Analytical Methods in Environmental Chemistry Journal Vol 1(2018) 57-66
Research Article, Issue 1
Analytical Methods in Environmental Chemistry Journal
Journal home page:
Dispersive solid phase microextraction based on amine-
functionalized bimodal mesoporous silica nanoparticles for separation
and determination of calcium ions in chronic kidney disease
Sara Davari a, Farnaz Hosseini a, and Hamid Shirkhanloo b,*
a Islamic Azad University of Pharmaceutical Sciences (IAUPS), Medical Nano Technology Tehran, Iran
b Research Institute of Petroleum Industry (RIPI), West Entrance Blvd., Olympic Village, P.O. Box: 14857-33111, Tehran, Iran
A R T I C L E I N F O:
The ultrasound assisted- dispersive solid phase microextraction method (USA-SPME)
Received 4 Sep 2018
was used for in-vitro study on separation/extraction of calcium ions in human blood
Revised form 15 Nov 2018
of chronic kidney disease (CKD). In this procedure, amine-functionalized bimodal
Accepted 27 Nov 2018
mesoporous silica nanoparticle (NH2-UVM7) as a solid phase was used for in-vitro
separation/extraction of calcium from blood/serum samples. Moreover, a mixture of
Available online 24 Dec 2018
NH2-UVM7 with ionic liquid and acetone (S/IL/Ac) was added to serum/blood sample
containing of Ca (II) at pH of 7.3. After ultrasonic bath and centrifuging, NH2-UVM7/
IL settled down in bottom of tube, which was extracted Ca (II) ions by binding to amine
group ([Ca]2+ →: NH2 ─ UVM7). The concentration of Ca (II) was determined by flame
) after back extraction remained
atomic absorption spectrometry (F-AAS, N2O, C2H2
adsorbent in IL by 0.5 mL of HNO3 (0.5 M). The results showed us, the NH2-UVM7 is
a powerful adsorbent for decreasing and controlling of high level calcium concentration
Amine-functionalized bimodal
in human body and can be used for in vivo study on decreasing calcium concentration in
mesoporous silica nanoparticles
hypercalcemia patient with CKD. The capacity absorption of NH2- UVM7 in blood and
Ionic liquid
water samples was obtained 258.5 mg g-1 and 267.2 mg g-1 at room temperature (25oC). The
characterization of NH2-UVM7 (SEM, TEM, FTIR and XRD) and comparisons between
Human Blood
proposed method and previous methods showed us, the NH2-UVM7 as effectiveness
Ultrasound assisted- dispersive
sorbent for decreasing calcium concentration level in blood of hypercalcemia patients.
solid-liquid multiple phase
Validation of methodology was confirmed using standard reference material (NIST,
SRM). Finally, the LOD and %RSD was obtained 3.0 mg L-1 and 3.6, respectively.
1. Introduction
Also, the vitamin D is important factor for calcium
Calcium is essential element for bones and teeth
balance in blood serum and kidneys help to activate
in body. It is also important role in heart function,
vitamin D. Chronic kidney disease (CKD) caused
blood clotting, and muscle functioning. Calcium
to renal failure and hypercalcemia in human.
levels increase in patients with kidney disease.
(Normal range: 84-102 mg/L or 2.2-2.5 mmol/L).
Raised calcium levels cause headaches, nausea,
Hypercalcemia has a positive chronotropic
sore eyes, aching teeth, itchy skin, and confusion.
effect on decreasing of heart rate and a positive
Calcium (Ca) as a mineral has important role in
inotropic effect on increasing of contractility [1,
human body such as; bones, teeth, and nerves. The
2]. In CKD, the kidneys are not able to keep the
kidneys keep calcium at normal levels in blood.
levels of calcium at healthy levels, start to failure
and increase parathyroid hormone. So, it is very
* E-mail:
important that blood calcium level determined
Analytical Methods in Environmental Chemistry Journal; Vol. 1 (2018)
correctly. In parathyroid surgery for removal of
this work, a new applied method based on NH2-
glands, blood calcium and phosphate levels must
UVM7 as a nano adsorbent was used for calcium
be checked [3-7]. Different techniques, including
extraction/separation in human blood samples by
spectrophotometry, flame atomic absorption
USA-SPME. To the best of our knowledge, there
(F-AAS), inductively coupled
are no reports on decreasing calcium concentration
plasma (ICP), inductively coupled plasma mass
level in patient with renal failure and hypercalcemia.
(ICP-MS), inductively coupled
plasma optical emission spectrometry (ICP-OES),
2. Experimental
and other spectrometry methods were used for
2.1. Reagents and Instrumental
determination calcium in human biological samples
The experiments were performed using a GBC-932
[8-12]. In recent years, many methods have been
flame atomic absorption spectrometer equipped
used for sample preparation in biological samples,
with an auto-sampler instrument
such as microwave digestion coupled with ICP-MS,
Dandenong, Victoria, Australia). A hollow cathode
liquid liquid microextraction (LLME), micro solid
lamp of calcium operated at a current of 15 mA
phase extraction (MSPE) based on nanomaterials,
and a wavelength of 239.9 nm with a spectral
and ionic liquid-solid phase extraction (IL-SPE)
band width of 0.5 nm and deuterium background
for improving of metal extraction[13-16].
corrector was applied (100-760 mg L-1 ). Chemical
Nowadays, IL-SPE has efficient recovery for
interferences were seen for air acetylene for calcium
metal extraction in blood samples. In addition,
determination. For improving of interferences
many carbonaceous materials such as activated
strontium/lanthanum (2000 mgL-1) was added to
carbons [17], natural Adsorbents [ 18 ], fullerenes
solution samples. All analytical grade of reagents
[19], carbon nanotubes [20], and graphene [21,
such as HNO3, Hcl, H2SO43, NaOH, buffers,
22] have used for extraction/separation due to
lanthanum solution
% ), tetraethyl ortho-
their unique properties, such as nano particle
silicate, triethanolamine , cetyltrimethylammonium
size, high surface area, and adsorption capacity
bromide and triethoxysililpropylamine were
purchased from Merck Company (Germany). In a
The mesoporous silicate nanoparticles (MSNPs)
1000 mL volumetric flask, add 50 mL deionized
have been used for a large reactants inside the pores.
water to
1.249 g anhydrous calcium carbonate
The properties of MSNPs have simply accessed
(CaCO3). Dissolve by adding dropwise 10 mL
to sulfur/amine/carboxylate functional groups on
concentrated hydrochloric acid (HCl). Dilute to
surface structure. The Nano mesoporous silica
1 liter with deionized water. This standard stock
have high surface area and physical adsorption as
solution is 1000 mg Ca2+/L.
compared to MSM. The properties of MSNPs have
been investigated in metal extraction/separation in
2.2. Synthesis of NH2-UVM7
biological and water samples by biotechnology. In
The general procedure for synthesis of bimodal
addition, MSNPs as adsorbents have large surface
mesoporous silica nanoparticle (UVM7) is the atrane
area and high adsorption capacity for removal of
route, in which the presence of the polyalcohol
metals from human body such as urine, blood,
is the key to balancing the hydrolysis and
and plasma. The bimodal of mesoporous silica
condensation reaction rates. In a typical synthesis,
nanoparticles (UVM7) are an interesting material
TEOS (tetraethyl ortho-silicate) was added to
which can be considered as an special sorbent for
predetermine amounts of TEAH3 (triethanolamine).
extraction of metals in blood samples[24-28]. In
The solution was heated up to
140 °C under
Calcium extraction in human blood by USA-SPME
Sara Davari, et al
vigorous stirring. After cooling down to 90 °C,
storage and handling, or analysis has the potential
CTAB (cetyltrimethylammonium bromide) was
to affect the accuracy of the results. In this study,
added to this solution. For the functionalization
only 0.2 mL of blood/serum samples were collected
of calcined UVM7 with amine groups, 1.2 g of
from dialysis patients and healthy matched controls
triethoxysililpropylamine (C9H23NO3Si) and 2 g of
which were aged between 30 to 60 years. Separate
calcined UVM7 were added to appropriate amount
and disposable sterilized plastic syringes were
of toluene and refluxed for 24 h at 80 °C [14]. The
used for human blood sampling. Based on world
amine-functionalized bimodal mesoporous silica
medical association declaration of Helsinki and
nanoparticle (NH2-UVM7) was used for extraction
recommendations guiding physicians in biomedical
calcium ions from blood and serum samples.
research and human Laboratory, the sample storage
and blood/urine sampling was prepared based on
2.3. Human Sample preparation
principles of Helsinki law and absolutely protect
For sample preparation of blood/serum samples,
the life and health of the human subject. [29]. For
only 0.2 mL of samples diluted with DW up to 10
analysis of whole blood samples, 10 μL of pure
mL and used as real sample. The people of this
heparin liquid (free Ca, Germany) is added to 10
study selected in two groups: the biological samples
mL of sample by auto sampler and used 0.2 mL
from normal men (control groups, 20 N) and renal
for proposed procedure. By proposed method, the
failure with hypercalcemia as a subject men (n=20).
analysis of blood samples can be obtained with
The subject and control groups was selected from
minimum of sample (0.2 mL) which was diluted by
men which was matched from people of the same
DW up to 10 mL(DF=50). The human blood/urine
age. For sampling, all glass tubes were washed
sample was maintained at -20 °C in a cleaned glass
with a 1.0 mol L-1 of HNO3 solution for at least
tube without any reagents.
24 h and thoroughly rinsed 15 times with ultrapure
water before we use. The calcium concentrations
2.4. Characterizations of NH2-UVM7
in healthy human such as, whole blood / serum
The SEM was performed to illustrate the
have a range from 8.4 to 10.2 mg dL-1. Even minor
morphology and particle size distribution of the
contamination at any stage of sampling, sample
calcined NH2- UVM7. TEM image also illustrates
Fig. 1a. SEM of NH2-UVM7
Fig. 1b. TEM of NH2-UVM7
Analytical Methods in Environmental Chemistry Journal; Vol. 1 (2018)
Fig. 2. XRD of UVM
and NH2-UVM7
pore structure of NH2- UVM7 (Fig 1a and 1b).
[PF6] (IL/Ac, 0.2 mL) and injected to human serum
XRD patterns of calcined UVM7 and NH2-UVM7
samples for separation/extraction of Ca ions. The
are shown in figure 2. There are three resolved
solution place in ultrasound bath for 5 min and Ca2+
diffraction peaks in XRD patterns of NH2-UVM7
were complexed and efficient preconcentrated/
and UVM7, which can be indexed as the (100),
extraction by amine group of NH2-UVM7 at
(200) and
(210) reflections associated
optimized pH. After shaking, the sample was
with hexagonal symmetry (Fig.2). The nitrogen
centrifuged for 5 min and S/IL/Ac settled down in
adsorption-desorption isotherms of UVM7 and
bottom of tube, which was extracted Ca (II) ions by
NH2-UVM7 were determined and displayed. The
binding to amine group ([Ca]2+ →: NH2 ─ UVM7).
corresponding isotherm of both samples displays two
Finally, the settled phase was back extracted by 0.5
distinct regions at medium and high relative pressure
mL of HNO3 (0.5 M), diluted up to 1 mL with DW
which can be attributed to the presence of bimodal
and determined by F-AAS. In addition in 1-Butyl-
pore system. The first is related to the presence of
4-methylpyridinium hexafluorophosphate [BMPy]
small mesopores
(IUPAC clacification), and the
[PF6] (IL/Ac, 0.2 mL) can be extracted calcium
second is related to the large mesopores (Fig.3).
from blood samples up to 6.8% (Fig.4). Extraction
conditions of calcium with proposed method was
2.5. General procedure
shown in table 1.
In this procedure,
10 mL of standard solution
and human blood
/serum sample containing
4. Results and Discussions:
calcium ions was used for extraction/separation of
4.1. Effect of pH
calcium. The pH was adjusted to 7.5 with buffer
In this work, the influence of sample pH on
solutions. The amine group of NH2-UVM7 (5 mg)
absorption of Ca (II) has been investigated using
as a complexing agent was dispersed in 1-Butyl-
different pH from 2 to 12 for 10-75 mg L−1 of
4-methylpyridinium hexafluorophosphate [BMPy]
calcium standard and 0.2 mL of blood samples.
Calcium extraction in human blood by USA-SPME
Sara Davari, et al
Fig. 3. The isotherms of UVM7 and NH2-UVM7
Table 1. Extraction conditions of calcium with proposed method
Working pH
Amount of NH2-UVM7
5.00 mg
Sample volume of blood and serum
0.20 mL
Volume of sample injection
1.00 mL
working range (blood)
9.80-75.90 mg L-1
Linear range (Urine)
10- 50 mg L-1
Intra-day precision (RSD %, n=10)
Inter-day precision (RSD %, n=10)
Limit of detection of blood (LOD)
3.00 mg L-1
Preconcentration factor blood (PF)
Buffer concentration
0.03 mol L-1
Volume and concentration of back-extraction solvent (HNO3)
500 μL and 0.50 mol L-1
Correlation coefficient
R2 = 0.9995
Ionic liquid/acetone
0.20 mL
The buffer were used for adjusting between pH=7
4.2. Effect of sample volume
to 7.7. The complexation was strongly conditioned
Sample volume one of the most
by the pH of solutions and subsequently affects
parameters to be studied. The effect
of sample
extraction efficiency of the complex. The result
volume was examined in the range of 1-50 mL for
shows that the highest extraction efficiency for Ca
10-50 mg L−1 of Ca (II). Quantitative extraction
(II) was achieved from pH 7.5 (Fig. 5).
was observed between
1 -
15 mL. At higher
Analytical Methods in Environmental Chemistry Journal; Vol. 1 (2018)
Fig. 4. The procedure of extraction/separation of calcium by USA-SPME
volumes the recoveries are decreased. Therefore, a
effect of amount of sorbent was evaluated. It was
sample volume of 10 mL was selected for further
observed that extraction efficiency of the system
experiments of USA-SPME in standard and blood
was remarkably affected by NH2-UVM7 amount in
samples (Fig. 6). As a consequence, the volume
blood samples, so it was examined within the range
required to back extraction of Ca (II) ions from
of 1-15 mg. Quantitative extraction was observed
NH2-UVM7 depends on the strength of Ca (II)
at higher than 4 mg by USA-SPME. Therefore, in
retention and amount of NH2-UVM7 were used in
order to achieve a suitable preconcentration, 5 mg
of NH2-UVM7 was chosen as optimum leading to a
final adsorbent (Fig. 7). Because of high surface of
4.3. Effect of amount of adsorbent
nano-adsorbent (S/V) a very little amount of NH2-
In optimized conditions, 0.2 mL of blood samples,
UVM7 were used.
pH of 7.5 for
10 mL of sample volume, the
Fig. 5. The influence of sample pH on absorption of Ca (II) by USA-SPME
Calcium extraction in human blood by USA-SPME
Sara Davari, et al
Fig. 6. The influence of sample volume on absorption of Ca (II) by USA-SPME
Fig. 7. The influence of amount of sorbent on absorption of Ca (II) by USA-SPME
4-4 Effect of matrix
concentration of matrix ions. The tolerate amounts
FAAS is a very simple method with low interference
of each ion were tested that caused less than 7% of
for determination calcium in human body. By USA-
the absorbance alteration. In optimized conditions,
SPME, the interference of some coexisting ions in
the ions such as, Zn2+, Cu2+, Cr3+, Co2+, Mn2+,
blood and serum samples on the recovery of Ca
Mg2+, Na+, K+, Fe2+ and Mg2+ do not interfere to
(II) ions was evaluated for optimized parameters.
lead extraction by USA-SPME procedure (less than
The interference of coexisting ions effected on
7%). On the other hand, tolerable concentration
pre-concentration step by proposed method. The
ratio of interfering ions versus Ca(II) ions for
typical ions in blood and serum samples such as
Ni2+, HCO3-, SO42- and CO32-, NO3- , PO43- , Br-,
cofactors of Mg, Cu, Zn, Fe, Mn, Cr, Na, K, and
Cl- , F- was less than 360 and 520, separately. The
Co which was interfered on calcium extraction
tolerable concentration ratio of interfering ions
were investigated. The proposed procedure was
versus Ca(II) ions for Hg and Ag was obtained less
performed using a 10 mL sample containing 10-
than 45. The results showed us, the most of the
50 mg L-1 of analyte and 1─ 5 g L-1 of different
probable concomitant cations and anions have no
Analytical Methods in Environmental Chemistry Journal; Vol. 1 (2018)
Table 2. Effect interfering ions on the recovery of Ca (II) ions by USA-SPME procedure
Concentration ratio (Cinterferent ions/CCa2+)
Mean of Recovery (%)
Foreign Ions
serum Standard
Zn2+, Cu2+, Cr3+, Co2+, Mn2+
Mg2+, Na+, K+, Fe2+, Mg2+
Ni2+, HCO3-, SO42-
Hg2+, Ag+
considerable effect on the recovery efficiencies of
ranged from 11.63- 15.17 mg L-1 and 8.58 ─ 10.76
lead ions (Table 2).
µg L-1 in the renal failure subjects and control
samples, respectively (Table 4). The intra mean
4.5 Method Validation
concentration of Ca (II) in serum of hypercalcemia
The USA-SPME method based on NH2-UVM7,
subjects (12.45 ± 0.59 µg L-1) was significantly
were applied to determine Ca (II) in water samples.
higher than healthy men controls (8.95 ± 0.44 µg
The spiked samples were prepared to demonstrate
L-1) (P< 0.001). Also, total value of calcium in blood
the reliability of the method for determination of
of hypercalcemia subjects is higher than the normal
Ca (II). The remaining aliquots were spiked with
groups which were recommended by standard
increasing quantities of Ca (II) and then analyzed
value of human biochemistry. The results showed
by the proposed method (Table 3). The recoveries
that the Ca (II) concentrations in blood samples of
of spiked samples are satisfactorily reasonable and
hypercalcemia subjects (20N) were higher than in
were confirmed by using the additional method,
controls groups. There is no correlation between
which indicates the capability of the system in the
control and subject groups were achieved (r ≈ 0.1).
determination of Ca (II) in standard and human
blood samples (0.2 mL). Also, the results showed
5. Conclusions:
that the Ca (II) concentrations in blood samples
In this method, NH2-UVM7 nano-particles were
Table 3. Validation of calcium determination with FAAS by Ca (II) standard addition in human blood and water
samples (mg L-1)
Recovery (%)
15.2± 0.6
29.8 ± 0.7
19.4 ± 0.8
40.1 ± 1.7
14.3 ± 0.6
28.8 ± 0.8
6.3 ± 0.3
11.1 ± 0.5
2.2 ± 0.1
4.3 ± 0.3
Waste water
10.6 ± 0.1
20.3 ± 0.1
*Mean of three determinations ± confidence interval (P = 0.95, n =5)
a 0.2 mL of blood samples diluted with DW up to 10 mL (DF:50)
Calcium extraction in human blood by USA-SPME
Sara Davari, et al
Table 4. determination of calcium in serum, blood and urine by USA-SPME method (intra -day and inter day) (mg dL-1)
Hypercalcemia Men (n=20)
Healthy Men (n=20)
Inter day
Inter day
P value
12.45 ± 0.59
12.62 ± 0.64
8.95 ± 0.44
9.08 ± 0.51
7.94 ± 0.46
8.02 ± 0.52
6.32 ± 0.32
6.53 ± 0.48
13.04 ± 0.63
13. 27 ± 0.68
10.06 ± 0.48
9.87 ± 0.55
0.117 <0.001
*Correlations are based on Pearson coefficients (r). Statistical significance will be observed if P < 0.001
Mean of three determinations of samples ± confidence interval (P = 0.95, n =10)
used as a solid phase for extraction and separation
[6] M. Brini, D. Ottolini, T. Calì, E. Carafoli, Calcium in
of Ca
(II) by USA-SPME. The developed
Health and Disease: Interrelations between essential
method has the advantages of simplicity, relative
metal ions and human diseases, Metal ions in life
selectivity, and high preconcentraion factor for Ca
sciences, Chapter 4, Springer Netherlands (2013).
(II). A small amount of adsorbent, low volume of
[7] J. Lappe, P. Watson, D. Travers-Gustafson, Effect of
sample (0.2 mL) is employed in this procedure. The
vitamin D and calcium supplementation on cancer
determination of Ca (II) in blood and environmental
incidence in older women: a randomized clinical
samples was successfully performed. The LOD,
trial, JAMA, 317.12 (2017) 1234-1243.
[8] B. S. F. Alves, F. I. M. Carvalho, A.S. Cruz, K. G.
preconcentration factor, working range, and
F. Dantas, Determination of Ca, Mg, Na, and K in
dilution factor for human samples was obtained 3.0
biodiesel of oilseed from northern Brazil, Revista
mg L-1, 10.2, 9.8-75.9 mg L-1 and 50 respectively.
Virtual de Quimica, 10 (2018) 542-550.
[9] L. Poirier, J. Nelson, D. Leong, L. Berhane, P. Hajdu,
6. Acknowledgment
F. Lopez-Linares, Application of ICP-MS and ICP-
The authors are thankful to the Iranian Petroleum
OES on the determination of nickel, vanadium,
Industry Health Research Institute (IPIHRI) , PIHO
iron, and calcium in petroleum crude oils via direct
dilution, Energy and Fuels, 30 (2016) 3783-3790.
and IAUPS, Tehran, Iran, for their support for this
[10] B. Han, M. Ge, H. Zhao, Y. Yan, J. Zeng, T.
Zhang, W. Zhou, J. Zhang, J. Wang, C. Zhang,
Determination of serum calcium levels by 42Ca
7. References:
isotope dilution inductively coupled plasma mass
[1] K.M. Gallant, D.M. Spiegel, Calcium balance in
spectrometry, Clin. Chem. Lab. Med., 56 (2017)
chronic kidney disease, Curr. Osteoporos. Rep., 15
(2017) 214-221.
[11] Y. Yan, M. Ge, R. Ma, H. Zhao, D. Wang, C. Hu, et
[2]P.H.F. Gois, M. wolley, D. Ranganathan, A. C.
al, A candidate reference method for serum calcium
segura, Vitamin D deficiency in chronic kidney
measurement by inductively coupled plasma mass
Disease: recent evidence and controversies, Int .J.
spectrometry, Clin. Chim. Acta, 461 (2016) -141
Environ. Res. Public Health, 15 (2018) 1773-1780.
[3] P.H.F. Gois, D Ferreira, S. Olenski, A.C. Seguro,
[12] S. Li, J. Wang, Measurement of Calcium in human
Vitamin D and infectious diseases: simple bystander
serum by dynamic reaction cell and two-way ID-
or contributing factor, Nutrients,
9 (2017) 651.
ICP-MS, Chem. Anal. Meter., 24 (2015).
[4] G. Jean, J.C. Souberbielle, C. Chazot, Vitamin
[13] J. Płotka-Wasylka, M. Frankowski, V. Simeonov,
D in chronic kidney disease and dialysis
Ż. Polkowska, J. Namieśnik, Determination of
patients, Nutrients,
9 (2017) 328.
metals content in wine samples by inductively
[5] J. Blaine, M. Chonchol, M. Levi, Renal control
coupled plasma-mass spectrometry, Molecules, 23
of calcium, phosphate, and magnesium
(2018) 2886.
homeostasis, Clin. J. Am. Soc. Nephrol., 10 (2015)
Analytical Methods in Environmental Chemistry Journal; Vol. 1 (2018)
[14] H. Shirkhanloo, M. Ghazaghi, A. Rashidi, A. Vahid,
nanotechnol., 2 (2011) 110-118.
Arsenic speciation based on amine-functionalized
[25] X. Xue, F. Li, Removal of Cu (II) from aqueous
bimodal mesoporous silica nanoparticles by
solution by adsorption onto functionalized SBA-16
ultrasound assisted-dispersive solid-liquid multiple
mesoporous silica, Micropor. Mesopor. Mater., 116
phase microextraction, Microchem. J., 130 (2017)
(2008) 116-122.
[26] J. El Haskouri, J.M. Morales, D. Ortiz de Zarate,
[15] H. Zhang, Y. Yuan, Y. Sun, C. Niu, F. Qiao, H.
L. Fernández, J. Latorre, C. Guillem, A. Beltrán,
Yan, An ionic liquid-magnetic graphene composite
D. Beltrán, P. Amorós, Nanoparticulated silicas
for magnet dispersive solid-phase extraction of
with bimodal porosity: chemical control of the pore
triazine herbicides in surface water followed by
sizes, Chem., 47 (2008) 8267-8277.
high performance liquid chromatography, Analyst,
[27] J. Mo, L. Zhou, X. Li, Q. Li, L. Wang, Z. Wang,
143 (2018) 175-181.
On-line separation and pre-concentration on
[16] A.C. Sotolongo, E.M. Martinis, R.G. Wuilloud, An
a mesoporous silica-grafted graphene oxide
easily prepared graphene oxide-ionic liquid hybrid
adsorbent coupled with solution cathode glow
nanomaterial for micro-solid phase extraction and
discharge-atomic emission spectrometry for the
preconcentration of Hg in water samples, Anal.
determination of lead, Microchem. J., 130 (2017)
Method., 10.3 (2018) 338-346.
[17] I. García-Díaz, F. López, F. Alguacil, Carbon
[28] S. Bayir, A. Barras, R. Boukherroub, S. Szunerits,
Nanofibers: A New Adsorbent for Copper Removal
L. Raehm, S. Richeter, J.O. Durand, Mesoporous
from Wastewater, Metals, Metals, 8 (2018) 914.
silica nanoparticles in recent photodynamic therapy
[18] R. Pournima, M. Shrikant, A short overview: Heavy
applications, Photochem. Photobiol. Sci.,
metal toxicity, health hazards and their removal
(2018): 1651-1674.
technique by natural adsorbents, Inter. J. Curr. Eng.
[29] World medical association declaration of Helsinki,
Technol., 8 (2018) 400-406.
Ethical Principles for Medical Research Involving
[19] E. Ciotta, P. Prosposito, P. Tagliatesta, C.
Human Subjects, Adopted by the
18th WMA
Lorecchio, L. Stella, S. Kaciulis, P. Soltani, E.
General Assembly, Helsinki, Finland, June (1964).
Placidi, R. Pizzoferrato, Discriminating between
different heavy metal ions with fullerene-derived
nanoparticles, Sensors, 18 (2018) 1496.
[20] Z.A. Alothman, S.M. Wabaidur, Application of
carbon nanotubes in extraction and chromatographic
analysis: A review, Arab. J. Chem. (in press 2018).
[21] M. Rosillo Lopez, C.G. Salzmann, Highly
efficient heavy-metal extraction from water with
carboxylated graphene nanoflakes, RSC. Adv., 8
(2018) 11043-11050.
[22] K.C.M.S. Lima, A.C.F. Santos, R.N. Fernandes,
F.S. Damos, R.D, Luz, Development of a novel
sensor for isoniazid based on
dicyano-p-benzoquinone, Microchem. J.,
(2016) 226-234.
[23] D.R. Dreyer, S. Park, C.W. Bielawski, R.S. Ruoff,
The chemistry of graphene oxide, Chem. Soc. Rev.,
39 (2010) 228-240.
[24] J.P. Thielemann, F. Girgsdies, R. Schlögl, C. Hess,
Pore structure and surface area of silica SBA-15:
influence of washing and scale-up, Beilstein. j.