Anal. Methods Environ. Chem. J. 4 (2) (2021) 72-85
Research Article, Issue 2
Analytical Methods in Environmental Chemistry Journal
Journal home page: www.amecj.com/ir
AMECJ
Ionic liquid functionlized on multiwall carbon nanotubes for
nickel and lead determination in human serum and urine
samples by micro solid-phase extraction
Arezou Laria, Naseh Esmaeilib,* and Homanaz Ghafaric
aSystems Biomedicine Department, Pasteur Institute of Iran, Tehran, Iran.
b Department of chemistry, Faculty of Science, Semnan University, Semnan, Iran
CDepartment of pharmacology,school of medicine,Tehran university of medical sciences, P.O.Box784-13145,Tehran,Iran
ABSTRACT
In this study, a novel synthesis adsorbent, 1-(3-aminopropyl)-3-
methylimidazolium hexauorophosphate functionlized on multiwall
carbon nanotubes ([Apmim][PF6]-MWCNTs, IL@MWCNTS)
was used for nickel/lead (Ni/Pb) extraction and determination by
dispersive ionic liquid micro solid-phase extraction (DIL-μ-SPE)
coupled to electrothermal atomic absorption spectrometry (ET-AAS).
After dilution of 20 mg of IL@MWCNTS in 200 μL of acetone, the
mixture was injected to 10 mL of human serum/urine samples at pH
of 8.0. After sonication for 5 min, the Ni(II) / Pb(II) were extracted by
ionic liquid phase and then centrifuged for 2.5 min. The upper liquid
phase set aside and Ni(II) / Pb(II) loaded in adsorbent were back-
extracted by acidic solution at pH=2-3. Finally, the concentration of
total nickel and lead was determined by ET-AAS. By optimizing, the
limit of detection, linear range, and enrichment factor for nickel and
lead were obtained (0.05 μg L−1; 0.1 μg L−1), (0.2-5.8 μg L−1; 0.4-
30 μg L−1) and 24.7; 5.1, respectively (RSD less than 5%). Also, the
capacity absorption of IL@MWCNTS for nickel and lead ions were
achieved 149.3 mg g-1 and 162.5 mg g-1, respectively. The DIL-μ-SPE
procedure was validated for nickel and lead extraction by spiking of
real samples and ICP-MS analyzer.
Keywords:
Nickel and lead,
Human samples,
Ionic liquid,
Multiwall carbon nanotubes,
Micro solid-phase extraction
ARTICLE INFO:
Received 11 Mar 2021
Revised form 15 May 2021
Accepted 4 Jun 2021
Available online 30 Jun 2021
*Corresponding Author: Naseh Esmaeili
Email: esmaeilin@gmail.com, esmaeilin@semnana.ac.ir
https://doi.org/10.24200/amecj.v4.i02.144
------------------------
1. Introduction
Lead and nickel (Pb, Ni) have toxic effects and
use in different industries. Heavy metals as non-
essential elements have widely distributed in the
environment (air, soils, waters) and humans. Human
exposure of heavy metals cause to various diseases
such as cancer. Pb and Ni is a naturally occurring
element found in small amounts in the earth’s crust
[1]. While it has some benecial uses, it can be toxic
to humans and animals, and cause to health effects.
The most exposure of lead and nickel related to
human activities including, the fossil fuels, gasoline,
the industrial facilities, the nickel cadmium battery,
and paint factories. Lead and nickel compounds
have been used in a wide variety of products found in
different industries, including paint, ceramics, pipes
and plumbing materials, gasoline, batteries, and
cosmetics [2, 3]. High levels of human exposure to
Ni and Pb metals cause to damage the most of human
organ systems such as, the central nervous system
(CNS), kidneys, liver, bones and gastrointestinal
system. Lead can also effect on hemoglobin
synthesis and cause to anemia effects or accumulate
in the bones. Depending on the level of exposure,
73
the lead and nickel can adversely effect on the
nervous system, immune system, reproductive and
the cardiovascular system [4-7]. Infants and young
children are especially sensitive to lead exposures,
which may contribute to behavioral problems,
learning decits and lowered IQ [8]. Lead can also
be emitted into the environment from industrial
sources and contaminated sites, such as former lead
smelters. While natural levels of lead in soil range
between 50 and 400 parts per million, mining,
smelting and rening activities have resulted
in substantial increases the lead levels in the
environment, especially near mining and smelting
sites. Lead can be added to soils and sediments
through deposition from sources of lead by air
pollution. Lead can be added to proteins and amino
acids which was caused neurological problems
[9,10]. Due to the environmental protection agency
(EPA), the maximum contaminant level (MCL) for
Pb in waters is zero and has no effect in humans
[2]. Also, the National toxicology program (NTP)
announced that the lead concentration in blood
and serum must be less than 50 µg L-1 in children.
The variable lead values in human blood/serum
was about 250 -300 µg L-1 which was reported
by food and drug administration (FDA) [11]. As
references, the standard blood lead levels are
below 25 mg dL-1 or 250 microgram per liter. The
permissible exposure level in the ambient (air,
water, soil, etc.) environment has been reported
[12-14]. Nickel (Ni) caused to acute disease in
humans [15]. Ni(II) can be enter to waters from
waste water of different industries such as battery
and electroplating factories [16]. Nickel complex
to various proteins and enzyme in the human
body. Nickel toxicity caused to many problems in
human systems or organs such as renal, liver, brain,
cardiovascular system, immune system and heart.
The symptoms diseases included lung dysfunction
and cancer was seen for nickel exposure [17].
Oral values for rats range from 67-9000 mg Ni
per kg (ATSDR). Toxic effects of oral exposure
to nickel usually involve the kidneys (ATSDR).
Normal range for Ni in healthy peoples is 0.2 µgL-1
in serum and less than 3.0 µgL-1 in human urine.
[18,19]. Nickel (II) in urine and serum samples
determined with UV-VIS spectrophotometry and
ame atomic absorption spectrometry techniques
[20]. Recently, the various techniques such as, the
inductively coupled plasma(ICP), the inductively
coupled plasma mass spectrometry(ICP-MS) [21],
the ame atomic absorption spectrometry F-AAS
[22], the X-ray uorescence spectrometry [23] and
the electrothermal atomic absorption spectrometry
(ET-AAS) were used to determine Ni and Pb
ions in different matrixes [24]. Due to ultra-trace
concentration of Pb and Ni in human samples
(urine and serum) and difculty matrices in human
biological samples, the sample treatment was used.
For Examples, the solid phase extraction(SPE)
[25], the magnetic dispersive micro-solid phase
extraction (MD-μ-SPE) [26,27], the dispersive
micro solid phase microextraction (D-SPME)
[28], the needle hub in-syringe solid phase
extraction (NHS-SPE) [29], and liquid-liquid
microextraction (LLME) [30, 31] were used.
Among them, the dispersive micro solid-
phase extraction D-μ-SPE was mostly used
for determination of heavy metals such as Ni
and Pb in water and humans. Task ionic liquids
were used for extraction of heavy metals from
liquid phase by N, S groups. The D-μ-SPE
procedure have advantages such as easy to use,
simple, high recovery and efficient extraction.
In this process, the adsorbent properties are
main factor for heavy metal extraction by
D-μ-SPE procedure. The high surface area of
nanoparticles caused to increase the extraction
recovery and absorption capacity. Recently, the
various nanostructures were used for extraction
Pb and Ni in waters, human urine and serum
samples [32, 33]. In this study a novel ionic
liquid ([Apmim][PF6]) functionalized on
MWCNTs (IL-MWCNTs) was used for
extraction of Ni and Pb ions in human urine and
serum samples by the DIL-μ-SPE procedure.
The Ni and Pb concentration was determined
by the ET-AAS after sample preparation. The
main parameters on lead and nickel extraction
were studied and evaluated.
Nickel and Lead determination by[Apmim][PF6]-MWCNTs Arezou Lari et al
74
2. Materials and Methods
2.1. Apparatus
(Pal 3000) and deuterium (D2) /hollow-cathode lamp
(Ni, Pb) was used. The sample was transferred to 2 mL
of PVC tube in Pal3000 as auto-sampler accessory.
Table 1. The
lead determination was achieved by injecting 20 µL
of sample to graphite tube with auto-sampler in three
steps of drying, ashing, and atomization. The ICP-MS
analysis in different matrixes. The conditions of ICP-
MS were tuned for Ni and Pb determination in samples
(1200 W, 12 L min-1
was adjusted 1.2 L min-1. The quantitative analysis of
lead and nickel were obtained in PPT concentration by
ICP-MS analyzer (<10 ppt). The range of pH values
of the serum and urine samples were measured by
pH meter (Metrohm) and adjusted by favorite buffer
solution. The shaker accessory (USA, Domingo Lab)
by stirring speed between 10~210 PRM and working
platform of 315×218 mm (12.5”×8.5”) with voltage
220V was used.
place capacity in an aerosol-tight rotor and speeds up
to 21,300 × g was used (Laboratory centrifuge model
tube were purchased from Sigma (Germany). Fourier
transform infrared (FT‐IR) spectra were obtained by a
‐IR). X-ray diffraction
(XRD) was reported by a X’Pert PRO X-ray
diffractometer
images were achieved using a Tescan Mira-3.
2.2. Reagents
In this study, the analytical grade of reagents was
prepared from Merck / Sigma Aldrich (Germany). The
standard solution of lead (Pb2+) was purchased from
Merck CO. (Germany) with a concentration of 1000
mg L-1 in 1 % HNO3. The standard stock solutions
(1000 mg L-1) of Ni (II), were purchased from Merck
(Darmstadt, Germany). Another concentration of
lead and nickel was daily prepared by dilution of the
standard lead solution with DW. Ultrapure water was
for dilution of solutions or standards. The pH was
adjusted by sodium phosphate buffer solution for pH
5.7-8.2. The reagents such as acetonitrile (CAS N.:
75-05-08, Merck), polyoxyethylene octyl phenyl ether
(TX-100, CAS N: 9002-93-1, Sigma, Germany), and
toluene (CAS N: 108-88-3, Merck), HNO3, xylene,
HCl, ethanol, and acetone, were prepared from Merck,
Table 1.
Features Value Pb Value Ni
Linear range, µg L-1 3-90 5-85
Working range, µg L-1 3-150 5-145
Wavelength, nm 283.3,217.0 232.0
Lamp current, mA 5.0 4.0
Slit, nm 0.5 0.2
Mode Peak Area Peak Area
Auto Sampler (µL) 1-100 1-100
LOD 0.75 1.25
3.0 5.0
R20.9998 0.9997
Anal. Methods Environ. Chem. J. 4 (2) (2021) 72-85
75
Nickel and Lead determination by[Apmim][PF6]-MWCNTs Arezou Lari et al
Germany. MWCNTs adsorbent prepared from RIPI
company in Iran. aminoopropyltrimethoxysilane
(APTMS) was prepared from Sigma, Germany.
2.3. Synthesis of [Apmim][PF6]-MWCNTs
The carboxylic acid of MWCNTs was prepared by the
acid treatment procedure according to previous reports
[34]. Then, the carboxylic acid (COOH) on MWCNTs
was treated with NaBH4 / CH3OH, and COOH were
reduced to CH2OH groups. Typically, in a 100 mL
ask / condenser / magnetic stirrer (MSB), the sodium
borohydride (0.5 g) added to 5 g of MWCNTs-COOH
and in presence of methanol reuxed / cooled/ ltered
/ washed with methanol. Then 2.0 g of MWCNTs –
OH were added to 3-aminoopropyltrimethoxysilane
(APTMS) in xylene (50 ml) and heated. Then, the
product was ltered, washed with ethanol. Finally,
Immobilization of the carbonyl group on the MWCNTs
was accomplished by stirring the aminopropyl-
functionalized CNTs in an ethanolic solution of
terephthalaldehyde (0.5 g) for 3 h at 70 °C. An
ethanolic solution carbonyl-functionalized MWCNTs
were moved to ultrasonic bath for 15 minutes. After
the sonication, a solution of [Apmim][PF6]in EtOH
(10 mL) was added dropwise to mentioned suspension
during 10 min at 80 °C. The reaction mixture was
reuxed for 4 h at 80 °C by N2[34].
2.4. General procedure
By the DIL-μ-SPE procedure, 10 mL of human urine
and serum sample was used for extraction Pb and Ni
by IL-MWCNTs. Firstly, 10 mL of human samples
and standard solution containing 0.2 μg L−1; 0.4 μg L−1
(lower limit) and 5.5 μg L−1; 30 μg L−1 (upper limit) for
Ni and Pb was used, respectively at pH of 8.0. Then, 20
mg of IL-MWCNTs mixed with 0.2 mL of acetone and
injected to 10 mL samples /standard solution in PVC
centrifuge conical tube. The mixture was shaken for 6
min and Pb/Ni ions were extracted by amine group of
[Apmim][PF6] at optimized pH. Then, the adsorbent
was collected from liquid phase by centrifuging of
samples. Then, the Ni loaded on adsorbent was back
extracted with 0.2 mL of nitric acid (0.3 M) and diluted
with 0.2 mL of DW. Also, the lead loaded on adsorbent
was back extracted with 0.2 mL of nitric acid (0.3 M)
and diluted with DW up 2 mL. Finally, the solution
was determined by ET-AAS (Fig.1, Table 2). The
recovery of extraction with IL-MWCNTs adsorbent
was obtained for Pb/Ni concentration by the equation
1. The CA is the primary concentrations and CS is the
secondary concentration of Pb(II)/Ni(II), which was
determined by ET-AAS (n=10, Eq. 1).
Recovery% = (CA-CS)/CA×100 (Eq.1)
Fig. 1. The DIL-μ-SPE procedure based on IL-MWCNTs for Pb and Ni extraction
76
3. Results and discussion
The lead and nickel were extracted and determined
based on the IL-MWCNTs nanostructures which
characterized by scanning electron microscopy
(SEM), X-ray diffraction spectroscopy (XRD), and
Fourier transform infrared spectroscopy (FT-IR).
3.1. X-ray diffraction spectroscopy (XRD)
The powder XRD patterns of pristine MWCNTs (a)
and [Apmim][PF6] immobilized on MWCNTs (b)
are shown in Figure 2. The XRD of the MWCNTs
and IL-MWCNTs were compared. The two
characteristic graphitic peaks, at a 2θ value (28°
and 45°) corresponding to the peaks of the (002)
and (100) planes of hexagonal graphite MWCNT,
respectively, are present in the XRD pattern of both
measured samples. As shown in Figure 2, after
functionalized of [Apmim][PF6] on MWCNTs, no
new peaks were seen, and the characteristic peaks
of MWCNTs didn’t change.
Table 2. The analytical features for determination lead and nickel
by DIL-μ-SPE procedure coupled to ET-AAS
Features Value Pb Value Ni
Working pH 7.5-8.5 8.0
Amount of Il-MWCNTs(mg) 18 20
Sample volume of serum (mL) 10 .0 10.0
Sample volume of urine, water (mL) 15.0 12.0
Volume of sample injection (µL) 20 20
Linear range for serum (μg L−1) 0.4-30 0.2-5.8
Mean RSD %, n=10 4.2 3.9
LOD for urine or serum (μg L−1) 0.1 0.05
Enrichment factor for urine or serum 5.1 24.7
Volume and concentration of HNO30.2 mL, 0.3 M 0.2 mL, 0.2 M
Shaking/Centrifuging time 6.0 min, 4.0 min 6.0 min, 4.0 min
Correlation coefcient R2 = 0.9997 R2 = 0.9995
Fig. 2. The XRD of a) MWCNTs and b) IL-MWCNTs
Anal. Methods Environ. Chem. J. 4 (2) (2021) 72-85
77
3.2. Field emission scanning electron
microscopy (FE-SEM)
FE-SEM images of [Apmim][PF6] immobilized
on MWCNTs are shown in Figure 3. It showed
that the nanotubes have previous form and save
their nature as MWCNTs. Due to FE-SEM images
with different scale bars, a clear change in the
morphology of [Apmim][PF6] immobilized on
MWCNTs were seen that showed the ionic liquid
has been immobilized on the MWCNTs. The FE-
SEM showed that, the IL-MWCNTs have nano size
between 20-60 nm.
3.3. Fourier transform infrared spectroscopy
(FT-IR)
The FT-IR spectra of [Apmim][PF6]-MWCNTs
are shown in Figure 4. This FTIR spectrum
showed that the oxidation and covalently bond of
the pristine MWCNTs. The peak of 1717 cm-1 is
showed to the carbonyl bond (CO) due to oxidation
functionalities. Also, the peak at 3437-3439 cm-1
was assigned to the stretching of O-H groups on
the inner surface of oxidized MWCNTs. The
supporting of the aminopropylsilane group on OH
by treatment with APTMS was conrmed by the
appearance of a sharp peak at around 1094 cm-1
which is attributed to the O-Si-O bond constructed
between MWCNTs and ionic liquid moieties. The
IR peak at 2922 and 2854 cm-1 were related to
asymmetric and symmetric vibration absorptions,
respectively, for the aliphatic CH2 groups (C–H)
of chlorosilane coupling agent and butyl chain of
[Apmim][PF6].
3.4. Optimization of DIL-μ-SPE procedure
The DIL-μ-SPE procedure was used based on IL-
MWCNTs as a new adsorbent for determination
lead and nickel in human urine and serum samples.
High efcient recoveries, low RSD / LOD and
variable linear ranges were obtained by optimizing
of parameters such as, pH, amount of IL-MWCNTs,
HNO3 volume and concentration, the urine/
serum volume, and the capacity of adsorption for
extraction of Pb and Ni ions in human biological
samples.
3.4.1.The pH optimization
The pH of urine and serum sample has a main
role for adsorption of lead and nickel ions on
IL-MWCNTs by DIL-μ-SPE procedure. The
effect of pH range on the extraction of Pb and
Ni with adsorbent was studied for Ni and Pb
concentration between 0.2-5.5 µg L-1 and 0.4-30
µg L-1, respectively (Fig. 5). Based on results, the
recovery for Ni (II) and Pb(II) ions were increased
at pH range of 8.0 more than 96%. Also, the
extraction recoveries decreased at pH more than
8.5 and less than 7. So, the pH of 8 was selected
Fig. 3 . FE-SEM images of [Apmim][PF6] immobilized on MWCNTs
Nickel and Lead determination by[Apmim][PF6]-MWCNTs Arezou Lari et al
78
adsorption mechanism on the IL-MWCNTs was
achieved based on deprotonated amine groups
(Pb2+/Ni2+…..-NH2
charged of metals in optimized pH. At lower
pH, the surface of IL-MWCNTs have positively
charged due to the H+ protonation. Therefore, the
charge law between Pb2+/Ni2+and positively charged
of +NH2 of IL. Moreover, at pH of 8.0, the NH2
group of IL had negative charge (-) and caused to
increase adsorption adsorbent. The results showed,
high recovery for extraction Pb /Ni were achieved
was obtained about 30% in low pH as physically
adsorption.
Fig.4. The FT-IR spectra of IL-MWCNTs
Fig. 5.
Anal. Methods Environ. Chem. J. 4 (2) (2021) 72-85
79
Nickel and Lead determination by[Apmim][PF6]-MWCNTs Arezou Lari et al
3.4.2. Optimization of amount of IL-MWCNTs
By the DIL-μ-SPE procedure, the amount of IL-
MWCNTs was optimized for extraction of Ni(II)
and Pb(II) in urine and serum samples. In this
study, the amount of 5-40 mg of IL-MWCNTs was
studied. The results showed that the 18 mg of IL-
MWCNTs had high extraction for Ni(II) and Pb(II)
in urine and serum samples in optimized conditions.
Therefore, 20 mg of IL-MWCNTs was selected
as optimal amount of IL-MWCNTs (Fig. 6). The
more amount of IL-MWCNTs had no effect on the
extraction recovery of Pb/Ni at pH=8.
3.4.3. Effect of eluent
The volume and concentration of eluents for lead
and nickel extraction in urine and serum samples
was studied. By the DIL-μ-SPE procedure, the
various mineral acids were selected as elution
phase for back extraction Pb(II) and Ni(II) from IL-
MWCNTs phase at low pH. At low pH, the covalent
bond between metal and amine group break down
and Ni/Pb ions release in liquid phase. The different
volumes from 100 to 500 µL and concentration
between 0.1-0.5 mol L-1 were used as eluent phase
(HCl, HNO3, H2SO4 and H3PO4) by the DIL-μ-SPE
method. The results showed that the 0.2 mol L-1 of
HNO3 (0.2 mL) had quantitatively back extracted
Pb/Ni ions from IL-MWCNTs (Figs. 7). So, the
HNO3 was used for further works.
3.4.4.Sample volume optimization
The sample volume affected on the recoveries of
Pb(II) and Ni(II) ions at pH=8. In this research,
the various sample volumes of urine and serum
from 1 to 20 mL were studied for Pb(II) and Ni(II)
extraction in presence of the concentration between
0.2-5.5 µg L-1 and 0.4-30 µg L-1 for nickel and
lead, respectively by the DIL-μ-SPE procedure.
The results showed, the high extraction recoveries
less than 12 mL and 15 mL for lead and nickel in
urine samples were obtained, respectively. Also,
the good recoveries less than 10 mL for lead and
nickel in serum samples was achieved. Moreover,
the extraction efciency Pb(II) and Ni(II) ions was
reduced by increasing more than 10 mL samples.
Therefore, 10 mL was used as the optimal sample
volume by proposed procedure (Fig. 8).
3.4.5.Time of extraction
The interaction of IL-MWCNTs with Pb(II) and
Ni(II) ions is main factor for extraction process
by DIL-μ-SPE procedure. So, the time dispersion
of the IL-MWCNTs for metal extraction in the
urine and serum samples were calculated. The high
interaction caused to increase the extraction of
metals in liquid phase. The effect of the ultrasonic
time was evaluated based on IL-MWCNTs
adsorbent at PH=8. The results showed, the
maximum recovery was obtained about 6.0 min.
3.5. Reusability and Adsorption capacity
The reusability of IL-MWCNTs for extraction
of with Pb(II) and Ni(II) ions was examined for
several analyses by the DIL-μ-SPE method. The
good recovery based on 19 times of extraction
and back extraction cycles was obtained for Pb(II)
and Ni(II) by IL-MWCNTs. Also, the absorption
capacities IL- MWCNTs and MWCNTs for Pb(II)
and Ni(II) extraction in urine and serum samples
were achieved based on amine group of IL and
surface area of MWCNTs. For this propose, 20
mg of IL-MWCNTs and MWCNTs were added to
10 mL of standard solution with concentration of
10 mg L-1 of Pb(II) and Ni(II) in batch system at
optimized pH. By results, the adsorption capacity
of MWCNTs and IL- MWCNTs for Ni(II) and
Pb(II) was found 21.4/26.7 mg g-1 and 149.3 / 162.5
mg g-1, respectively.
3.6. The effect of concomitant ions
The effect of interference ions on Pb(II) and
Ni(II) extraction was studied in human urine
and serum samples by DIL-μ-SPE procedure
(Table 3). In optimized conditions, the various
interfering ions in human biological samples was
added to 10 mL of Pb(II) and Ni(II) of standard
solution with concentration of 30 μg L-1 and 5.5
μg L-1, respectively. The results showed, the
main concomitant ions had no effect on the metal
extraction at pH=8. The IL-MWCNTs had good
80 Anal. Methods Environ. Chem. J. 4 (2) (2021) 72-85
Fig. 6.
Fig. 7. The effect of eluent for back-extraction of a) lead and b) nickel from IL-
81
Fig. 8. The effect of sample volume on lead and nickel extraction in urine and
blood samples by the DIL-μ-SPE procedure
extraction for Pb(II) and Ni(II). in present of
the interference ions. The ethical committee of
Semnan University confirmed the project
for determining metals in the different matrices
(ECSU, Project No. 8051127-01) with student
proposal number(IR-9228558001).
3.7. Real sample analysis
The Pb(II) and Ni(II) ions was determined in
urine and serum samples based on IL-MWCNTs
by the DIL-μ-SPE procedure coupled to ET-
AAS. By optimizing parameters, the means of 10
times determinations, for Pb(II) and Ni(II) ions
were calculated. The human urine and serum
samples were spiked with Pb(II) and Ni(II)
standard solutions for 0.4-30 μg L−1 and 0.2-5.8
μg L−1 at pH=8, respectively (Table 4 and 5).
The results showed us, the spiking real samples
Table 3. The effect of interference ions on Pb(II) and Ni(II) extraction in human urine
and serum samples by the DIL-μ-SPE procedure
Interfering Ions(CA)
Mean ratio
(CA/CPb(II); or CA/CNi(II) ) Recovery (%)
Pb(II) Ni(II) Pb(II) Ni(II)
Cr3+, As3+ 900 800 98.8 97.4
Zn2+, Cu2+ 750 600 97.2 98.5
Cd2+ 700 300 97.0 95.8
I-, Br-, F- , Cl-1200 1100 99.2 98.6
Al3+, V3+ 650 700 98.0 96.9
Na+, K+, Cl-,Ca2+, Mg2+ 900 800 97.5 97.1
Co2+, Mn2+ 600 800 99.1 97.7
Hg2+ 50 80 96.6 97.3
Ag+ 200 150 98.0 98.7
SCN- , S2O3
2-, CH3COO -, NO3
-800 900 97.6 99.4
Nickel and Lead determination by[Apmim][PF6]-MWCNTs Arezou Lari et al
82
has favorite accuracy and pricision for lead and
nickel analysis in difculty matrixes. The mean
extraction efciency of spiked urine and serum
samples for Pb(II) and Ni(II) ions were obtained
from 95.2% to 104.3% ( RSD% < 5%) for ten
samples. The spike samples demonstrated that
the proposed method have satisfactory results for
extraction and determination Pb(II) and Ni(II)
ions in human biological samples. In addition,
the Pb(II) and Ni(II) ions concentration in urine
and serum samples was mesured with ICP-MS
and compared to DIL-μ-SPE/ET-AAS procedure
Table 4. Validation of lead determination(Pb) based on spiking of human serum, blood, plasma
and urine samples by DIL-μ-SPE procedure
Human Sample* Spike (μg L-1)*Found (μg L-1) Recovery (%)
Blood --- 14.7 ± 0.6 ---
15 29.8 ± 1.3 100.6
Serum
--- 15.2 ± 0.7 ---
15 30.1 ± 1.4 99.3
Urine
--- 8.4 ± 0.3
10 18.2 ± 0.9 98.0
--- 5.5 ± 0.2 ---
Plasma 5.0 10.3 ± 0.5 96.2
*Mean of three determinations of samples ± condence interval (P = 0.95, n =10)
All samples volumes diluted with DW (1:10), Dilution factor =10
Table 5. Validation of nickel determination (Ni) based on spiking of human serum, blood, plasma
and urine samples by DIL-μ-SPE procedure
Human Sample* Spike (μg L-1)*Found (μg L-1)Recovery (%)
Blood ---
2.5
2.22 ± 0.12
4.63 ± 0.18
---
96.4
Serum ---
2.5
2.65 ± 0.11
5.27 ± 0.28
---
104.8
Urine ---
1.5
1.35 ± 0.06
2.84 ± 0.12
99.3
Plasma ---
0.5
0.52 ± 0.02
1.01 ± 0.05
---
98.0
*Mean of three determinations of samples ± condence interval (P = 0.95, n =10)
Table 6. Comparing of DIL-μ-SPE /ET-FAAS with ICP-MS method for mean concentration
of Pb and Ni in human samples (μg L-1)
Sample ICP-MS ICP-MS *IL-MWCNTs
/ET-AAS
*IL-MWCNTs /ET-
AAS
Pb Ni Pb Ni
Blood 29.56± 0.96 2.53 ± 0.04 28.82± 1.42 2.41 ± 0.11
Urine 18.13 ± 0.35 1.87± 0.03 17.49 ± 0.77 1.95 ± 0.09
Serum 27.48 ± 0.81 4.68 ± 0.08 27.06 ± 1.32 4.43 ± 0.23
*Mean of three determinations of samples ± condence interval (P = 0.95, N =10),
The lead samples diluted with DW (1:10)
Anal. Methods Environ. Chem. J. 4 (2) (2021) 72-85
83
(Table 6). The precision and accuracy of
results showed the validation of methodology
for the Pb(II)/ Ni(II) determination by IL-
MWCNTs adsorbent.
4. Conclusions
A simple and efficient method based on IL-
MWCNTs adsorbent was used for separation and
determination of nickel and lead in urine and serum
samples by ET-AAS. By the DIL-μ-SPE procedure,
high recovery and efficient extraction was obtained
at optimized conditions. The linear range and
working range for Ni(II) and Pb(II) was achieved
0.2-3.42 µg L-1/0.4-17.6 µg L-1 and 0.2-5.8 µg
L-1/0.4-30 µg L-1 for 10 mL of urine and serum
samples, respectively. The mean correlation
coefficient and enrichment factor for Ni(II) and
Pb(II) were obtained 0.9997/0.9995 and 24.7/5.1,
respectively. The NH2 group in IL-MWCNTs was
coordinated with Ni(II) and Pb(II) cations and
separated from liquid phase by centrifuging
process. The high adsorption capacities, recovery,
enrichment and favorite reusability caused to
consider the DIL-μ-SPE procedure as a new
methodology for nickel and lead extraction in
human samples with low LOD and RSD (>5%) in
optimized conditions. The validation methodology
based on spiking samples and ICP-MS analysis
showed, the DIL-μ-SPE method can be used as
applied techniques for Ni(II) and Pb(II)
determination in human samples.
5. Acknowledgements
The authors wish to thank Semnan University
Research Council, Semnan, Iran.
Student proposal number:IR-9228558001.
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