Novel dithiocarbamates for electrochemical detection of nickel(II) in environmental samples

Article abstract of DOI:10.14233/ajchem.2015.18883

Ammonium 4-phenylpiperazine-1-dithiocarbamate (Amm 4-PP-DTC) and ammonium 4-benzylpiperidine-1-dithiocarbamate (Amm 4-BP-DTC) were synthesized for the determination of nickel(II) using catalytic hydrogen currents (CHC's) technique with DC Polarography. Th

Full text of DOI:10.14233/ajchem.2015.18883

Asian Journal of Chemistry; Vol. 27, No. 10 (2015), 3598-3604
A
SIAN
J
OURNAL OF HEMISTRY
C
http://dx.doi.org/10.14233/ajchem.2015.18883
Novel Dithiocarbamates for Electrochemical Detection of Nickel(II) in Environmental Samples
1
2
2
1,*
T. NIRANJAN , SUVARDHAN KANCHI , KRISHNA BISETTY and N. VENKATASUBBA NAIDU
1
2
Department of Chemistry, Sri Venkateswara University, Tirupati-517 502, India
Department of Chemistry, Durban University of Technology, Durban 4000, South Africa
*
Corresponding author: E-mail: nvsn69@gmail.com
Received: 27 November 2014; Accepted: 2 February 2015;
Published online: 22 June 2015;
AJC-17310
Ammonium 4-phenylpiperazine-1-dithiocarbamate (Amm 4-PP-DTC) and ammonium 4-benzylpiperidine-1-dithiocarbamate (Amm 4-
BP-DTC) were synthesized for the determination of nickel(II) using catalytic hydrogen currents (CHC’s) technique with DC Polarography.
The method was based on the chelation of nickel(II) with Amm 4-PP-DTC/ Amm 4-BP-DTC in presence of NH
catalytic hydrogen current at -1.50V and -1.41 V vs. SCE respectively. Optimized polarographic conditions were established by studying
effect of pH, supporting electrolyte (NH Cl), ligands and metal ion concentration and effect of adverse ions on peak height to improve the
4
OH at pH 6.8 to produce
4
sensitivity, selectivity and detection limits of the present method. This technique is successfully applied for the analysis of nickel(II) in
different matrices with recoveries ranging from 96.0-99.0 % and the results obtained were comparable with the atomic absorption
spectroscopy.
Keywords: DC polarography, Catalytic hydrogen current technique, Nickel(II),Ammonium 4-arylpiperazine-1-dithiocarbamate.
average levels of Ni(II) occur in foods because of contami-
nation during processing and cooking in nickel-plated utensils.
Therefore, it is important to develop sensitive, rapid and
economical method for the quantitative determination of
trace amounts of nickel in various samples of environmental
INTRODUCTION
Nickel is a naturally occurring, lustrous, silvery-white
metallic element. It is mainly available in gernirite, magnesium
nickel silicate of different composition in the form of ores.
Nickel is an important element, because it forms alloys with
several other elements and also useful in making corrosive-
resistant alloys such as Monel, Inconel and the Hastelloys.
Nickel plating is often used to coat other metals for protection and
used in the manufacture of ceramics, Edison storage battery.
The absorption of nickel is dependent on its physico-chemical
form, with water soluble forms being more readily absorbed.
The metabolism of nickel involves conversion to various
7-10
importance. Several analytical techniques such asAAS , ICP-
1
1-13
14,15
AES
and XRF
for the determination of nickel was
reviewed. However, electrochemical instrumentation is compa-
ratively economical, sensitive and selective for the analysis of
Ni(II) in trace and ultra-trace levels in various environmental
and agricultural samples. Catalytic hydrogen current’s tech-
nique was earlier developed in our laboratory for the deter-
mination of Ni(II) in drinking water samples and agricultural
1
16-19
chemical forms and binding to various ligands . Nickel in large
samples using D.C. Polarography
.
dose (< 0.5 g), some forms of nickel may be acutely toxic to
The preliminary work on polarographic behaviour of
Ni(II) with ammonium 4-phenylpiperazine-1-dithiocarbamate
(Amm 4-PP-DTC) and ammonium 4-benzylpiperidine-1-
dithiocarbamate (Amm 4-BP-DTC) in ammonium chloride-
ammonium hydroxide medium revealed that a nickel reduction
wave is followed by a catalytic wave. Dithiocarbamates (Amm
4-PP-DTC and Amm 4-BP-DTC) or simple metal ions in the
medium do not give any peak current at the potentials of
catalytic hydrogen current’s (CHC; -1.50V and -1.41V vs. SCE)
and the current-voltage curves of Ni(II)-dithiocarbamate comp-
lexes are shown in the Fig. 1a and 1b.
2,3
human when taken orally . The toxic effect of oral exposure
to nickel usually involve the kidney defects with some evidence
form animals studies showing a possible developmental/
1,4
reproductive toxicity effect . Even though nickel is moderately
toxic, still low concentration effects on human system causing
5
dermatological, lung disease and malignant tumours . Mainly
nickel enters into water system from the industrial processes
6
and waste disposals .According to U.S. Public Health Service,
the average concentration of nickel in domestic water is 4.8
µg/L and the daily intake is about 0.3 to 0.6 mg/day. Higher

Vol. 27, No. 10 (2015)
Novel Dithiocarbamates for Electrochemical Detection of Nickel(II) in Environmental Samples 3599
currents are studied using D.C. recording polarograph model
CL-25 of Elico Pvt. Ltd., Hyderabad, India. The Shimadzu
AA 6300 spectrometer equipped with a hollow cathode lamp
and a deuterium background corrector, at respective wave-
lengths (resonance line) using an air acetylene flame was used.
The instrumental parameters were those recommended by the
manufacturer.
All reagents were of analytical grade and deionized double
distilled water was used for the preparation of all solutions.
1
-Phenylpiperazine, 4-benzylpiperidine, carbon disulphide,
(d)
ammonium chloride and ammonia solution were purchased
from S.D. Fine chemicals, Mumbai, India. Standard solution
of Ni(II) (1 µg/mL) was prepared by weighing 4.050 g of
NiCl
2
·6H O (S.D. Fine chemicals, Mumbai, India) and
2
(
c)
dissolved in deionized double distilled water and made up to
the mark in 1 L standard flask. Amm 4-PP-DTC (0.01 M) was
prepared by weighing 2.55 g ofAmm 4-PP-DTC and dissolved
in 100 mL deionized double distilled water. Amm 4-BP-DTC
(b)
(
0.01 M) was prepared by weighing 2.67 g of Amm 4-BP-
(a)
DTC and dissolved in 100 mL deionized double distilled water.
Freshly prepared solution was stored in dark coloured bottle.
Stock solutions of Amm 4-PP-DTC, Amm 4-BP-DTC and
1.3
1.4
1.5
1.6
1.7
–
V vs. SCE
NH Cl were prepared by appropriate dilutions in 250 mL
standard flask and stored in dark place.
Synthesis of Amm 4-PP-DTC and Amm 4-BP-DTC:
Carbon disulphide (40 g) was slowly added to a solution of
4
Fig. 1a. Polarographic curve of Ni(II) in NH
presence of Amm 4-PP-DTC (a)0.3 M NH
mM Amm 4-PP-DTC (c) a+3.0 ppm Ni(II) (d) b+3.0 ppm Ni(II)
4
Cl-NH
4
OH medium in the
4
Cl, pH~6.8 (b) a+3.6
1
-phenylpiperazine/4-benzylpiperidine (45 g) in 25 mL of
deionized double distilled water at 5 °C with constant stirring,
followed by ammonium hydroxide. The product (Schemes I
and II) was warmed to room temperature and washed repeatedly
two to three times with purified acetone. The reaction product
2
0-26
was purified by recrystallization in acetone . The purified
compounds have melting points of 194-199 °C (Amm 4-PP-
DTC) and 207-213 °C (Amm 4-PP-DTC) at 740 mm pressure.
(d)
S
NH OH
+
CS
2
4
N
N
N
5 o
C
-
+
S NH
4
(c)
N
H
Amm 4-PP-DTC
1-Phenylpipierazine
(b)
Scheme-I: Synthesis of Amm 4-PP-DTC
(
a)
S
-
N
1.2
1.3
1.4
1.5
1.6
+
SNH
NH OH
5 oC
4
4
–
V vs. SCE
+
CS2
Fig. 1b. Polarographic curve of Ni(II) in NH
4
Cl-NH
4
OH medium in the
presence of Amm 4-BP-DTC (a) 0.4 M NH
mM Amm 4-BP-DTC (c) a+3.0 ppm Ni(II) (d) b+3.0 ppm Ni(II)
4
Cl, pH~6.8 (b) a+3.8
Amm 4-BP-DTC
N
H
4
-Benzylpiperidine
EXPERIMENTAL
Scheme-II: Synthesis of Amm 4-BP-DTC
The current-voltage curves are recorded using a DC
polarographic analyzer, model CL-357 coupled with model
LR-101 strip chart recorder manufactured by Elico Private Ltd.
General procedure: A measured volume of the NH Cl,
supporting electrolyte and ligands (Amm 4-PP-DTC andAmm
4-BP-DTC) were added to the electro-active species [Ni(II)],
4
(Hyderabad, India). Effects of mercury height on polarographic

3
600 Niranjan et al.
Asian J. Chem.
3
2
2
1
0
5
0
5
maintaining the optimum pH and the solution was made up to
00 mL in a standard flask with deionized double distilled water
and then transferred to the polarographic cell. The dissolved
oxygen was expelled by bubbling pure nitrogen through the
analyte solution for 15 min. Polarograms of the solutions were
recorded using DC Polarography.
Amm 4-PP-DTC
Amm 4-BP-DTC
1
RESULTS AND DISCUSSION
Various optimal conditions developed for the determi-
nation of Ni(II) at DME are reported below.
10
5
Effect of pH: The polarogram of 4 ppm Ni(II), 3.6 mM
Amm 4-PP-DTC and 3.8 mMAmm 4-BP-DTC in ammonium
chloride medium (0.3/0.4 M forAmm 4-PP-DTC/Amm 4-BP-
DTC) are recorded in the pH range 0.5-10.0. Precipitations of
Ni(II)-dithiocarbamate were not formed at any pH. The peak
current increased upto pH 6.8 in case of bothAmm 4-PP-DTC/
Amm 4-BP-DTC and the peak potentials shifted towards more
negative values with the increase in pH. Further, increase in
pH, the peak current decreases. Hence, the pH = 7 where the
peak has maximum height was fixed as the optimum value for
all other studies. The results are shown in Fig. 2.
0
0
0.2
0.4
Ammonium chloride (M)
0.6
0.8
Fig. 3. Effect of supporting electrolyte for the determination of Ni(II) with
Amm 4-PP-DTC and Amm 4-BP-DTC
Effect of reagent concentration:The influence of dithio-
carbamate on the polarographic characteristics of Ni(II)-dithio-
carbamate complexes were studied using 4 ppm Ni(II) ion in
0.3/0.4 M ammonium chloride for Amm 4-PP-DTC/Amm 4-
BP-DTC respectively at pH 6.8. The dithiocarbamates concen-
trations were varied in the range of 0.2-5.0 mM. The peak
current increases with dithiocarbamate concentration and tends
to a limiting value similar in the form to the Langmuir adsorp-
tion isotherm (Figs. 4 and 5). The reagent concentration at
maximum wave height was fixed as 3.6 and 3.8 mM forAmm
4-PP-DTC andAmm 4-BP-DTC respectively. The peak potential
shifted to more negative potential with increase in dithiocarba-
mates concentration and beyond the optimum concentration,
the peak potential, as well as height remained constant.
Effect of mercury pressure: Effect of height of the mercury
column on Ni(II)-dithiocarbamate complexes were studied
maintaining the optimum conditions as already fixed. The
catalytic current decreases with the increase in the height of
35
30
25
20
15
10
5
0
Amm 4-PP-DTC
Amm 4-BP-DTC
the mercury column and i / h values decreases, whereas
nickel reduction wave increases with the pressure following
diffusion controlled nature and i / h is constant (Table-1).
C
5
7
9
11
C
pH
Fig. 2. Effect of pH for the determination of Ni(II) with Amm 4-PP-DTC
and Amm 4-BP-DTC
30
2
2
1
1
5
0
5
0
5
0
Effect of supporting electrolyte concentration:The effect
of supporting electrolyte concentration on the peak current is
investigated by employing the solution containing 4.0 ppm
Ni(II) and 3.6/3.8 Amm 4-PP-DTC/Amm 4-BP-DTC respec-
tively. The concentration of ammonium chloride was changed
in the range of 0.05 - 6.0 M and the polarograms were recorded
maintaining pH of the solution at 6.8 (Fig. 3). The peak height
was increased with ammonium chloride concen-tration upto
Amm 4-PP-DTC
Amm 4-BP-DTC
0
.3 and 0.4 M in case of Amm 4-PP-DTC/Amm 4-BP-DTC
respectively. With further increase in concentration, the peak
height also decreases. The concentration of ammonium chloride
was therefore fixed at the maximum peak height value. The
peak potential shifted slightly towards positive potential with
ammonium chloride concentration.
0
1
2
3
4
5
Dithiocarbamate (mM)
Fig. 4. Effect of reagent concentration for the determination of Ni(II) with
Amm 4-PP-DTC and Amm 4-BP-DTC

Vol. 27, No. 10 (2015)
Novel Dithiocarbamates for Electrochemical Detection of Nickel(II) in Environmental Samples 3601
0
0
0
0
0
.25
.20
.15
.10
.05
0
Effect of temperature: The current-voltage curves for
the system containing 4 ppm Ni(II), 3.6 mMAmm 4-PP-DTC,
0
4
.3 M NH Cl at pH 6.8 and 3.8 mM Amm 4-BP-DTC, 0.4 M
NH Cl at pH 6.8 in the presence of 0.002 % Triton X-100 were
4
recorded at various temperatures from 20-50 °C. It was found
that with increase in temperature the catalytic wave height
increases and the temperature coefficient values have gradually
drops down upto 35 °C. Above 35 °C the current, i
completely temperature independent.
C
become
Effect of nickel(II) on peak current: The effect of Ni(II)
in the range of 0.05-6.0 ppm was studied on the peak current
in the presence of optimum concentrations of dithiocarbamate
and ammonium chloride at fixed pHs and Triton X-100. The
current-voltage curves shows that the peak height increases
linearly with the Ni(II) concentration and the obtained results
were illustrated in Fig. 6.
Amm 4-PP-DTC
Amm 4-BP-DTC
0
1
2
3
4
5
6
Dithiocarbamate (mM)
Fig. 5. Langmuir adsorption isotherm plot for the determination of Ni(II)
with Amm 4-PP-DTC and Amm 4-BP-DTC
4
0
5
Amm 4-PP-DTC
Amm 4-BP-DTC
3
TABLE-1
EFFECT OF MERCURY PRESSURE FOR THE DETERMINATION
OF Ni(II) WITH Amm 4-PP-DTC AND Amm 4-PP-DTC
30
Height of
the mercury
column (cm)
Amm 4-PP-DTC
Current
Amm 4-BP-DTC
25
20
15
10
5
0
Current
iC / h
iC / h
(µA)
25.60
24.75
24.60
23.40
(µA)
24.40
21.60
19.70
18.55
22
27
32
37
5.598
4.979
4.271
3.726
4.367
3.598
3.034
2.893
Effect of maximum suppressor: For a solution containing
ppm Ni(II), dithiocarbamate 3.6/3.8Amm 4-PP-DTC/Amm
-BP-DTC at pH 6.8 with gelatine in the range 0.005-0.001 %
4
4
0
2
4
6
8
and 0.002-0.004 % Triton X-100 were added and the effect
was studied.
It was found that Ni(II) reduction wave was suppressed
slightly by adding gelatine and the catalytic wave reduced to
about 10 % upto 0.005 % of gelatine. The peak potential shifted
towards less negative potentials.
Triton X-100 has no effect on Ni(II) reduction as well as
on the catalytic peak current and peak potential. However, the
presence of Trition X-100 improves the catalytic wave to a
well defined and a symmetrically one with a clear base line.
Nickel(II) (ppm)
Fig. 6. Effect of nickel(II) on peak current for the determination of Ni(II)
with Amm 4-PP-DTC and Amm 4-BP-DTC
The Ni(II) reduction wave also increases with increase in
Ni(II) concentration without any shift in peak potential. The
catalytic wave also increases linearly with Ni(II) concentration.
Effect of foreign ions: Various metal ions commonly
associated with Ni(II) like Fe(II), Cu(II), Cr(VI), Zn(II), Mo(VI)
andAl(III) have been used in the present study to evaluate the
change that occur in the catalytic wave of Ni(II)-dithiocarba-
mate system. The concentration of Ni(II) was maintained at
0
.002 % of Triton X-100 was therefore, maintained for all
studies and the results were tabulated in Table-2.
4
ppm and 100-fold excess of foreign ions were added. Of all
the metal ions studied Fe(II) and Cu(II) form precipitates with
dithiocarbamates in the conditions where Ni(II)-dithiocarba-
mate complex gives a catalytic wave. Aluminium(III) does
not interfere whereas Cr(VI) gives catalytic current with peak
potentials at -1.56 V and -1.65 V vs. SCE and suggests that a
simultaneous determination of Ni(II) and Cr (VI) is possible
without any separation or adding masking agents. Zn(II) inter-
feres in the determination of Ni(II), but it was masked by adding
TABLE-2
EFFECT OF MAXIMUM SUPPRESSORS FOR
THE DETERMINATION OF Ni(II) WITH
Amm 4-PP-DTC AND Amm 4-BP-DTC
Maximum
suppressor (%)
Current (µA)
Amm 4-PP-DTC
Amm 4-BP-DTC
Gelatin
24.00
22.70
18.70
Triton X-100
24.00
0.000
0.002
0.004
23.00
20.60
18.30
5
mL of 2 % sodium tartrate solution. Mo (VI) severely
interferes by increasing the wave height of Ni(II) and the peak
potential shifts towards more negative values. Se(IV), Th(IV),
Ce(IV) and Sn(II) also do not interfere upto 100-fold excess
with the Ni(II)-dithiocarbamtes system.
0.00
23.00
23.00
23.00
0
0
.005
.010
24.00
24.00

3
602 Niranjan et al.
Asian J. Chem.
Anions such as fluoride, bromide, iodide, tartrate, sulphate,
Application of the catalytic hydrogen current method to
real samples: The method was extended to the analysis of trace
quantities of Ni(II) in various waters and agricultural materials.
Drinking water samples:1 L of the water samples collected
from industrial estate and aroundAmararaja batteries (Tirupati
town, India) were preconcentrated to 100 mL.
Agricultural materials: 5 g of Hibiscus cannabinus
(Gongura), Rumex vesicarius (Chukkaku) and 10 g of Phaeolus
vulgaris (Beans), Pisum sativum (Peas) samples are digested by
dry ash method and made upto 25 mL with triple distilled water.
The amount of Ni(II) present in the samples was determined
by referring its current to the calibration curve drawn with
standard solutions of Ni(II). The amount of Ni(II) obtained
by catalytic polarographic method was further supported by
AAS method. The results in Tables 3 and 4 reveals that the
thiosulphate, phosphate, carbonate, oxalate, nitrite and nitrate
do not interfere with the catalytic current of Ni(II)-dithiocar-
bamate. Perchlorate and thiocyanate interfere with the wave
by reducing the wave height nearly 40 % and EDTA interferes
severely by completely suppressing the Ni(II) catalytic wave.
Effect of indifferent cations: The effect of neutral salts
on Ni(II)-dithiocarbamate catalytic waves has been studied
by adding several concentrations of different chlorides of
sodium, potassium, lithium and calcium keeping the value of
the quantitative experimental conditions in the solution constant.
The increase in ionic strength due to the addition of neutral
salts results in a continuous decrease in catalytic current and
also in wave height in the presence of sodium chloride was
little less to that of potassium chloride and the decrease was
more for lithium chloride and much more for calcium chloride
(
Fig. 7a and 7b). The peak potential shifts towards less negative
TABLE-3
DETERMINATION OF Ni(II) WITH Amm 4-PP-DTC IN WATER
SAMPLES COLLECTED AROUND TIRUPATI, INDIA USING
CATALYTIC HYDROGEN CURRENT (CHC) TECHNIQUE
potential in all cases.
3
3
2
2
1
1
5
0
5
0
5
0
5
0
CHC Method
AAS Method
(DC polarography)
KCl
Ni(II)
added
Amm 4-PP-DTC
Amm 4-PP-DTC
NaCl
LiCl
Ni(II)
found
(ppm)
Recovery
(%) ±b
Ni(II)
found
(ppm)
Recovery
(%) ±
R.S.D.
(ppm)
b
CaCl2
R.S.D.
1
.0
.2
1.07
1.18
1.61
1.80
2.13
1.05
1.24
1.69
1.82
2.07
98.93±2.43
98.82±2.75
98.39±2.47
98.20±2.82
99.87±2.59
98.95±2.32
98.76±2.72
99.31±2.60
98.18±2.96
97.93±2.54
1.05
1.28
1.64
1.91
2.10
1.02
1.29
1.75
1.95
2.05
98.95±2.15
98.72±2.15
98.36±2.74
99.09±2.80
97.90±2.89
98.98±2.35
98.71±2.72
98.25±2.74
98.05±2.58
97.95±2.48
1
I
1.6
1.8
2.0
1.0
1.2
II
1.6
1
.8
.0
0
0.1
0.2
Concentration (M)
Fig. 7a. Effect of indifferent ions on Ni(II)-Amm 4-PP-DTC complex at
0.3
0.4
0.5
0.6
2
a
I: Industrial estate; II: Amararaja Batteries, 5 mL of the concentrated
b
sample is used; Relative standard deviation (n = 6)
(
DME) for the determination of Ni(II)
TABLE-4
3
3
2
2
1
1
5
0
5
0
5
0
5
0
DETERMINATION OF Ni(II) WITH Amm 4-BP-DTC IN WATER
SAMPLES COLLECTED AROUND TIRUPATI, INDIA USING
CATALYTIC HYDROGEN CURRENT (CHC) TECHNIQUE
KCl
NaCl
LiCl
CHC Method
AAS Method
(
DC polarography)
Ni(II)
added
Amm 4-BP-DTC
Amm 4-BP-DTC
CaCl2
Ni(II)
found
Recovery
(%) ±b
Ni(II)
found
(ppm)
Recovery
(%) ±
R.S.D.
(ppm)
b
(
ppm)
1.08
1.24
1.63
1.91
2.13
1.06
1.18
1.72
1.87
2.08
R.S.D.
1
.0
.2
98.92±2.52
98.76±2.58
98.37±2.35
98.09±2.86
97.87±2.69
98.94±2.36
98.82±2.34
98.28±2.61
98.13±2.89
97.92±2.35
1.04
1.24
1.64
1.92
2.14
1.02
1.29
1.74
1.95
2.05
98.96±2.15
98.76±2.35
99.36±2.84
98.08±2.85
97.86±2.89
98.98±2.35
98.71±2.72
98.26±2.64
98.05±2.50
97.95±2.35
1
I
1.6
1.8
2.0
1.0
1.2
II
1.6
1.8
2.0
0
0.2
0.4
0.6
Concentration (M)
a
Fig. 7b. Effect of indifferent ions on Ni(II)-Amm 4-BP-DTC complex at
DME) for the determination of Ni(II)
I: Industrial estate; II: Amararaja Batteries, 5 mL of the concentrated
of sample is used; Relative standard deviation (n = 6)
b
(

Vol. 27, No. 10 (2015)
Novel Dithiocarbamates for Electrochemical Detection of Nickel(II) in Environmental Samples 3603
TABLE-5
DETERMINATION OF Ni(II) WITH Amm 4-PP-DTC IN AGRICULTURAL SAMPLES
AROUND TIRUPATI, INDIA USING CATALYTIC HYDROGEN CURRENT TECHNIQUE
CHC Method (DC polarography)
Amm 4-PP-DTC
AAS Method
a
Ni(II)
added
Sample
Amm 4-PP-DTC
Scientific/Local name
Ni(II) found
Recovery (%)
± R.S.D.
Ni(II) found
(ppm)
Recovery (%)
b
(ppm)
b
(
ppm)
± R.S.D.
Vegetables
Pisum sativum/Peas
Phaseolus vulgaris/Bean
1.0
1.0
1.12
1.10
98.88 ± 2.570
98.90 ± 2.152
1.13
1.10
98.87 ± 2.12
98.90 ± 2.23
Leafy vegetables
98.98 ± 2.40
98.92 ± 2.99
Rumex vesicarius/Chukkaku
1.0
1.0
b
1.02
1.08
1.05
1.04
98.95 ± 2.08
98.96 ± 2.45
Hibiscus cannabinus/Gongura
a
5
mL of concentrated sample is used; Relative standard deviation (n = 6)
TABLE-6
DETERMINATION OF Ni(II) WITH Amm 4-BP-DTC IN AGRICULTURAL SAMPLES
AROUND TIRUPATI, INDIA USING CATALYTIC HYDROGEN CURRENT TECHNIQUE
CHC Method (DC polarography)
Amm 4-PP-DTC
AAS Method
Amm 4-BP-DTC
a
Ni(II)
added
Sample
Scientific/Local name
Ni(II) found
Recovery (%)
± R.S.D.
Ni(II) found
(ppm)
Recovery (%)
± R.S.D.
(ppm)
b
b
(
ppm)
Vegetables
Pisum sativum/Peas
Phaseolus vulgaris/Bean
1.0
1.0
1.18
1.08
98.82 ± 2.57
98.92 ± 2.17
1.15
1.10
98.85 ± 2.81
98.90 ± 2.12
Leafy vegetables
98.96 ± 2.18
98.99 ± 2.57
Rumex vesicarius/Chukkaku
1.0
1.0
b
1.04
1.01
1.05
1.04
98.95 ± 2.18
98.96 ± 2.15
Hibiscus cannabinus/Gongura
a
5
mL of concentrated sample is used; Relative standard deviation (n = 6)
various water samples analyzed contain traces of Ni(II) are
within the tolerance limits and the percentage recovery values
obtained with the two ligands are comparable and in good
agreement with AAS method. The Ni(II) content present in
agricultural materials, Hibiscus cannabinus (Gongura), Rumex
vesicarius (Chukkaku), Phaeolus vulgaris (Bean) and Pisum
sativum (Peas) showed that the values were in agreement with
the standard values (Tables 5 and 6).
These observations indicate that the catalytic hydrogen
current method proposed for Ni(II) usingAmm 4-PP-DTC and
Amm 4-BP-DTC in ammonium chloride-ammonium hydroxide
medium may be successfully applied for the determination of
low concentration of Ni(II) present in waters and agricultural
materials.
ACKNOWLEDGEMENTS
The authors are grateful to University Grants Commission
UGC), New Delhi, India for providing financial support
through UGC-BSR-RFSMS (Research Fellowship in Sciences
for Meritorious Students) Fellowship (F.4-1/2006(BSR)/7-187/
(
2
007(BSR), dated 18-07-2012.
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