1. Introduction
Molybdenum as inorganic material belongs to
transition metal. Molybdenum (Mo) exists in
environment with different oxidation numbers and
complex compounds. The high concentration of
Mo has toxic effects in humans and cause to many
diseases in human body like central nervous system,
Anal. Method Environ. Chem. J. 3 (3) (2020) 54-64
Research Article, Issue 3
Analytical Methods in Environmental Chemistry Journal
Journal home page: www.amecj.com/ir
AMECJ
In-vitro speciation of molybdenum (II, VI) in human
biological samples based on thiol-functionalized mesoporous
silica nanoparticles and hexyl-methylimidazolium tris-
Roya Ashouri a,b and Seyed Alireza Hajiseyed Mirzahosseini b,*
aDepartment of Environmental science, Science and Research Branch, Islamic Azad University, Tehran, Iran
bDepartment of Environmental Engineering, Faculty of Natural Resources and Environment, Science and Research Branch,
Islamic Azad University, Tehran, Iran
ABSTRACT
Molybdenum (Mo) ions enter to human body from the diet or
drinking waters and have a potentially toxic effect on human. The
thiol-functionalized mesoporous silica nanoparticles (HS-MSNPs)
was used for determination and speciation of Mo (II, VI) in human
biological samples by dispersive ionic liquid-micro-solid phase
thiol group of MSNPs at pH 6 and 2, respectively and collected through
IL in bottom of conical tube by centrifuging. Then, the Mo(II,VI) ions
were back-extracted from HS-MSNPs with elent based on changing
Mo) was simply calculated by the summation of Mo(II) and Mo(VI)
content. In optimized conditions, the linear range (LR), the limit of
L
and
, respectively. In purposed study, a new analytical method
for rapid speciation and determination of trace amount of Mo (II, VI)
was used in human blood and serum samples. The developed method
was successfully validated by ICP-MS analysis.
Keywords:
Molybdenum, Speciation,
Human serum,
Ionic liquid,
Thiol-functionalized bimodal
Dispersive-ionic liquid-micro-solid
phase extraction
ARTICLE INFO:
mirzahosseini@gmail.com
5
------------------------
liver and renal disorder. Molybdenum has low
concentration in seawater and high concentrations
in kidney, liver, and adrenals of human . In human
body, the concentration of Mo in serum is almost
g L and depends on dietary intake. Normal
.
Normal whole blood concentrations are between
Lin exposed peoples . The, molybdate can be
chemically adsorbed onto positively charged iron,
aluminium or manganese oxides . Therefore,
high molybdenum intake causes a secondary
hypocuprosis . Molybdenum toxicity caused
to diarrhea, anorexia, graying of hair, anemia and
these symptoms are readily reversed by copper
supplementation. The tetrathiomolybdates interact
with copper and caused to the treatment of copper
disorders such as Wilson’s disease . The
intracellular pool of cysteine is relatively small
as compared to the glutathione (GSH) . By
oxidizing, cysteine is oxidized to cystine and so, the
cysteine in plasma has low concentration between
. The cells have different
transport for cysteine (Cys) and cystine by different
membrane carriers and both of them can be
reaction with Mo and complex with Mo as R-Mo
.
a metabolic disorder and cause to defects in the
biosynthesis of Moco leading to loss of activity
of Mo enzymes . Molybdenum has seen in
brain and can be measured in urine, blood, and
mitochondria and cytoplasm of cells. Mo helps
to involve the metabolism pathway of sulfate and
or
binds strongly to amino acids, enzymes
( , and xanthine
oxidase), metallothionein (MT), molybdenum
cofactor (Mo(VI), molybdopterin), cysteine
(Cys), proteins (Pr) and metabolized in the brain
and other tissues. So, the organic Mo(R-Mo) is
important in human body and must be determined
. Many developed methods included,
, the stripping voltammetry , the UV
visible spectrophotometer were used for
determination Mo in different matrixes such as
matrix in human blood samples, we have to use
the extraction techniques for preparation of human
blood samples. The ionic liquids (ILs) as an
organic salts have the various advantages such as
thermal stability, high viscosity and good solvent
for separation phase. The ILs as a green solvent
were used for extraction or separation ions from
liquid phases. Recently, the sample preparation
combined with controlled potential electrolysis
technique and solid phase extraction based
on inductively coupled plasma-optical emission
reported for
extraction Mo from samples.
In this study, the speciation of Mo(II) and Mo(VI)
in human blood samples was obtained based on HS-
used for separating and collecting of HS-MSNPs
adsorbent from liquid phase. In optimized
conditions, a simple, fast and sensitive procedure
was demonstrated for speciation and determination
of trace Mo(II) and Mo(VI) in human biological
samples.
2. Experimental
2.1. Instruments
Determination of Mo was performed with a GBC
nm slit) was used. The temperature programming
oC
o
Anal. Method Environ. Chem. J. 3 (3) (2020) 54-64
.
by a digital pH meter (PeakTech
for separation IL from solution. Long and short
bath with heating system has been designed for
performance, control, durability and reliability to
disperse nanoparticles in liquid phase. (Branson,
). The crystal
structure studies of the solids were carried out
diffractmeter, Netherland) with Cu-K radiation
source.
2.2. Reagents
grade were purchased from Merck (Darmstadt,
Germany). The ethanol, acetone and toluene all
solutions were prepared in ultra-pure deionized
Molybdenum (II) acetate dimer as di-molybdenum
was purchased
from Merck, Germany. The general procedure
for synthesis of thiol-functionalized bimodal
mesoporous silica nanoparticles (HS-MSNPs) was
-Butyl-
-methylimidazolium
from Sigma, Germany.
2.3. Synthesis of thiol functionalized MSNPs
The general procedure for synthesis of MSNPs
is the atrane route, in which the presence of the
polyalcohol is the key to balancing the hydrolysis and
condensation reaction rates
(CH22
to appropriate volume of toluene and then the
and water for many times. The thiol functionalized
MSNPs (HS- MSNPs) was created after drying at
o
2.4. Characterization
.
The scanning/ transmission electron microscopy
was obtained in this study. Scanning electron
was used for morphology and surface image
analysis of the sorbents. The nanoparticles size for
HS- MSNPs was examined by transmission electron
The X-ray diffraction (XRD) patterns continued
with the Shimadzu XRD which are designed with
the concept of provide solution to XRD analysis by
ease of use and versatility. Basic system with high
precision goniometer can be varied with optional
2.5. DIL-μ-SPE Procedure
aqueous solution containing Mo(II) and Mo(VI)
was used in optimum pH of 6 and 2 with buffer
solution, respectively before moved to centrifuge
-MSNPs
by a syringe into the sample solution. Then, the
sample was dispersed in solution by ultrasonic
W). Mo(II) and Mo(VI) species were extracted
and preconcentrated by HS-MSNPs at pH of 6
and 2, separately. The loaded sorbent (Mo—HS-
MSNPs) was collected with IL by centrifuging
Mo(VI) on HS-MSNPs/IL was back-extracted in
2+
for Mo6+) and concentration of Mo(II) and Mo(VI)
. lso, the
total Mo was calculated by the summation of
human blood and serum samples were achieved
by ratio of extracted Mo(II) or Mo(VI) in human
blood sample to standard solution as a matrix-
free solution which was shown in below equation.
3. Results and discussion
3.1. The XRD and FT-IR analysis
The XRD patterns of calcined HS-MSNPs and
MSNPs are shown in. There are three
resolved diffraction peaks in XRD patterns,
Fig. 1.
Fig.2. The XRD patterns of of MSNPs and HS- MSNPs
Anal. Method Environ. Chem. J. 3 (3) (2020) 54-64
silica wall of MSNPs, the main three diffraction
peaks are still clear and similar which means that
functionalization of HS on MSNPs did not had
worth effect on the structural order of MSNPs
and HS- MSNPs was shown in
2
cm was confirmed the SH group on the walls
of MSNPs.
3.2. SEM and TEM imaging
morphology and particle size distribution of the
, HS-
MSNPs has a highly porous morphology and the
mesoporous silica particles are in nanometer range
also illustrates the size and pore structure of HS-
, the mesoporous
Fig. 3.
Fig. 4.
are clearly visible in the silica nanoparticles and
particle size of the samples is in nanometer range
3.3. The pH and sample volume optimizations
speciation of Mo in human blood samples, the
pH must be studied and optimized. The pH effect
on quantitative recoveries of Mo(II) and Mo(VI)
ions by changing of the surface charge of the thiol
group on HS-MSNPs adsorbent as the negative or
positive charges which can attract with Mo(II) and
of Mo(II) and Mo(VI). The results showed
pH 2 and 6 was used as optimum pH for extraction
of Mo(II) and Mo(VI) ions from blood samples by
HS-MSNPs adsorbent
blood sample volume for extraction of Mo(II) and
Mo(VI) ions based on HS-MSNPs adsorbent was
was used for further study.
3.4. Speciation mechanism
The thiol functionalized mesoporous silica
nanoparticles (HS-MSNPS) can be adsorbed Mo(II)
and Mo(VI) ions from blood samples. The thiol
groups can be deprotonated (SH
and Mo(II) can be absorbed as a rule of opposite
charge at optimized pH. So, the interaction of HS
groups of sorbent with cationic form of Mo2+ was
thiol (SH2+
Mo(VI) anions adsorbed on HS-MSNPS by positive
charged of thiol group in human blood samples.
Therefore, the pH of 2 and 6 was selected as optimum
pH for extraction and speciation Mo(II) and Mo(VI)
3.5. Effect of the amount of adsorbent and ILs
In this work, the effect of HS-MSNPs mass on
the recoveries of Mo(II) and Mo(VI) ions was
investigated. So, the various amounts of HS-MSNPs
and optimized. The results showed us, the extraction
By same conditions, the recovery of extraction for
of HS-MSNPs were used or further works .
Fig. 5. The effect of pH on speciation of Mo(II) and Mo(VI) ions by HS-MSNPs adsorbent
Anal. Method Environ. Chem. J. 3 (3) (2020) 54-64
Moreover, the effect of kind and amount of ILs were
studied by proposed procedure. So, the different amount
optimum amount of IL for this work (Fig. 7).
3.6. Effect of matrix
The effect of interference ions concentration for
extraction of Mo(II) and Mo(VI) ions must be studied
interfering ions for the determination of Mo(II) and
Mo(VI) ions were investigated. The procedure was
of
Mo(II) and Mo(VI) ions with different concentration
. Based on
results, the interference ions in blood samples such
Fig. 7.
Fig. 6.
as Cu2+, Mn2+, Mg2+ , Zn2+
2-
-
do not interfere for extraction of Mo(II)/ Mo(VI)
ions under optimized conditions (Table 1).
3.7. Validation in real samples
samples were spiked to demonstrate the accuracy and
precision of the method for determination of Mo(II)
and Mo(VI) ions. The spiked samples is satisfactorily
using addition method (Table 2).
By procedure, the calibration curve for Mo(II) and
Blood Interfering ions (BII) Mean ratio
(CBII /C Mo)
Recovery (%)
Mo(II) Mo(VI) Mo(II) Mo(VI)
Mn2+, Cd2+,
Cr,
V
Ca2+, Mg2+
Na+, K+,
Zn2+, Cu2+
I- , Br--, Cl-
2-
2-
-
Ni2+, Co2+
Pb2+
Hg2+
Table 1. The effect of interferences ions on extraction of Mo(II) and Mo(VI) ions in blood
Sample
Added (μg L-1)Found (μg L-1) Recovery (%)
Mo (II) Mo(VI) Mo (II) Mo(VI) T-Mo Mo (II) Mo(VI)
----- ----- ----- -----
----- -----
----- -----
----- ----- ----- -----
Blood B ----- -----
-----
----- ----- ----- -----
Serum C ----- -----
-----
----- ----- ----- -----
Serum D ----- -----
-----
a
Table 2. Validation of methodology based on HS-MSNPs adsorbent for speciation of Mo(II) and Mo(VI)
ions in serum and blood samples by spiking to real samples
62 Anal. Method Environ. Chem. J. 3 (3) (2020) 54-64
, respectively. In addition,
the ICP-MS analysis was used for speciation of
Mo(II) and Mo(VI) ions in standard solutions
(Table 3)
for determination of total Mo(T-Mo) in human
accuracy and precision of proposed procedure
for determination and speciation of Mo(II) and
Mo(VI) ions in human blood samples (Table 4).
4. Conclusions
In this research, a simple, sensitive, accurate
and precise method was used to demonstrate the
separation /speciation and determination of trace
Mo(II) and Mo(VI) ions in human blood samples.
factors on extraction process such as pH and amount
of adsorbent and IL were optimized. The mean of
L, respectively
of total Mo in blood and serum samples were
comparable to ICP-MS technique. The adsorption
capacities of the HS-MSNPs and MSNPs for total
,
relative standard deviation
(RSD%) for speciation and determination of trace
Mo(II) and Mo(VI) ions in human blood samples was
samples and ICP-MS analysis in standard solution
or human blood samples.
5. Acknowledgment
The authors thank the Science and Research
Branch, Islamic Azad University. The doctoral
proposal was confirmed by the Committee of Azad
University (SN.IAU.SُRB.930543874).
6. References
in human whole blood of adult residents of
Table 3. Validation of results for determination of Mo(II) and Mo(VI) ions in standard solutions
Sample
CRM (μg L-1) Found a (μg L-1) Recovery (%)
Mo (II) Mo(VI) Mo (II) Mo(VI) Mo (II) Mo(VI)
Standard
Standard
a
Table 4. Validation of results for determination of total Mo(T-Mo) ions in blood and serum
Sample
ICP-MS (μg L-1)
T-Mo
aDIL-μ-SPE (μg L-1)
T-Mo
Recovery (%)
T-Mo
Blood Serum Blood Serum Blood Serum
Sample B
Sample C
a
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