Author’s Accepted Manuscript
Synthesis of an imprinted polymer for thedetermination of methylmercury in marine products
Roi Rodríguez-Fernández, Elena Peña-Vázquez,Pilar Bermejo-Barrera
PII: S0039-9140(15)30075-8DOI: http://dx.doi.org/10.1016/j.talanta.2015.06.028Reference: TAL15705
To appear in: Talanta
Received date: 19 December 2014Revised date: 9 June 2015Accepted date: 13 June 2015
Cite this article as: Roi Rodríguez-Fernández, Elena Peña-Vázquez and PilarBermejo-Barrera, Synthesis of an imprinted polymer for the determination ofmethylmercury in marine products, Talanta,http://dx.doi.org/10.1016/j.talanta.2015.06.028
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Synthesis of an imprinted polymer for the determination of methylmercury in
marine products
Roi Rodríguez-Fernández, Elena Peña-Vázquez and Pilar Bermejo-Barreraa,
*
Department of Analytical Chemistry, Nutrition and Bromatology, Faculty of Chemistry,
University of Santiago de Compostela, Avenida de las Ciencias s/n, E-15782, Santiago
de Compostela, Spain.
ABSTRACT
A molecularly imprinted polymer was synthesized using the precipitation method with
methylmercury chloride as the template, phenobarbital as ligand, methacrylic acid
(MMA) as monomer, and ethylene glycoldimethacrylate (EDMA) as cross-linking
agent. The MIP was characterized using elemental analysis, infrared spectroscopy,
energy dispersive X-ray fluorescence and scanning electron microscopy. The operating
conditions for solid phase extraction (SPE) were optimized in column mode (pH,
loading and elution flow rate using 1M thiourea in 1M HCl). The polymer was used for
analyzing the toluene extracts of two reference materials (BCR-463 and TORT-2) with
good accuracy.
Keywords. Methylmercury, molecularly imprinted polymer (MIP), SPE, HRCSAAS,
fish
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1.Introduction
The number of imprinted polymers developed for environmental remediation or solid
phase extraction (SPE) previous to mercury analysis, mainly in water, has increased
sharply in recent years. Most of these polymers were synthesized using Hg(II) as
template and complexing ligands to produce selective binding sites. The ligands usually
contained a sulfur donating atom such as methacryloyl-(L)-cysteine (MAC) [1],
aminothiol monomers [2,3], 1-(2-thiazolylazo)-2-naphthol [4],4-(2-thiazolyazo)
resorcinol (TAR) [5] and diphenylthiocarbazone [6,7]. Compounds containing amino
groups were also used for developing imprinted polymers for Hg(II) removal from
aqueous solutions or preconcentration: 3-isocyanatopropyltriethoxysilane (IPTS) [8]
bearing thymine (T) bases, diazoaminobenzene-vinylpyridine copolymers[9],
tetrakis(3-hydroxyphenyl)porphyrin[10] or a polyaminated chitosan derivative [11].
Other natural materials have been used as supports for ion imprinting and adsorption of
mercury (II), e.g. crop stalks [12] or cellulosic cotton fibers[13]. Monier and Abdel-
Latif [14] also synthesized ion-imprinted chelating fibers based on poly(ethylene
terephthalate) for selective removal of Hg2+.
The surface imprinting technique has been used because it provides good accessibility
to the analyte and low-mass transfer resistance [15]. Thus, several authors have
developed organic-inorganic hybrid materials using thiol-functionalized mesoporous
sorbents and methanesulfonic acid [16-18] or cetyltrimethylammonium bromide
(CTAB) as a second template to improve the efficiency of the polymer [19,20]. Dakova
et al. [21] used silica gel modified with 3-(trimethoxysilyl)propyl methacrylate (TSPM)
as supporting material to synthesize a core-shell type imprinted polymer. The outer
layer included methacrylic acid (MAA) as monomer and the complexes of Hg(II) with
pyrrolidine dithiocarbamate (PDC) or 1-(2-thiazolyazo)-2-naphthol (TAN) as templates.
The sorbent was used for the speciation of mercury in samples of wine, with or without
digestion. Najafi et al. [22] coated Fe3O4 magnetic nanoparticles with an ion-imprinting
polymer based on N-(pyridine-2-ylmethyl)ethenamine, and these particles were used for
the determination of low levels of Hg(II) in fish samples.
The imprinting technique was also used for the development of modified carbon
electrodes for Hg(II) [23-27], an optical sensor using 9-vinylcarbazole as fluorescent
probe [28] and imprinted photonic polymers [29, 30].
Even though the number of the studies appearing in the literature has increased sharply
in recent years, only a few studies deal with the development of imprinted polymers
and methylmercury as a template [31,32]. Bu�yu �ktiryaki et al.[31] used the dispersion
polymerization technique to synthesize imprinted beads that were used as SPE support
for the determination of methylmercury and mercury ions in LUTs (a non-defatted
lobster hepatopancreas certified reference material) and in several spiked synthetic
seawaters. The methylmercury-methacryloyl-(L)-cysteine (MM-MAC) complex was
used as monomer, and ethylene dimethacrylate (EDMA) was used as crosslinking agent.
Liu et al.[32] used precipitation polimerization to synthesize a methylmercury-
imprinted polymer with (4-ethenylphenyl)-4-formate-6-phenyl-2,2'-bipyridine,
divinylbenzene (DVB) as crosslinking agent and 2,2�-azobisisobutyronitrile (AIBN) as
initiator. They packed the polymer in columns and used it for the determination of
methylmercury in aqueous and biological samples (human hair).
Recently, an international global treaty to reduce emissions and release of mercury was
signed, but the amount of the element in the environment is still increasing [33]. The
European Food Safety Authority (EFSA) updated its scientific advice on mercury in
food in December 2012. A new Tolerably Weekly Intake (TWI) was established for
inorganic mercury (4 µg/kg body weight) and for methylmercury (1.3 µg/kg body
weight, expressed as mercury)[34]. Methylmercury is the predominant form of mercury
in seafood (fish and shellfish), and affects the development of the nervous system; this
is the reason why unborn children are the most vulnerable group, especially if the
mother consumes large amounts of fish. Inorganic mercury is less toxic and can also be
found in fish and seafood as well as ready-made meals. The Dietetic Products,
Nutrition and Allergy (NDA) Panel published in July 2014 a Scientific Opinion on
health benefits of seafood consumption in relation to health risks associated with
exposure to methylmercury[35]. Seafood is a source of essential nutrients such as
iodine, selenium, calcium, vitamins A and D, and n-3 long-chain polyunsaturated fatty
acids (n-3 LCPUFA). The Panel concluded that consumption of about 1-2 servings of
seafood per week and up to 3-4 servings per week during pregnancy has been associated
with lower risk of coronary heart disease mortality in adults and with better functional
neurodevelopment in children, compared to no consumption of seafood. Those amounts
agree with the current guidelines in most of the European countries that usually give
specific recommendations for toddlers, pregnant and lactating women, taking into
account the higher concentration of the contaminants in some species (e.g. swordfish,
dogfish, marlin, shark, ray or tuna).
The interaction between mercury and phenobarbital is well known because it was used
in some classical methods for fast analysis of barbiturates in blood [36], urine [37],
plasma and gastric contents [38]. In recent years, amobarbital imprinted microspheres
have been synthesized using methacrylic acid (MMA) and EDMA. They have been
used for the selective solid-phase extraction of phenobarbital from human urine and
medicines [39]. The objective of the present study is the development of a simple
procedure to synthesize a methylmercury imprinted polymer using phenobarbital as
ligand. The polymer has been characterized using different techniques. The operating
conditions were also studied and the polymer was used for the analysis of
methylmercury in two certified reference materials of marine products after an
extraction step with toluene.
2. Material and methods
2.1 Instrumentation
Mercury was analyzed using a High Resolution Continuum Source Atomic Absorption
Spectrometer (HRCSAAS) (Analytik Jena ContrAA 300 model, Jena, Germany),
equipped with a flow injection system to perform the vapor generation.
The polymer was synthesized using a roll and tilt mixer “Movi-Rod” (Selecta,
Barcelona, Spain) placed in a temperature controlled incubation chamber (Boxcult,
Selecta). A pH-meter model 720 (ThermoOrion, Waltham, USA) was used to adjust the
pHs needed for the experiments.
A peristaltic pump (Gilson, Villiers, France) was used in the SPE experiments in
column mode. In this case, the polymer was packed into 5 mL SPE cartridges.
The elemental analyzer FLASH 1112 from Thermo Finnigan (Waltham, MA, USA) was
used to analyze the content of nitrogen, carbon, oxygen, hydrogen and sulfur in the
polymer. The EVO LS 15 microscope (Zeiss, Oberkochen, Germany) was used to
obtain the micrographs of the MIP and NIP (non imprinted polymer). A labmade
spectrometer (Servicios Generales of the University of Santiago de Compostela) with an
anode of Mo was used for energy dispersive x-ray dispersion fluorescence
measurements.
2.2 Reagents
All the solutions were prepared using ultra-pure water of 18�cm resistance obtained
from a Milli-Q purification device (Millipore Co., Massachusetts, USA).
Methylmercury chloride, MMA, EDMA, phenobarbital and thiourea were supplied by
Sigma (Steinhelm, Germany). The stock standard solution (1000 mg L-1) of Hg(II) was
from Merck (Darmstadt, Germany). AIBN was purchased from Fluka (Steinhelm,
Germany). Tuna fish (BCR-463) certified reference material was obtained from the
Community Bureau of Reference (Brussels, Belgium), and TORT-2 Lobster
hepatopancreas reference material was from the National Research Council of Canada
(NRC, Ottawa, Canada). All the other chemicals (e.g. ammonia for the preparation of
the buffer, hydrochloric acid, acetonitrile, toluene …) were purchased from Panreac and
Scharlau (Barcelona, Spain).
All glass and plastic material was cleaned and kept in 10% (w/w) nitric acid for
at least 48 h. The material was then rinsed three times with ultra-pure water before use.
2.3 Synthesis of the Molecularly Imprinted Polymer
The precipitation method was used for the preparation of approximately 1.5 g of
polymer: 0.075 mmol of MeHgCl and 0.3 mmol of phenobarbital were weighed and
mixed with 0.75 mmol of MAA in a clean glass tube. A volume of 12 mL of the
porogen (acetonitrile:water 4:1) was added and stirred for 5 min with a vortex. The pre-
polymerization mixture was kept in the dark overnight. In case of precipitate formation,
the solution was either filtered or decanted. After placing the tube in an ice bath, 4.5
mmol of the cross-linker EDMA and 0.25 mmol of AIBN (initiator) were added. The
mixture was stirred again for 1 min and purged with argon before closing the tube.
Afterwards, the tube was set in the temperature-controlled incubator chamber on the
low-profile roller at 60 C, and the polymerization was completed after 24 h. The non-
imprinted polymer (NIP) was synthesized following the same procedure but without
adding the methylmercury template. The polymers obtained were filtered, washed with
acetonitrile:water 4:1 and dried at room temperature. The resulting polymers are in a
white powder format and are easily packed in cartridges to work in column mode
instead of batch mode.
2.4 Template removal procedure
Portions of MIP (150 mg) were packed in 5 mL syringes between Teflon frits, and the
template was completely removed after cleaning with 200 mL of an acidic thiourea
solution (1M thiourea in 1M HCl) at a flow rate of 1 mL.min-1. Eluates were analyzed
by HRCSAAS to check the complete removal of the template.
2.5 Solid phase extraction procedure
The reference materials (BCR-463 Tuna fish and TORT-2 Lobster Hepatopancreas)
were analyzed after methylmercury extraction using a modification of the Kwasniak et
al. method [40]. Portions of the materials (200 mg) were weighted and transferred to
glass centrifuge tubes. Each portion was washed with 5 mL of acetone [41], shaking
manually during 15 seconds. Afterwards, a volume of 2.5 mL of 6M HCl was added,
and the mixture was shaken during 1 min. Finally, toluene (2.5 mL) was added to
perform the extraction of methylmercury. The tubes were sonicated for 30 min at 60°C,
and the extracts were centrifuged at 3500 rpm at room temperature for 30 min. The
organic fraction was collected and the extraction was repeated using a fresh portion of
2.5 mL of toluene. The sample was sonicated 15 min and centrifuged again. Organic
fractions were mixed and stored at 4˚C until analysis.
SPE cartridges containing the polymer were conditioned with the NH3/NH4+ buffer
solution at pH 8.0. Toluene extracts or buffered aqueous samples were loaded at a flow
rate of 0.5 mL min-1
. The cartridges were washed with the buffer solution after the
loading step, and elution was performed using 10 mL acidic thiourea solution (1M
thiourea in 1M HCl) at the same flow rate (0.5 mL min-1). Thiourea extracts were
analyzed by HRCSAAS. The procedure used to treat the samples is shown in Fig. 1.
2.6 Determination of Hg(II) and methylmercury by HRCSAAS
The analyses were performed by HRCSAAS after the generation of the vapor using a
flow injection system. Samples were transported by a 3% (v/v) HCl solution (carrier),
and mixed with the reducing solution (0.2% (w/v) NaBH4 stabilized with 0.05% (w/v)
NaOH). The reagents were transferred to the gas-liquid separator through a 500 µL
reaction loop, and an 8-way Gilson peristaltic pump (Gilson, Villiers, France) equipped
with a 3.18 mm i.d. Tygon tube that was used for extracting the waste from the gas-
liquid separator. The Hg vapor was separated from the liquid mixture and was swept to
the quartz cell using a 25 L h-1 Ar flow.
The line used for Hg determination was 253.6492 nm; two hundred pixels were
registered, and three analytical pixels (central pixel ± 1) were used to calculate the peak
volume selected absorbance (A��). Detector integration time was 45s (300 spectra
recordings), and area mode was used. A reference spectrum of 1M thiourea in 1M HCl
was used for background correction, and the instrument selected automatically the
pixels used for correction in each measurement (dynamic background correction). The
operating parameters for HRCSAAS are shown in Table 1.
3. Results and discussions
3.1 Characterization studies
Several techniques were used for the characterization of the molecularly imprinted
polymer (MIP) with and without the methylmercury template, and the non-imprinted
polymer (NIP): elemental analysis, energy dispersive X-ray fluorescence, and scanning
electron microscopy (SEM).
3.1.1 Microanalysis studies
Samples of MIP with methylmercury template, MIP without template and NIP were
analyzed to determine the percentage of nitrogen, carbon, hydrogen, sulfur and oxygen.
Results are shown in Table 2. Both MIP and MIP without template have a higher
percentage of nitrogen due to the trapping of phenobarbital, and an increase in the
amount of sulfur was also observed in the MIP without template. This variation was due
to the presence of the thiourea used for the extraction of the template.
3.1.2 Scanning electron microscopy (SEM)
Digital micrographs of MIP and NIP (Fig.2) were obtained using Scanning Electron
Microscopy (SEM). The pictures were taken after applying the procedure for the
extraction of the template, and aggregates of particles can be observed. There are no
appreciable differences between MIP and NIP in the images.
3.1.3 Energy dispersive X-ray fluorescence
The results obtained using this technique indicate a total elimination of the template
from the MIP after the treatment with 200 mL of acidic thiourea (Fig.3), and the
absence of methylmercury in the polymeric matrix of the NIP.
3.2 Optimization of working conditions
In this study, the use of the MIP developed as a solid phase extraction support in
column mode was possible. Liu et al.[32] used the column mode for the analysis of
methylmercury in human hair samples, but they worked in batch mode to analyze the
compound in soil samples. We used 1M thiourea in 1M HCl because an efficient
solvent is needed for elution of methylmercury or Hg(II). Thus, Singh and Mishra[5]
needed to stir their Hg(II)-TAR imprinted polymer two hours with 1M thiourea in 6M
HCl for extracting Hg(II). A similar procedure was used by Bu�yu �ktiryaki et al. [31] to
extract the methylmercury template with 1M thiourea in 8M HCl.
3.2.1 Influence of pH on MIP retention
The influence of pH on MIP retention was studied after packing 150 mg portions of the
imprinted polymer in 5 mL syringes. A volume of 25 mL of 50 �g/L MeHg+ standards
buffered at pH 6.0, 7.0, 8.0 and 9.0 were loaded at a 0.5 mL.min-1
flow, after the
conditioning of the SPE cartridge at the same pH. Syringes were washed after sample
loading and eluted with 10 mL of acidic thiourea solution. Experiments were performed
in duplicate and the recoveries were calculated. At pH 6.0 the recovery was 82.2%.
Results show that MeHg+ recovery was approximately 100% from pH 7.0 onwards
(106.2 ± 9.7% at pH 7.0; 108.9 ± 1.8 % at pH 8.0; 107.3 ± 0.3 % at pH 9.0). We
selected pH 8.0 to perform all the following experiments because the results were more
reproducible at this pH.
The pH used for extraction is higher than that used by Liu et al. [32] with their
methylmercury imprinted MIP (5.0) using (4-ethenylphenyl)-4-formate-6-phenyl-2,2'-
bipyridine as ligand. It is also slightly higher than the pH corresponding to the
methylmercury imprinted polymer with the ligand MAC (pH 7.0)[31].
3.2.2 Comparison of extraction of Hg(II) and methylmercury
A volume of 25 mL of a 50 �g/L Hg(II) standard buffered at pH 8.0 was loaded at a 0.5
mL.min-1 flow, after the conditioning of the SPE cartridge at the same pH. The
experiment was performed in duplicate, and the acidic extracts were analyzed by
HRCSAAS. The results of the experiments showed that the retention of Hg(II) at pH 8.0
was 83.0 ± 0.7%. Therefore, the imprinted polymer retains both species, mercury and
methylmercury. This is the reason why we extracted the methylmercury from the CRMs
using toluene in the subsequent experiments, and we used the polymer to obtain an
aqueous phase that can be easily introduced in the HRCSAAS system.
3.2.3 Influence of sample loading flow rate
Portions of 0.2 g of the certified reference materials TORT-2 and BCR-483 were treated
following a procedure (section 2.5) based on that proposed by Kwasniak et al.[40] In
these first experiments, toluene and hydrochloric acid were added at the same time.
Toluene extracts were loaded in duplicate at different flows (0.5, 1.0, 2.5 and 5.0 mL
min-1
). The recoveries obtained for the analysis of BCR-463 were approximately 50% in
all cases. As can be observed in Fig.4, the maximum recovery was obtained at 0.5 mL
min-1 for TORT-2; therefore, this was the selected flow for loading the sample.
3.2.4 Influence of elution flow rate
Afterwards, the influence of the elution flow rate (0.5, 1.0, 2.5 and 5.0 mL min-1) with
acidic thiourea (1M thiourea in 1M HCl) was evaluated. The experiments were
performed in duplicate, and the maximum recovery for both certified reference
materials (BCR-483 and TORT-2) was obtained with an elution flow rate of 1.0 mL
min-1 (Fig.5).
In the first experiments (sections 3.2.3 and 3.2.4) toluene and hydrochloric acid
were added at the same time and stirred simultaneously with the sample. This procedure
seems not to be efficient to perform the extraction of methylmercury from BCR-463,
taking into account that the concentration of methylmercury in BCR-463 is
approximately 20 times higher than in TORT-2.
3.2.5 Centrifugation time
Finally, we studied the influence of centrifugation time to separate the toluene extracts.
In these extractions, hydrochloric acid was added to the certified reference materials
previously to the addition of toluene. A volume of 2.5 mL of 6M HCl was added to each
sample, shaking during 1 min, and finally toluene (2.5 mL) was used to perform the
extraction. Experiments were performed in duplicate using centrifugation times of 10,
20 and 30 min, and results showed that recoveries increased till 100% using
centrifugation times of 30 minutes (Fig.6).
3.3 Analytical Performance
The software used for the control of the HRCSAAS spectrometer allows the selection of
the optimum number of pixels for providing the highest sensitivity and reproducibility.
All the measurements during the optimization of the method were performed using 3
analytical pixels (central pixel ± 1), as recommended by the Analytik Jena manufacturer.
3.3.1 Calibration graphs
Calibration graphs were prepared with concentrations of 0, 2.5, 5.0, 7.5 and 10.0 µg L-1
of methylmercury in 1.0 M thiourea/1M HCl, and 3% (v/v) HCl (the carrier for the flow
injection method of analysis) . The following equation was obtained when using 3%
(v/v) HCl as solvent to prepare the standards: A = 0.0547 [Hg(MeHg+)]-0.0118, r =
0.998. In the case of methylmercury in 0.5 M thiourea/1M HCl the equation was: A =
0.0795 [Hg(MeHg+)]-0.0204 , r= 0.997. The slopes of both calibration graphs were
observed to be statistically different. We used the calibration in 1.0 M thiourea/1M HCl
during all the subsequent experiments.
3.3.2 Limit of detection and quantification
The limit of detection (LOD) is defined as the element concentration corresponding to
three times the standard deviation of the measurement of a blank (n =11), and the limit
of quantification (LOQ) is calculated as ten times the standard deviation of the
measurement of a blank. A solution of 3% (v/v) hydrochloric acid was used as a blank.
Limits of detection were calculated using the central pixel (CP), 3 pixels (CP ± 1) and 5
pixels (CP ± 2), and the values obtained are shown in Table 3. The best results were
obtained using the central pixel (LOD = 6.6 �g/Kg, LOQ = 22.0 �g/Kg). The values
obtained are very small in comparison with the limit value established by European
Legislation for mercury in fish (1 mg/Kg) [42]. Moreover, it is assumed that from 60 to
90% of mercury is present in fish as methylmercury [43].
3.3.3 Reproducibility of the method
The relative standard deviation of (RSD(%)) of eleven measurements of a 10 µg L-1
standard was used to estimate the repeatability of the method. Results obtained using 1,
3 or 5 pixels are listed in Table 3. All the values obtained were very similar, ranging
from 6.6 to 6.9%. The polymer was also used repeatedly in at least 5-10 cycles of SPE
without major changes in its performance.
3.3.4 Sorption capacity of the polymer
The sorption capacity of the polymer was studied in toluene and in an aqueous solution
(pH 8.0). Solutions of toluene (5 mL) containing amounts of methylmercury (as
mercury) ranging from 0.25 to 1.5 µg (50-300 µg L-1) were loaded in the cartridges
containing 150 mg of the MIP, and no changes were observed in the loading capacity.
The study was also performed after loading buffer solutions (pH 8.0) with
concentrations of methylmercury ranging from 0.25 to 5 �g (50-1000 µg L-1). A
decrease in the recovery was observed from 3 µg (600 µg L-1) of methylmercury
onwards. Using this value for the calculation, the capacity of the MIP sorbent would
decrease from 20 µg g-1 of polymer onwards.
The loading capacity was also calculated for the non-imprinted polymer (NIP). A
volume of 5 mL of a 500 µg L-1 solution of methylmercury dissolved in toluene (5 µg),
and only 71% of the methylmercury was retained in the NIP, while 100% of the
compound was retained in the MIP. Therefore, there is an imprinting effect added to
other type of interactions that affects the retention of the analyte.
3.3.5 Accuracy
The tuna fish Certified Reference Material BCR-463 and the lobster hepatopancreas
CRM TORT-2 were used to evaluate the accuracy of the SPE method in the
determination of methylmercury. A modification of the method (section 2.5) developed
by Kwaniak et al.[40] was used for the extraction of methylmercury in toluene. The
CRMs were analyzed in triplicate, and results revealed an agreement (t-test, P=0.05)
between the experimental concentrations of methylmercury and the certified values. The
experimental concentration for BCR-463 was 3.14 ± 0.20 µg/g, and the certified value
was 3.04 ± 0.16 µg/g. In the case of TORT-2, the experimental value was 0.155 ± 0.06
µg/g, and the certified value was 0.152 ± 0.013 µg/g of methylmercury (expressed as
mercury).
4. Conclusion
A molecularly imprinted polymer using methylmercury as a template, phenobarbital as
ligand, MMA as monomer and EDMA as cross-linker, was synthesized. The MIP was
characterized by elemental analysis, energy dispersive x-ray fluorescence and scanning
electron microscopy. The polymer presents versatile operating characteristics in
aqueous and organic media (toluene), and works in column mode. The operating
conditions were optimized (centrifugation time, loading and elution flow rates), the
analytical characteristics were studied, and the material was used to analyze
methylmercury in two CRMs of tuna fish and lobster hepatopancreas with good
accuracy.
Acknowledgements
The authors are grateful for the financial support provided by the Xunta de Galicia
(project number: 10PXIB209032PR).
Table 1
Operating parameters for HRCSAAS
Vapor generation system
Step Pump 1 (mL min
-1)
Pump 2 (mL min
-1)
Waste Time Reading
Load 5 6 Sample 10 -
Auto zero 0 6 Sample 10 Yes
Reaction 5 6 Carrier 20 Yes
Washing 0 6 Sample 35 Yes
Spectrophotometer
Current /A 13
Spectral range /pixels 200
Analytical line for Hg/nm 253.6492
Evaluated pixels 1 or 3 (CP ± 1)
Background correction mode With reference
Background correction fit Dynamic
Read time / s 45
Integration mode Area
Number of spectra 300
Temperature of the quartz cell 150
Table 2 Elemental composition of the polymers
Element MIP (with template) MIP (without template) NIP
Carbon 57.19 % 55.26 % 55.74 %
Hydrogen 7.42 % 7.23 % 7.43%
Nitrogen 0.62 % 0.74 % 0.20 %
Sulfur - 2.08 % -
Oxygen 22.2 % 20.92 % 22.58 %
Table 3
Analytical performance
Number of pixels LOD (µg L-1) LOD (µg Kg-1) RSD(%)
CP 0.13 6.61 6.9
CP ± 1 píxel 0.32 16.0 6.8
CP ± 2 píxeles 0.55 27.7 6.6
Figures
Fig.1.Diagram showing the procedure to analyze methymercury
Fig.2. Micrographs of a) MIP without methylmercury template b) NIP
Fig.3. Energy dispersive X-ray fluorescence a) MIP with methylmercury template b)
MIP without template
Fig. 4. Optimization of SPE conditions: Influence of loading flow rate
Fig. 5. Optimization of SPE conditions: Influence of elution flow rate
Fig. 6. Influence of centrifugation time
HIGHLIGHTS
- A simple procedure was used to synthesize an MIP with methylmercury and
phenobarbital
- The polymer was characterized and the conditions for operation were studied
- It was tested with aqueous and organic (toluene) solutions
- Two CRMs of tuna and lobster hepatopancreas were analyzed using the MIP
[1] M. Andac&, S. Mirel, S. S&enel, R. Say, A. Erso'z, A. Denizli, Int. J. Biol. Macrom. 40
(2007) 159-166.�
[2] M. Firouzzare, Q. Wang, Talanta 101 (2012) 261-266.�
[3]�M. Firouzzare, Adv. Mater. Res. 718-720 (2013) 645-649.�
[4] I. Dakova, I. Karadjova, V. Georgieva, G. Georgiev, Talanta 78 (2009) 523-529.�
[5] D.K. Singh, S. Mishra, Desalination 257 (2010) 177-183.�
[6] A. Ray, S.N. Gupta, J. Polym. Sci. A: Polym. Chem. 35 (1997) 3729–3734.�
[7] S. Ashraf, A. Cluley, C. Mercado, A. Mueller, Water Sci. & Technol. 64 (2011)
1325–1332.�
[8] S. Xu, L. Chen, J. Li, Y. Guan, H. Lu, J. Hazard. Mater. 237-238 (2012) 347-54.�
[9] Y. Liu, X. Chang, D. Yang, Y. Guo, S. Meng, Anal. Chim. Acta 538 (2005) 85-91.�
[10] M. Shamsipur, H.R. Rajabi, M.H. Beyzavi, H. Sharghi, Microchim. Acta 180
(2013) 791-799��
[11] X. Tang, D. Niu, C. Bi, B. Shen, Ind. Eng. Chem. Res. 52 (2013) 13120–13127.�
[12] J. Wang, Faming Zhuanli Shenqing (2014) CN 103769059 A 20140507.�
[13] M. Monier, I.M. Kenawy, M.A. Hashem, Carbohydr. Polym. 106 (2014) 49-59.�
[14] M. Monier, D.A. Abdel-Latif, Chem. Eng. J. 221 (2013) 452-460.�
[15] C. Branger, W. Meouche, A. Margaillan, React. Funct. Polym. 73 (2013) 859-875.�
[16] Z. Fan, Talanta 70 (2006) 1164-1169.�
[17] Z. Wang, G. Wu, C. He, Microchim. Acta (2009) 151-157.
[18] B.S. Batlokwa, L. Chimuka, Z. Tshentu, E. Cukrowska, N. Torto, Water SA 38
(2012) 255-260.�
[19] G. Wu, Z. Wang, J. Wang, C. He, Anal. Chim. Acta 582(2007) 304-310..�
[20] D. Zhao, Y. Wang, G. Lin, H. Zhang, G. Li, S. Wang, Guangpu Shiyanshi 30
(2013) 1555-1561. �
[21] I. Dakova, T. Yordanova, I. Karadjova, J. Hazard. Mater. 231–232 (2012) 49-56.�
[22] E. Najafi, F. Aboufazeli, H.R. Lotfi Zadeh Zhad, O. Sadeghi, V. Amani, Food.
Chem. 141 (2013) 4040-4045.�
[23] M.R. Ganjali, T. Alizadeh, F. Azimi, B. Larjani, F. Faridbod, P. Norouzi, Int. J.
Electrochem. Sci. 6 (2011) 5200-5208.�
[24] T. Alizadeh, M.R. Ganjali, M. Zare, Anal. Chim. Acta, 689 (2011) 52-59.�
[25] X.C. Fu, X. Chen, Z. Guo, C.G. Xie, L.T. Kong, J.H. Liu, X.J. Huang, Anal. Chim.
Acta 685 (2011) 21-28.�
[26] X.C. Fu, J. Wu, L. Nie, C.G. Xie, J.H. Liu, X.J. Huang, Anal. Chim. Acta 720
(2012) 29-37.�
[27] H.R. Rajabi, M. Roushani, M. Shmsipur, J. Electroanal. Chem. 693 (2013) 16-22.�
[28] O. Güney, F.Ç. Cebeci, J. Appl. Polym. Sci. 117 (2010) 2373–2379.�
[29] X. Hu, Imprinted photonic polymers and methods for their preparation and use.
PCT Int. Appl. (2013) WO 2013063772 A1 20130510.�
[30] X. Hu, W. Hong, B. Zhao, Method for preparing photonic crystal thin film based
on ion imprinted technology, Faming Zhuanli Shenqing (2014) CN 103804600 A
20140521.�
[31] S. Bu'yu 'ktiryaki, R. Say, A. Denizli, A. Erso'z, Talanta 71 (2007) 699-705.�
[32] Y. Liu, Y. Zai, X. Chang, Y. Guo, S. Meng, F. Feng, Anal. Chim. Acta 575 (2006)
159-165.�
[33] D.P. Krabbenhoft, E.M. Sunderland, Science, 341 (2013) 1457-1458.�
[34] EFSA Panel on Contaminants in the Food Chain (CONTAM), Scientific Opinion
on the risk for public health related to the presence of mercury and methylmercury in
food. EFSA Journal 2012; 10 (12):2985 (241 pages).
http://www.efsa.europa.eu/en/efsajournal/doc/2985.pdf Last visited: 08/06/15.�
[35] EFSA Dietetic Products, Nutrition, and Allergies (NDA), Scientific Opinion on
health benefits of seafood (fish and shellfish) consumption in relation to health risks
associated with exposure to methylmercury, EFSA Journal 2014;12(7):3761 (80 pages).
http://www.efsa.europa.eu/en/efsajournal/doc/3761.pdf Last visited: 08/06/15.
[36] A. S. Curry, Br. Med. J. 1 (1964) 354-355. �
[37] F. Pehr, Clin. Chem. 21 (1975) 1609-1611. �
[38] E. Z. Helman, Clin. Chem.16 (1970) 797-798. �
[39] S.G. Hu, S.W. Wang, S.W. He, Analyst 128 (2003) 1485-1489.�
[40] J. Kwa�niak, L. Falkowska, M. Kwa�niak, Food Chem. 132 (2012) 752-758.�
[41] AOAC. Metals and other elements. Chapter 9 of Official Methods of Analysis
(2005), p. 40�
[42] COMMISSION REGULATION (EC) No 629/2008 of 2 July 2008 amending
Regulation (EC) No 1881/2006 setting maximum levels for certain contaminants in
foodstuffs, Journal of the European Union L 173/6-9.
[43] United Nations Environment Programme. Global mercury assessment, December
2002. http://www.unep.org/gc/gc22/Document/UNEP-GC22-INF3.pdf Last visited:
08/06/15.�
MIP
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organic samples
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