
The effect of pH on the colour intensity of the Cu(II) – DAAH complex was
studied and the optimum pH was established by adopting the procedure given in
2.iv.b and the results are presented in Fig. 6.iii.b. The graph indicates that the
complex shows maximum and constant absorbance in the pH range 3.0 – 4.5. Hence,
pH 4.0 is chosen for subsequent studies.
157
Fig: 6.iii.a. Absorbance Spectra of
a. Cu(II) – DAAH complex Vs DAAH Solution
b. DAAH Vs Water blank
[Cu(II)] = 2.0 × 10-5
M
[DAAH ] = 4.0 × 10-4
M
pH = 5.0
DMF = 10%(V/V)
340 360 380 400 420 440 460 480 500
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
a
b
Ab
so
rba
nce
Wavelength (nm)
158
Fig: 6.iii.b. Effect of pH on the absorbance of Cu(II) – DAAH complex
[Cu(II)] = 4.0 × 10-5
M
[DAAH ] = 4.0 × 10-4
M
Wavelength(λ) = 370 nm
DMF = 10%(V/V)
2 3 4 5 6 7
0.20
0.22
0.24
0.26
0.28
0.30
0.32
0.34
0.36
0.38
0.40
Ab
so
rba
nce
pH
159
c. Effect of reagent concentration on the absorbance of the complex
The amount of reagent necessary for full colour development was established
by following the procedure in 2.iv.c. The results are presented in Table 6.iii.1.
Table 6.iii.1
Effect of DAAH concentration on the absorbance of Cu(II) complex
[Cu(II)] = 4 × 10–5
M
pH = 4.0
Wavelength (λ) = 370 nm
Cu(II) : DAAH Absorbance
1 : 05 0.460
1 : 10 0.470
1 : 20 0.484
1 : 40 0.492
1 : 60 0.500
The data in Table 6.iii.1 indicate that a 5–fold molar excess of reagent is
sufficient for full colour development. Therefore, further studies were carried out
using 5–fold molar excess of reagent to Cu(II).
d. Effect of time on the absorbance of Cu(II) complex
The absorbance of Cu(II) – DAAH complex was measured at different time
intervals to ascertain the time stability of the complex as described in 2.iv.d. The
absorbance of the Cu(II) complex was measured at 370 nm. The concentration of
[DAAH] and [Cu(II)] were 4 × 10–4
M and 4 × 10–5
M respectively. The colour
development is instantaneous and remains constant for 2 hours.
160
e. Effect of the order of addition of constituents
The order of addition of constituents (buffer, metal ion and reagent) has no
adverse effect on the absorbance of the Cu(II) – DAAH complex.
f. Applicability of Beer’s law
To examine the applicability of Beer’s law for the present system, the
procedure given in 2.iv.f was adopted. A linear plot between absorbance and amount
of Cu(II) is shown in Fig. 6.iii.c. The straight line obeys the equation A370 = 0.2956C
+ 0.0057. Further, the calibration of graph suggests that the system obeys Beer’s law
in the range of 0.2 – 2.0 µg/ml of Cu(II). The molar absorptivity and Sandell’s
sensitivity are 1.02 × 104 lit mol
-lcm
-1 and 0.623 µg cm
–2 of Cu(II) respectively. The
specific absorptivity of the system is found to be 0.160 ml g-1
cm-1
. The standard
deviation for ten determinations of 1.27 µg/ml of Cu(II) is 0.0070. The relative
standard deviation is 3.04%.
g. Tolerance limits of foreign ions
The effect of foreign ion was studied with a view to examine the applicability
of the method in presence of foreign ions. Interference of various ions was studied
with 1.27 µg/ml of copper by adopting the procedure given in 2.iv.g. The tolerance
limit value was taken as the amount of foreign ion required to cause ± 2% error in the
absorbance of Cu(II) – DAAH complex. The tolerance limit values for foreign ions
are presented in Table 6.iii.2.
161
Fig. 6.iii.c : Calibration plot for Cu(II) determination
pH = 4.0
[DAAH] = 4 × 10–4
M
Wavelength(λ) = 370 nm
DMF = 10%(V/V)
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2
0.0
0.1
0.2
0.3
0.4
0.5
0.6 A370
= 0.2956C+ 0.0057A
bso
rba
nce
Amount of Cu(II) (µg/ml)
162
Table 6.iii.2
Tolerance limit of foreign ions in the determination of 1.27 µg/ml of Copper
Ion added Tolerance limit
µg/ml Ion added
Tolerance limit
µg/ml
Edta 15 Mg(II) 28
Tartrate 592 Zn(II) 26
Citrate 326 Ni(II) 24
Sulphate 307 Mn(II) 22
Iodide 252 Mo(II) 19
Bromide 240 Fe(II) 11
Thiourea 152 Hg(II) 8a
Chloride 142 Co(II) 2.3
Nitrate 124 Ag(I) 2.2
Fluoride 76 Cu(II) 1.9
Phosphate 30 Al(III) 0.5
Oxalate 18 Fe(III) 0.4b
a Masked with 200 µg/ ml of iodide.
b
Masked with 450 µg/ ml of cyanide.
h. Applications
The amount of copper present in synthetic sample whose composition
corresponding to BAS – 106, monel metal were determined by using the procedure
given in chapter 2.iv.h. Data is given in Table 6.iii.3.
Table 6.iii.3
Sample Percentage of Copper*
Error Certified value Found value
BAS – 106a 4.10 4.13 0.03%
Monel metalb 30.00 30.07 0.07%
* Average of three determinations
a = BAS – 106 : Ni 1.93%, Cu 4.1%, Fe 0.43%, Mn 0.2% and Mg 1.61%
b. = Monel metal : Cu 30%, Ni 67%, Fe 3%
163
i. Composition and stability constant of Cu(II) – DAAH complex
Job’s continuous variation and molar ratio methods are employed to determine
the composition of the complex. The stability constant of the complex was calculated
using the data obtained in the Job’s plot.
a. Job’s continuous variation method
The procedure given in 2.iv.i.a was used in this method. A graph is prepared
between the molefraction of reagent and absorbance. Job’s plot (Fig. 6.iii.d) indicates
that 1 mole of reagent DAAH reacts with one mole of the Cu(II) ion. Therefore, the
composition of the complex in solution is 1 : 1 (M : L). The data obtained in the Job’s
curve are used in the calculation of stability constant of the complex. The stability
constant of the 1 : 1 complex was calculated using the following equation
C
) - (1 β
21 : 1α
α=
Where
α = degree of dissociation constant (0.031)
C = Concentration of ligand corresponding to intersection point (1.0 × 10–4
M).
The stability constant of the complex is calculated by using α (0.031) and C
(1.0 × 10–4
) values obtained in Job’s method. The stability constant is calculated as
1.08 × 105.
164
Fig. 6.iii.d : Job’s Curve
Cu(II) = DAAH = 5 × 10–4
M (Stock solution)
Wavelength (λ) = 370 nm
pH = 4.0
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
Ab
so
rba
nce
Mole fraction of ligand
165
Fig. 6.iii.e : Molar ratio plot
Cu(II) = 5 × 10–4
M (Stock solution)
Wavelength (λ) = 370 nm
pH = 4.0
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
Ab
so
rba
nce
Mole of reagent per mole of metal ion
166
b. Molar ratio method
The molar ratio plot (Fig. 6.iii.e) gives the composition of the complex as 1 : 1
[Cu : DAAH]. Thus, molar ratio method supports the composition of the complex
obtained in Job’s method.
Based on the composition of the complex following structure is tentatively
assigned for the complex.
Structure of Cu – DAAH complex
Summary
2,4–Dihydroxyacetophenone acetoylhydrazone (DAAH) forms an yellow
coloured species with Cu(II) in acid medium. The colour reaction between Cu(II) and
DAAH is almost instantaneous and the absorbance of complex remains constant for 2
hour. The order of addition of constituents [buffer, Cu(II) ion and DAAH] has no
adverse effect. The important physico-chemical and analytical characteristics of the
[Cu(II) –DAAH] complex are summarized in Table 6.iii.4.
167
Table 6.iii.4
Physico – chemical and analytical characteristics of Cu(II) – DAAH complex
S. No. Characteristics Results
1 λmax (nm) 370
2 pH range (optimum) 3.0 – 4.5
3
Mole of reagent required per mole of metal
ion for full colour development
5 fold
4 Time stability of the complex (in hrs) 2
5 Beer's law validity range (µg/ml) 0.2 – 2.0
6 Molar absorptivity (lit mol-1
cm-1
) 1.02 × 104
7 Specific absorptivity (ml g-1
cm-1
) 0.160
8 Sandell’s sensitivity µg of Cu(II) cm-2
0.623
9
Composition of the complex as obtained in
Job's and molar ratio methods
1 : 1
10 Stability constant of the complex 1.08 × 105
11 Mean absorbance 0.230 ± 0.0005
12 Standard deviation in the determination of
1.27 µg/ml of Cu(II) for ten determinations 0.0059
13 Relative Standard deviation (RSD) % 1.75
14 Y–intercept 0.0057
15 Angular coefficient 0.5912
16 Detection limit (µg/ml) 0.0523
17 Determination limit (µg/ml) 0.156
Section (iv): A comparative account of physico – chemical and analytical
168
characteristics of Cu(II) complexes with SAAH and DAAH
The colour reactions between Cu(II) and the reagents are instantaneous.
Absorbance of both complexes remain constant for a period of 2 hrs. In SAAH
method 10–fold molar excess of reagent while in DAAH method only 5 fold molar
excess of reagent is required for full colour development.
Spectrophotometric method using DAAH is more sensitive when compared
with method using SAAH. Both SAAH and DAAH form 1 : 1 (M : L) complex with
Cu(II). Cu–DAAH complex is more stable when compared with Cu – SAAH
complex. Further the tolerance limit values of DAAH method suggest that the reagent
is more selective for Cu(II) and it may be due to its ability to form more stable
complex (β = 1.08 × 105) with Cu(II). Other physico–chemical and analytical
properties of complexes are compared in Table 6.iv.1.
169
Table 6.iv.1
Comparative account on physico-chemical and analytical properties of Cu (II)
complexes with SAAH and DAAH
S.
No. Characteristics Cu–SAAH Cu–DAAH
1 λmax (nm) 372 370
2 pH range (optimum) 4.5 – 5.5 3.0 – 4.5
3 Mole of reagent required per mole of
metal ion for full colour development 10 fold 5 fold
4 Time stability of the complex (in hrs) 2 2
5 Beer's law validity range (µg/ml) 1.0 – 9.0 0.2 – 2.0
6 Molar absorptivity (lit mol-1
cm-1
) 1.00 × 104 1.02 × 10
4
7 Specific absorptivity (ml g-1
cm-1
) 0.157 0.160
8 Sandell’s sensitivity µg of Cu(II) cm-2
0.635 0.623
9
Composition of the complex as
obtained in Job's and molar ratio
methods
1 : 1 1 : 1
10
Stability constant of the complex 3.76 × 10
4 1.08 × 10
5
11 Mean absorbance 0.234 ± 0.0002 0.230 ± 0.0005
12 Standard deviation of Cu(II) for ten
determinations 0.0061* 0.0059**
13 Relative Standard deviation (RSD) % 2.60 1.75
14 Y–intercept 0.0069 0.0057
15 Angular coefficient 0.0606 0.5912
16 Detection limit (µg/ml) 0.0782 0.0523
17 Determination limit (µg/ml) 0.2346 0.156
* In the determination of 1.90 ppm of Cu(II)
* In the determination of 1.27 ppm of Cu(II)
170
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Table No. 6.i.1
Spectrophotometric methods for the determination of Copper (II) with different
reagents
Reagent λmax (nm) pH/
medium
ε
(L mol-1
cm-1
)
Aqueous/
Extraction
Beer's law
range Ref.
Eriochrome Blue Black-R - - 1.3 x 104 - 0-23 ppm 51
1 -(o-Carboxyphenyl)-3-benzoyl-5-phenyl
formazone 500 4.1 1.42 x l0
4 - 0.00-5.08 52
N-p-Nitro-(2-mercapto)propionalide on
micro crystalline naphthalene 450 3.0-3.5 - - - 53
2-(-2'-(6'-Methyl-benzothiozolyl)azo)-5-
dimethyl amino benzoic acid 660 2.0-5.0 7.0 x l0
4 -
0.0-0.72
µg/ml 54
2-(2-(4-Methylbenzothiozolyl)azo-5-
dimethylamino benzoic acid (4-Me-
BTAMB)
650 3.1 x104 - 0.04-2 µg 55
Cetyl trimethyl ammoniumbromide in
presence of iodide - 0.5-3.5 1.0 x l0
4 CHC13
Up to 10
ppm 56
(2-Thioorotic acid (6-hydroxy-2-mercapto
pyrimidine-2-carboxylic acid) - 7 1.04 x 10
2 Pyridine - 57
3-Hydroxypicolinoamide few aliphatic and
aromatic acids - - - - - 58
Cupron in the presence of Brij 35 445 8 6.6 x 104 - Up to 7 ppm 59
Thenoyltrifluoro acetone (TTA) assocd - 7.5 - - 0-8 mg 60
Alizarin red 5 (ARS) sensitized by borate 526 8.5 1.77 x l04 - - 61
2-Hydroxy-4-n-butoxyacetophenoneoxime 370, 650 - 1.08 x 104 - 327 µg/ml 62
Potassium salt of 4-methyl piperidine
dithiocarbamic acid - - 1.78 x l0
4 Ch10roform 0.0-20.0 63
141
176
Reagent λmax nm pH/
medium
ε
L mol-1
cm-1
Beer’s law
range
Aqueous/
Extraction Ref.
8-Methoxy-2-ch10roquinoline-3-
carbaldehyde thiosemicarbazone 410 5 2-67 x10
3
Up to 3
ppm - 64
Poly(allylamine-(0-N-4-(8-aminoquinolyl-5-
azo)benzylidene allylamine] (PA-FDq) 590
Alkaline
media 4.1 x 10
4 0-l.0 µg/ml - 65
l-[2-Butylthio-4-methyl-6-
pyrimidinylthio)acetyl]-4-phenyl
thiosemicarbazide
- - - - - 66
1 ,5-diaryl-3-cyanoformazan - - - 3-18mg/cm3 - 67
1 ,3 ,4-Thiodiazole-2,5-dithiol 350 KH2PO4 and
NaOH ` 4-5 ppm - 68
Potassium Py Xanthate (KPx) 400 6 - 1.16 µg/ml
Methyl
isobutyl
ketone
69
3-Methyl-2-benzothiozolinone hydrazone
with N-ethyl-N-(2-hydroxy-3-sulfo-propyl)-
3,5-dimethyoxyaniline (Produe re)
525 - – 0.002-0.1
mg / cm3
Presence
ofH2O2 70
Bis(acetylacetone)ethylenediimine 545 - - Up to 20
µg/ml CHC13 71
Benzyoyl formazone 9.25 1.2 x104 - - 72
N-(2,5-Dimethylphenyl)-p-toluimidoyl
phenyl hydrazine - - - - - 73
Bis (2,4,4-trimethyl pentyl)-
dithiophosphinic acid (Cyanex 301) 440 0.5 N HC1 5.0 × l0
4 - - 74
2-Hydroxy-4-n-butoxy-5 -
nitroacetophenone oxime 410 1.6 x 10
4 - CHC13 75
142
177
Reagent λmax nm pH/
medium
ε
L mol-1
cm-1
Beer's law
range
Aqueous/
Extraction Ref.
N-(2,5-Dimethylphenyl)-p-toluimidoyl
phenyl hydrazine 410 7.0-10.5 4.0 × l0
4 - - 76
2,4-Dihydroxy benzaldehyde
isonicotinoylhydrazone 430 2 1.65 × l0
4
0.063-2.55
µg/ml - 77
1 ,4-Dihydrazonopthalazine 380 0.1-1MHC1 2.2 x 103
0-54µg
/25ml 78
Chrome Azurol S 583.5 5-6 1.1 x 103 0-5 - 79
Rhodamine 4G oxidized by KIO3 in
presence of surfactant 546 - -
0-3.5
µg/25ml - 80
5-Cl-PADAB-TritonX-100 520 6.5 4.6 x 103 0-1.12 - 81
5-[4'-(3'-Pyridinium propoxy) phenyl]-
10,15,20-triphenyl porphyrin bromide 413 - 2.9 x l0
5
0-
0.6µg/10ml - 82
2-Acetyl-4-phenyl-3-thiosemicarbazone 385 3-6 2.92 x 103 0.10-0.51 - 83
1 -Phenyl- l,2-propanedione-2-
oximethiosemicarbazone 465 5 5.56 × 10
3 0.38-7.63 - 84
a-Benzoin oxime in Triton-X-100 - - 5.7 × l03 - - 85
Phosphoryl derivative of p-tetra-
butylthiacalix(4)arene - 8.3 1.0 × 10
3 - - 86
143