Anal. Method Environ. Chem. J. 3 (3) (2020) 65-75
Research Article, Issue 3
Analytical Methods in Environmental Chemistry Journal
Journal home page: www.amecj.com/ir
AMECJ
Speciation of chromium in blood samples based on
dithioglycerol immobilized on carbon nanotube by dispersive
micro solid phase bioextraction
Naseh Esmaeili
a
, Eskandar Kolvari
a
and Jamshid Rakhtshah
b,*
a,*
Department of chemistry, Faculty of Science, Semnan University, Semnan, Iran
b,*
Department of Inorganic Chemistry, Faculty of Chemistry, University of Tabriz, Tabriz, Iran
ABSTRACT
A novel method based on the synthesis of dithioglycerol immobilized
on carbon nanotubes (CNTs@DTG) was used for speciation of
chromium (Cr
III
and Cr
VI
) in human blood samples by dispersive
mixture containing acetone and 1-octyl-3-methylimidazolium
6
-1
of Cr
III
and Cr
VI
which was diluted with DW up to 10 mL at optimized
by HS of
and Cr(VI) ions were back-extracted from the IL/ CNTs@DTG to the
aqueous phase by changing pH for each of them before determined
chromium was calculated by summarizing Cr
III
and Cr
VI
content.
-1
and 30 ng L
-1
Keywords:
Dithioglycerol immobilized on carbon
Dispersive micro solid phase
bioextraction
ARTICLE INFO:
Received 5 Jun 2020
Revised form 3 Aug 2020
Accepted 27 Aug 2020
Available online 30 Sep 2020
Corresponding Author: Jamshid Rakhtshah
https://doi.org/10.24200/amecj.v3.i03.114
------------------------
1. Introduction
Heavy metals accumulate in different human tissues
enter to the human body from foods and waters
and absorb them by the gastrointestinal system.
human biological matrix have a toxicological effect
chromium pollutants in the environment is chemical
. The chromium has two species (Cr
III
and Cr
VI
) in the environment with different toxicity and
physiological effects in humans. The metabolism of
on Cr (III) compounds in humans
(VI) is toxic and causes cancer in humans. Due to the
cells and damage the proteins and DNA of the
.
the concentration chromium in water less than 2
66
Anal. Method Environ. Chem. J. 3 (3) (2020) 65-75
µg L
-1
as normal range and toxicity
in waters
announced that the value of 0.1-1.7 µg L
-1
and
0.24-1.8 µg L
-1
for normal chromium in blood and
urine samples
techniques such as inductively coupled plasma
mass spectrometry
spectrometry and electrothermal atomic
were used for
in human samples caused to use of these techniques
analytical chemistry based on ionic liquids (ILs) as
of the sample preparation with green solvent.
dispersive micro solid phase extraction and the
applied
as sample preparation. The ILs as an organic salt
thermal stability about 200-350
°
good extractability and separation phase . The
different adsorbents such as multi-walled carbon
magnetite nanoparticles
of magnetic particles imprinted cellulose based
biocomposites were used for extraction and
separation of chromium ions in a different matrix.
develop a new procedure based on CNTs@DTG
adsorbent for the speciation of trace amount of Cr (III)
and the performance of the proposed method was
6
separation nanoparticles of CNTs@DTG from blood
samples.
2. Experimental
2.1. Apparatus
Chromium determination was done based on a spectra
electrothermal atomic absorption spectrometer
accessory. All operating parameters were set based on
357.9 nm with 0.2 nm slit was adjusted. All volumes
auto-sampler 3000. The instrumental and extraction
conditions are listed in Table 1. The temperature
programming for chromium was shown in Table
2. The pH of the solutions and human samples
with high sensitivity was used for determining of
1.0 L min
-1
-
1
). An ultrasonic bath for molecular biology such as
blood samples with temperature controlling in real-
Table 1.
ValuesParameters
357.9 nm
0.2 nm
6 mA
Automatic
Wavelength
Slit
Lamp current
Injection mode
Volume Injection
67
Speciation of chromium by CNTs@DTG nanostructure Jamshid Rakhtshah et al
2.2. Reagents and materials
All reagents with ultra-trace analytical grade
stock solution were prepared from an appropriate
amount of the nitrate salt of this analytes as 1000 mg
L
-1
solution in 0.02 mol L
-1
3
solutions were prepared daily by dilution of the stock
solution. The dithioglycerol material
Germany. The buffer solution was 0.3 mol L
-1
CH
3
0.2 molL
-1
of sodium phosphate buffer solution from
the pH of 5.5 to 8.2 (Na
2
4
/NaH
2
4
3
6
from Sigma Aldrich (Germany).
2.3. Sample preparation of human blood
a 1.0 mol L
-1
3
solution for one day and
thoroughly rinsed for 6 times with DW. As
(not chromium) was added to a 5 mL blood sample.
The human blood sample was maintained at -20
samples was considered for sampling and analysis
with permit form for all patients.
2.4. Synthesis of CNTs@DTG
to the acid oxidation method and the CNTs@
mL of dry xylene were sonicated for 15 minutes in
2
atmosphere to remove the produced HCl. The
product of CNTs@Cl was cooled down to room
mL of DTG were mixed in 60 mL ethanol using an
(Fig. 1).
Table 2.
Ar ow rate (mL min
−1
)Hold time (s)Ramp time (s)Temperature (
◦
C)Step
3001515120Dry
30015301150Ash
0.0212500Atomize
300212600Clean
Pristine
CNTs
CNTs@OH
HO
HO
HO
HO
CNTs@DTG
CNTs@Cl
O
O
Si
MeO
O
O
O
Si
MeO
Cl
S
S
Cr
OH
SH
HS
1.
HNO
3
,
H
2
SO
4
2.
NaBH
4
Methanol
CPTMS
Dry
Xylene
NEt
3
Fig. 1. Representation of the formation of CNTs@DTG.
68
Anal. Method Environ. Chem. J. 3 (3) (2020) 65-75
2.5. The extraction procedure
samples were used for speciation and determination
6
acetone added to standard and human blood samples
with Cr (III) and Cr (VI) concentration between
0.05-1.8 µg L
were extracted with the HS group of CNTs@DTG
CrIII
+
+
:(SH
2
-
SH
2
6
in the bottom of the conical tube by centrifuging
samples for 5 min. The upper phase was removed
3
to 0.2 mL. The total chromium (T-Cr) was simply
calculated by summarizing Cr (III) and Cr (VI)
content (Table 3). The procedure used for a 10 blank
curves before and after preconcentration process
(tga=m
1
/m
2
Table 3.
ValuesFathers
6.0
2.0
5 mL
-1
R = 0.9996
0.5 mL
1 and 0.5 mol L
-1
3 min
5min
Working pH of Cr(III)
Working pH of Cr (VI)
Volume of back-extraction (eluent)
3
Amount of IL
Volume of dispersant solvent (Acetone)
Shaking time
Centrifugation time
Fig.2. Fig.3.
69
Speciation of chromium by CNTs@DTG nanostructure Jamshid Rakhtshah et al
3. Results and discussion
3.1. Characterizations
The hydroxyl-functionalized CNTs are used for the
respectively.
absorption band corresponding to the C=C bond
at 1570 cm
-1
cm
-1
the CNTs. saw the absorption band of the
-1
the absorption bands at the range of 2500-3000
cm
-1
successful functionalization of CNTs with Cl-
alkylsilane material. The appearance of a band at
2625 cm
-1
the CNTs@DTG adsorbent.
3.2. Effect of ETAAS conditions
of 30 s for water evaporation with 40s of ramp
Abs was studied within a range of 600-1400
C.
The maximum Abs was obtained from 1000 to
1200
C
was selected as the optimum
determination was examined between 2000–3000
and the maximum signal was obtained at 2.500
C.
Cleaning time and temperature were ordered at 3 s
and 2.600
mL min
.
3.3. Effect of pH on the extraction
Cr (VI) ions on CNTs@DTG was investigated
of chromium concentration. The chemical and
physical adsorption was strongly conditioned by the
pH of solutions. The results show that the highest
applied to the speciation of two forms of chromium
at pH 2 and 6 as optimum points for Cr (VI) and
procedure (Fig. 5).
Fig.4.
70
Anal. Method Environ. Chem. J. 3 (3) (2020) 65-75
3.4. Effect of sample volume and amount of
ionic liquid
Sample volume is one of the most important
parameters to be studied. The effect of sample
volume between 2-20 mL was studied for 1.0
of Cr (III) and Cr (VI) ions. Quantitative
extraction was observed between 2 ml and 10 ml.
The recovery was decreased by more than 10 mL of
the ionic liquid is partially solubilized in the
liquid phase and leads to non-reproducible results.
(Fig.
6)
the procedure was remarkably dependent on the
6
the quantitative extraction was obtained more than
6
of 0.1 g was selected as optimum mass for ionic
liquid for collecting and separating CNTs@DTG
from the liquid phase (Fig. 7).
3.5. Effect of CNTs@DTG mass
Fig. 5. The effect of pH on extraction and speciation of Cr (III)
Fig. 6. The effect of sample volume on extraction and speciation of
71
Speciation of chromium by CNTs@DTG nanostructure Jamshid Rakhtshah et al
CNTs@DTG adsorbent between 5-35 mg were
examined for Cr (III) and Cr (VI) extraction by
quantitative recoveries in human blood samples were
obtained with 20 mg and 25 of CNTs@DTG for Cr
(Fig. 8).
3.6. Effect of eluent on recovery
The Cr (III) and Cr (VI) were back-extracted from
dissociate and release into the liquid phase. Different
3
H
2
4
were selected for investigating of chromium
back-extraction from the CNTs@DTG /IL phase.
The research showed that 1 mol L
3
and
0.5 mol L
(III) and Cr (VI) from the CNTs@DTG /IL phase.
3.7. Effect of interference ions on extraction
by the extraction chromium in blood samples.
Fig. 7. The effect of ionic liquids mass on extraction and speciation of
Fig. 8. The effect of CNTs@DTG mass on extraction and speciation of
72
Anal. Method Environ. Chem. J. 3 (3) (2020) 65-75
metal ions in blood were selected for evaluating
of potential interfering ions on the extraction of
-1
of Cr (III) and Cr (VI) and 1-2 mg L
-1
of different ions in the matrix were used. The
tolerate amounts of each ion had less than 5% of
the absorbance alteration. The results showed
interference ions do not decrease the extraction of
chromium in optimized conditions. The results are
shown in Table 4.
3.8. Validation of D-μ-SPBE procedure
(VI)
and Cr (III)
in 10 mL of human blood samples
(Table
5)
for determination of Cr (III) and Cr (VI) in human
(Table
6)
of the system in the determination of Cr (VI)
and Cr
(III) in human blood samples. The calibration curve
after the preconcentration process. The
Cr (VI) enters to the cytoplasm of red blood cells
total concentration of Cr in blood was calculated
by summarizing of Cr (VI) and Cr (III) which was
a low concentration in serum or plasma samples as
compared to blood samples.
Table 4. The effect of matrix ions on the determination of Cr (III)
Ions Maximum tolerance ratio
(matrix ion conc./Cr conc.)
Recovery (%)
Cr (VI)
Cr (III) Cr (VI)
Cr (III)
K
+
+
+
2+
2+
1100 900 97.4 98.3
2+
+2
2+
850 700 98.2 96.5
Cd
2+
2+
500 600 99.2 97.7
Cl
-
-
-
3
-
-
1200 1000 98.1 96.8
4
3-
3
2-
4
2-
900 750 97.5 98.2
Ag
+
2+
2+
200 250 95.3 97.6
3+
V
3+
500 650 96.8 98.9
Table 5.
a
Sample Added
(μg L
-1
) *ICP-MS (μg L
-1
) *Found (μg L
-1
)
a
Recovery (%)
A ------ 1.22 ± 0.02 1.19 ± 0.06 97.5
1.0 ------ 2.15 ± 0.07 96.0
------ 1.51 ± 0.03 1.54 ± 0.08 101.9
1.5 ------ 2.97 ± 0.14 95.3
C ------ 2.04 ± 0.05 1.98 ± 0.11 97.1
1.5 ------ 3.43 ± 0.16 96.6
D ------ 0.55 ± 0.01 0.58 ± 0.02 105.4
0.5 ------ 1.06 ± 0.05 96.0
*
a
73
Speciation of chromium by CNTs@DTG nanostructure Jamshid Rakhtshah et al
4. Conclusion
speciation and determination of trace amount of
the amount of IL and pH were studied and
ionic liquid helps to provide a reliable and
efficient extraction for speciation of Cr (III) and
Cr (VI) in blood samples as an environmentally
friendly solvent for collecting of CNTs@DTG
adsorbent from the liquid phase. The enrichment
32 ng L
-1
and 28 ng L
-1
for Cr (III) and Cr (VI)
procedure were used for speciation of Cr (III)
and Cr (VI) in human blood samples in a short
time as compared to other methods. The mean of
-1
for 5.0 mL of
of the methodology was confirmed by spiking
proposed procedure was successfully used to
speciation and separation of Cr (III) and Cr (VI)
in human blood samples.
5. Acknowledgements
for supporting this work. The authors wish to
thank the workers for their kindness and voluntary
participation in this study. This study was supported
the goals and stages of the study were explained
to the participants and they were asked to sign the
informed consent form.
6. References
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Table 6. Validation of chromium speciation based on CNTs@DTG in human serum
Sample Added
(μg L
-1
) Found (μg L
-1
)
a
Total
a
Recovery (%)
Cr (III) Cr (VI) Cr (III) Cr (VI) Cr (III) Cr (V)
Blood
--- --- 1.45 ± 0.08 0.26 ± 0.02 1.71 ± 0.09 --- ---
1.5 --- 2.93 ± 0.15 0.24 ± 0.01 3.17 ± 0.29 98.6 ---
--- 0.2 1.47 ± 0.09 0.45 ± 0.02 1.92 ± 0.11 --- 95.0
Blood
--- --- 1.61 ± 0.11 0.76 ± 0.03 2.37 ± 0.12 --- ---
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1.5 --- 3.38 ± 9 0.16 ± 0.01 3.56 ± 0.16 97.3 ---
--- 0.2 1.89 ± 0.33 ± 0.01 2.22 ± 0.11 --- 95
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75
Speciation of chromium by CNTs@DTG nanostructure Jamshid Rakhtshah et al
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