Research Article, Issue 1
Analytical Methods in Environmental Chemistry Journal
Journal home page: www.amecj.com/ir
AMECJ
------------------------
1. Introduction
Calcium is essential element for bones and teeth
in body. It is also important role in heart function,
blood clotting, and muscle functioning. Calcium
levels increase in patients with kidney disease.
Raised calcium levels cause headaches, nausea,
sore eyes, aching teeth, itchy skin, and confusion.
Calcium (Ca) as a mineral has important role in
human body such as; bones, teeth, and nerves. The
kidneys keep calcium at normal levels in blood.
Also, the vitamin D is important factor for calcium
balance in blood serum and kidneys help to activate
vitamin D. Chronic kidney disease (CKD) caused
to renal failure and hypercalcemia in human.
(Normal range: 84–102 mg/L or 2.2–2.5 mmol/L).
Hypercalcemia has a positive chronotropic
effect on decreasing of heart rate and a positive
inotropic effect on increasing of contractility [1,
2]. In CKD, the kidneys are not able to keep the
levels of calcium at healthy levels, start to failure
and increase parathyroid hormone. So, it is very
important that blood calcium level determined
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
Dispersive solid phase microextraction based on amine-
functionalized bimodal mesoporous silica nanoparticles for separation
and determination of calcium ions in chronic kidney disease
* E-mail: hamidshirkhanloo@gmail.com
https://doi.org/10.24200/amecj.v1.i01.37
A R T I C L E I N F O:
Received 4 Sep 2018
Revised form 15 Nov 2018
Accepted 27 Nov 2018
Available online 24 Dec 2018
Keywords:
Calcium
Amine-functionalized bimodal
mesoporous silica nanoparticles
Ionic liquid
Human Blood
Ultrasound assisted- dispersive
solid-liquid multiple phase
microextraction
A B S T R A C T
The ultrasound assisted- dispersive solid phase microextraction method (USA-SPME)
was used for in-vitro study on separation/extraction of calcium ions in human blood
of chronic kidney disease (CKD). In this procedure, amine-functionalized bimodal
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
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 7). The concentration of Ca (II) was determined by flame
atomic absorption spectrometry (F-AAS, N2O, C2H2) after back extraction remained
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
in human body and can be used for in vivo study on decreasing calcium concentration in
hypercalcemia patient with CKD. The capacity absorption of NH2- UVM7 in blood and
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
proposed method and previous methods showed us, the NH2-UVM7 as effectiveness
sorbent for decreasing calcium concentration level in blood of hypercalcemia patients.
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.
Calcium extraction in human blood by USA-SPME Sara Davari, et al
Analytical Methods in Environmental Chemistry Journal Vol 1(2018) 57-66
58 Analytical Methods in Environmental Chemistry Journal; Vol. 1 (2018)
correctly. In parathyroid surgery for removal of
glands, blood calcium and phosphate levels must
be checked [3-7]. Different techniques, including
spectrophotometry, flame atomic absorption
spectrometry (F-AAS), inductively coupled
plasma (ICP), inductively coupled plasma mass
spectrometry (ICP-MS), inductively coupled
plasma optical emission spectrometry (ICP-OES),
and other spectrometry methods were used for
determination calcium in human biological samples
[8-12]. In recent years, many methods have been
used for sample preparation in biological samples,
such as microwave digestion coupled with ICP-MS,
liquid liquid microextraction (LLME), micro solid
phase extraction (MSPE) based on nanomaterials,
and ionic liquid-solid phase extraction (IL-SPE)
for improving of metal extraction[13-16].
Nowadays, IL-SPE has efficient recovery for
metal extraction in blood samples. In addition,
many carbonaceous materials such as activated
carbons [17], natural Adsorbents [ 18 ], fullerenes
[19], carbon nanotubes [20], and graphene [21,
22] have used for extraction/separation due to
their unique properties, such as nano particle
size, high surface area, and adsorption capacity
[23].
The mesoporous silicate nanoparticles (MSNPs)
have been used for a large reactants inside the pores.
The properties of MSNPs have simply accessed
to sulfur/amine/carboxylate functional groups on
surface structure. The Nano mesoporous silica
have high surface area and physical adsorption as
compared to MSM. The properties of MSNPs have
been investigated in metal extraction/separation in
biological and water samples by biotechnology. In
addition, MSNPs as adsorbents have large surface
area and high adsorption capacity for removal of
metals from human body such as urine, blood,
and plasma. The bimodal of mesoporous silica
nanoparticles (UVM7) are an interesting material
which can be considered as an special sorbent for
extraction of metals in blood samples[24-28]. In
this work, a new applied method based on NH2-
UVM7 as a nano adsorbent was used for calcium
extraction/separation in human blood samples by
USA-SPME. To the best of our knowledge, there
are no reports on decreasing calcium concentration
level in patient with renal failure and hypercalcemia.
2. Experimental
2.1. Reagents and Instrumental
The experiments were performed using a GBC-932
flame atomic absorption spectrometer equipped
with an auto-sampler instrument (F-AAS,
Dandenong, Victoria, Australia). A hollow cathode
lamp of calcium operated at a current of 15 mA
and a wavelength of 239.9 nm with a spectral
band width of 0.5 nm and deuterium background
corrector was applied (100-760 mg L-1 ). Chemical
interferences were seen for air acetylene for calcium
determination. For improving of interferences
strontium/lanthanum (2000 mgL-1) was added to
solution samples. All analytical grade of reagents
such as HNO3, Hcl, H2SO43, NaOH, buffers,
lanthanum solution (0.5 % ), tetraethyl ortho-
silicate, triethanolamine , cetyltrimethylammonium
bromide and triethoxysililpropylamine were
purchased from Merck Company (Germany). In a
1000 mL volumetric flask, add 50 mL deionized
water to 1.249 g anhydrous calcium carbonate
(CaCO3). Dissolve by adding dropwise 10 mL
concentrated hydrochloric acid (HCl). Dilute to
1 liter with deionized water. This standard stock
solution is 1000 mg Ca2+/L.
2.2. Synthesis of NH2-UVM7
The general procedure for synthesis of bimodal
mesoporous silica nanoparticle (UVM7) is the atrane
route, in which the presence of the polyalcohol
is the key to balancing the hydrolysis and
condensation reaction rates. In a typical synthesis,
TEOS (tetraethyl ortho-silicate) was added to
predetermine amounts of TEAH3 (triethanolamine).
The solution was heated up to 140 °C under
59
Calcium extraction in human blood by USA-SPME Sara Davari, et al
vigorous stirring. After cooling down to 90 °C,
CTAB (cetyltrimethylammonium bromide) was
added to this solution. For the functionalization
of calcined UVM7 with amine groups, 1.2 g of
triethoxysililpropylamine (C9H23NO3Si) and 2 g of
calcined UVM7 were added to appropriate amount
of toluene and refluxed for 24 h at 80 °C [14]. The
amine-functionalized bimodal mesoporous silica
nanoparticle (NH2-UVM7) was used for extraction
calcium ions from blood and serum samples.
2.3. Human Sample preparation
For sample preparation of blood/serum samples,
only 0.2 mL of samples diluted with DW up to 10
mL and used as real sample. The people of this
study selected in two groups: the biological samples
from normal men (control groups, 20 N) and renal
failure with hypercalcemia as a subject men (n=20).
The subject and control groups was selected from
men which was matched from people of the same
age. For sampling, all glass tubes were washed
with a 1.0 mol L-1 of HNO3 solution for at least
24 h and thoroughly rinsed 15 times with ultrapure
water before we use. The calcium concentrations
in healthy human such as, whole blood / serum
have a range from 8.4 to 10.2 mg dL-1. Even minor
contamination at any stage of sampling, sample
storage and handling, or analysis has the potential
to affect the accuracy of the results. In this study,
only 0.2 mL of blood/serum samples were collected
from dialysis patients and healthy matched controls
which were aged between 30 to 60 years. Separate
and disposable sterilized plastic syringes were
used for human blood sampling. Based on world
medical association declaration of Helsinki and
recommendations guiding physicians in biomedical
research and human Laboratory, the sample storage
and blood/urine sampling was prepared based on
principles of Helsinki law and absolutely protect
the life and health of the human subject. [29]. For
heparin liquid (free Ca, Germany) is added to 10
mL of sample by auto sampler and used 0.2 mL
for proposed procedure. By proposed method, the
analysis of blood samples can be obtained with
minimum of sample (0.2 mL) which was diluted by
DW up to 10 mL(DF=50). The human blood/urine
sample was maintained at –20 °C in a cleaned glass
tube without any reagents.
2.4. Characterizations of NH2-UVM7
The SEM was performed to illustrate the
morphology and particle size distribution of the
calcined NH2- UVM7. TEM image also illustrates
Fig. 1a. SEM of NH2-UVM7Fig. 1b. TEM of NH2-UVM7
60 Analytical Methods in Environmental Chemistry Journal; Vol. 1 (2018)
pore structure of NH2- UVM7 (Fig 1a and 1b).
XRD patterns of calcined UVM7 and NH2-UVM7
are shown in figure 2. There are three resolved
diffraction peaks in XRD patterns of NH2-UVM7
and UVM7, which can be indexed as the (100),
(110), (200) and (210) reflections associated
with hexagonal symmetry (Fig.2). The nitrogen
adsorption-desorption isotherms of UVM7 and
NH2-UVM7 were determined and displayed. The
corresponding isotherm of both samples displays two
distinct regions at medium and high relative pressure
which can be attributed to the presence of bimodal
pore system. The first is related to the presence of
small mesopores (IUPAC clacification), and the
second is related to the large mesopores (Fig.3).
2.5. General procedure
In this procedure, 10 mL of standard solution
and human blood /serum sample containing
calcium ions was used for extraction/separation of
calcium. The pH was adjusted to 7.5 with buffer
solutions. The amine group of NH2-UVM7 (5 mg)
as a complexing agent was dispersed in 1-Butyl-
4-methylpyridinium hexafluorophosphate [BMPy]
[PF6] (IL/Ac, 0.2 mL) and injected to human serum
samples for separation/extraction of Ca ions. The
solution place in ultrasound bath for 5 min and Ca2+
were complexed and efficient preconcentrated/
extraction by amine group of NH2-UVM7 at
optimized pH. After shaking, the sample was
centrifuged for 5 min and S/IL/Ac settled down in
bottom of tube, which was extracted Ca (II) ions by
binding to amine group ([Ca]2+ NH2 7).
Finally, the settled phase was back extracted by 0.5
mL of HNO3 (0.5 M), diluted up to 1 mL with DW
and determined by F-AAS. In addition in 1-Butyl-
4-methylpyridinium hexafluorophosphate [BMPy]
[PF6] (IL/Ac, 0.2 mL) can be extracted calcium
from blood samples up to 6.8% (Fig.4). Extraction
conditions of calcium with proposed method was
shown in table 1.
4. Results and Discussions:
4.1. Effect of pH
In this work, the influence of sample pH on
absorption of Ca (II) has been investigated using
different pH from 2 to 12 for 10-75 mg L of
calcium standard and 0.2 mL of blood samples.
Fig. 2. XRD of UVM7 and NH2-UVM7
61
Calcium extraction in human blood by USA-SPME Sara Davari, et al
The buffer were used for adjusting between pH=7
to 7.7. The complexation was strongly conditioned
by the pH of solutions and subsequently affects
extraction efficiency of the complex. The result
shows that the highest extraction efficiency for Ca
(II) was achieved from pH 7.5 (Fig. 5).
4.2. Effect of sample volume
Sample volume one of the most important
parameters to be studied. The effect of sample
volume was examined in the range of 1-50 mL for
10-50 mg L of Ca (II). Quantitative extraction
was observed between 1 - 15 mL. At higher
Fig. 3. The isotherms of UVM7 and NH2-UVM7
Table 1. Extraction conditions of calcium with proposed method
Parameter Value
Working pH 7.50
Amount of NH2-UVM75.00 mg
Sample volume of blood and serum 0.20 mL
Volume of sample injection 1.00 mL
working range (blood)
Linear range (Urine)
Intra-day precision (RSD %, n=10)
Inter-day precision (RSD %, n=10)
9.80-75.90 mg L-1
10- 50 mg L-1
3.60
4.20
Limit of detection of blood (LOD) 3.00 mg L-1
Preconcentration factor blood (PF) 10.20
Buffer concentration 0.03 mol L-1
Volume and concentration of back-extraction solvent (HNO3)-1
Correlation coefficient R2 = 0.9995
Ionic liquid/acetone 0.20 mL
62 Analytical Methods in Environmental Chemistry Journal; Vol. 1 (2018)
volumes the recoveries are decreased. Therefore, a
sample volume of 10 mL was selected for further
experiments of USA-SPME in standard and blood
samples (Fig. 6). As a consequence, the volume
required to back extraction of Ca (II) ions from
NH2-UVM7 depends on the strength of Ca (II)
retention and amount of NH2-UVM7 were used in
USA-SPME.
4.3. Effect of amount of adsorbent
In optimized conditions, 0.2 mL of blood samples,
pH of 7.5 for 10 mL of sample volume, the
effect of amount of sorbent was evaluated. It was
observed that extraction efficiency of the system
was remarkably affected by NH2-UVM7 amount in
blood samples, so it was examined within the range
of 1–15 mg. Quantitative extraction was observed
at higher than 4 mg by USA-SPME. Therefore, 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
nano-adsorbent (S/V) a very little amount of NH2-
UVM7 were used.
Fig. 4. The procedure of extraction/separation of calcium by USA-SPME
Fig. 5. The influence of sample pH on absorption of Ca (II) by USA-SPME
63
Calcium extraction in human blood by USA-SPME Sara Davari, et al
4-4 Effect of matrix
FAAS is a very simple method with low interference
for determination calcium in human body. By USA-
SPME, the interference of some coexisting ions in
blood and serum samples on the recovery of Ca
(II) ions was evaluated for optimized parameters.
The interference of coexisting ions effected on
pre-concentration step by proposed method. The
typical ions in blood and serum samples such as
cofactors of Mg, Cu, Zn, Fe, Mn, Cr, Na, K, and
Co which was interfered on calcium extraction
were investigated. The proposed procedure was
performed using a 10 mL sample containing 10-
50 mg L-1 -1 of different
concentration of matrix ions. The tolerate amounts
of each ion were tested that caused less than 7% of
the absorbance alteration. In optimized conditions,
the ions such as, Zn2+, Cu2+, Cr3+, Co2+, Mn2+,
Mg2+, Na+, K+, Fe2+ and Mg2+ do not interfere to
lead extraction by USA-SPME procedure (less than
7%). On the other hand, tolerable concentration
ratio of interfering ions versus Ca(II) ions for
Ni2+, HCO3
-, SO4
2- and CO3
2-, NO3
- , PO4
3- , Br-,
Cl- , F- was less than 360 and 520, separately. The
tolerable concentration ratio of interfering ions
versus Ca(II) ions for Hg and Ag was obtained less
than 45. The results showed us, the most of the
probable concomitant cations and anions have no
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
64 Analytical Methods in Environmental Chemistry Journal; Vol. 1 (2018)
considerable effect on the recovery efficiencies of
lead ions (Table 2).
4.5 Method Validation
The USA-SPME method based on NH2-UVM7,
were applied to determine Ca (II) in water samples.
The spiked samples were prepared to demonstrate
the reliability of the method for determination of
Ca (II). The remaining aliquots were spiked with
increasing quantities of Ca (II) and then analyzed
by the proposed method (Table 3). The recoveries
of spiked samples are satisfactorily reasonable and
were confirmed by using the additional method,
which indicates the capability of the system in the
determination of Ca (II) in standard and human
blood samples (0.2 mL). Also, the results showed
that the Ca (II) concentrations in blood samples
ranged from 11.63- 15.17 mg L-1
µg L-1 in the renal failure subjects and control
samples, respectively (Table 4). The intra mean
concentration of Ca (II) in serum of hypercalcemia
subjects (12.45 ± 0.59 µg L-1) was significantly
higher than healthy men controls (8.95 ± 0.44 µg
L-1) (P< 0.001). Also, total value of calcium in blood
of hypercalcemia subjects is higher than the normal
groups which were recommended by standard
value of human biochemistry. The results showed
that the Ca (II) concentrations in blood samples of
hypercalcemia subjects (20N) were higher than in
controls groups. There is no correlation between
5. Conclusions:
In this method, NH2-UVM7 nano-particles were
Table 2. Effect interfering ions on the recovery of Ca (II) ions by USA-SPME procedure
Foreign Ions
Concentration ratio (Cinterferent ions/CCa
2+) Mean of Recovery (%)
Standard Blood serum Standard Blood Plasma
Zn2+, Cu2+, Cr3+, Co2+, Mn2+ 1100 950 900 97.2 95.1 96.8
Mg2+, Na+, K+, Fe2+, Mg2+ 1200 1000 800 98.4 97.1 99.5
CO3
2-, NO3
- , PO4
3- , Br-, Cl- , F-
700 520 470 97.7 98.2 98.9
Ni2+, HCO3
-, SO4
2- 450 360 320 96.2 95.0 97.3
Hg2+, Ag+60 45 40 95.4 96.2 95.8
Table 3. Validation of calcium determination with FAAS by Ca (II) standard addition in human blood and water
samples (mg L-1)
Recovery (%)Found *
AddedSample
---15.2± 0.6---
aBlood
98.029.8 ± 0.715.0
---19.4 ± 0.8---
aBlood
103.340.1 ± 1.720.0
---14.3 ± 0.6---
aBlood
96.628.8 ± 0.815.0
---6.3 ± 0.3---wastewater
96.011.1 ± 0.55.0
---2.2 ± 0.1---Water
1054.3 ± 0.32.0
---10.6 ± 0.1---Waste water
97.020.3 ± 0.110.0
* =5)
a 0.2 mL of blood samples diluted with DW up to 10 mL (DF:50)
65
Calcium extraction in human blood by USA-SPME Sara Davari, et al
used as a solid phase for extraction and separation
of Ca (II) by USA-SPME. The developed
method has the advantages of simplicity, relative
selectivity, and high preconcentraion factor for Ca
(II). A small amount of adsorbent, low volume of
sample (0.2 mL) is employed in this procedure. The
determination of Ca (II) in blood and environmental
samples was successfully performed. The LOD,
preconcentration factor, working range, and
dilution factor for human samples was obtained 3.0
mg L-1, 10.2, 9.8-75.9 mg L-1 and 50 respectively.
6. Acknowledgment
The authors are thankful to the Iranian Petroleum
Industry Health Research Institute (IPIHRI) , PIHO
and IAUPS for preparation blood samples based
on the world medical association declaration of
Helsinki (R.IAU.SN.1396.944000980)
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Hypercalcemia Men (n=20) Healthy Men (n=20) Hypercalcemia
Intra-day Inter day Intra-day Inter day rP value
Serum 12.45 ± 0.59 12.62 ± 0.64 8.95 ± 0.44 9.08 ± 0.51 0.113 <0.001
Plasma 7.94 ± 0.46 8.02 ± 0.52 6.32 ± 0.32 6.53 ± 0.48 0.102 <0.001
Blood 13.04 ± 0.63 13. 27 ± 0.68 10.06 ± 0.48 9.87 ± 0.55 0.117 <0.001
P < 0.001
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b3
