Efficient solid phase extraction of codeine from human urine samples using a novel magnetic molecularly imprinted nanoadsorbent and its spectrofluorometric determination

Article abstract of DOI:10.1039/c5nj01588j

From a medical or clinical point of view, to assess toxicity, adverse effects, interactions and therapeutic efficiency, monitoring drug levels in body fluids, such as urine and plasma, has become increasingly necessary. This study reports on a novel method for determination of trace concentration levels of codeine phosphate in human urine samples. In this regard, a solid phase extraction step, based on a novel magnetic molecularly imprinted polymer nanoadsorbent, has been developed to be used prior to spectrofluorometric analysis of the drug. After optimization of various factors, such as pH, contact time, adsorbent dosage and desorbing solvent, the results showed that using the proposed method sensitive and accurate determination of the drug in the concentration range of 2.0-500.0 ng mL^-1 with the detection limit of 0.67 ng mL^-1 is achievable. The urine sample analysis results show that a powerful method for codeine phosphate determination has been proposed.

Full text of DOI:10.1039/c5nj01588j

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DOI: 10.1039/C5NJ01588J
New Journal of Chemistry
ARTICLE
Efficient solid phase extraction of codeine from human urine
samples using a novel magnetic molecularly imprinted
nanoadsorbent and its spectrofluorometric determination
Received 00th January 20xx,
Accepted 00th January 20xx
Tayyebeh Madrakian*, Fariba Fazl, Mazaher Ahmadi and Abbas Afkhami
DOI: 10.1039/x0xx00000x
www.rsc.org/
From a medical or clinical point of view, in order to assess toxicity, adverse effects, interactions and therapeutic efficiency,
monitoring drugs levels in body fluids such as urine and plasma has become increasingly necessary. This paper, reports on
a novel method for determination of trace concentration levels of codeine phosphate in human urine samples. In this
regard, a solid phase extraction step, based on a novel magnetic molecularly imprinted polymer nanoadsorbent, has been
developed prior to spectrofluorometric analysis of the drug. After optimization of various factors, such as pH, contact time,
adsorbent dosage and desorbing solvent, the results showed that using the proposed method sensitive and accurate
determination of the drug in the concentration range of 2.0-500.0 ng mL-1 with the detection limit of 0.67 ng mL-1 is
achievable. The urine samples analyses results showed that a powerful method for codeine phosphate determination has
been proposed.
extraction and solid phase extraction) for enhancements some
analytical parameters such as detection limit (sensitivity) and
selectivity.
Todays, solid-phase extraction (SPE) is widely used for the
extraction and preconcentration of analytes in various
environmental, food and biological samples. It is the most
popular clean-up technique due to factors such as
Introduction
Codeine (methyl morphine) is one of the most important
constituents of opium and can be prepared by prepared from
morphine by methylation. Its phosphate form (COP) is usually
used for the treatment of gently or moderate pain in clinic
medication. Compared with morphine, the antitussive effect of
codeine is approximately one-third of morphine, and its
convenience, cost, time saving and simplicity, and it is the
most accepted sample pretreatment method todays.2
0-25
At
1
analgesic action is only one-twentieth of morphine’s activity.
present, there are several types of sorbents for SPE, including
normal-phase, reversed-phase, ionic, and other special
sorbents. However, due to their unsatisfactory selectivity,
these traditional sorbents usually cannot efficiently separate
analytes in complex biological or environmental samples.26
A relatively new development in the area of SPE is the use
of molecularly imprinted polymers (MIPs) for the sample
clean-up and development of selective and sensitive analytical
It is stronger than general antipyretic analgesics, and its
function duration is similar to morphine. These properties lead
to a wide prescription of codeine in cough syrups and tablets.
It has moderate analgesic and weak cough suppressant effects.
The analgesic effects are observed because only trace amounts
2
of morphine are formed after the administration of codeine.
However, long-term use of codeine is addictive and excessive
3
, 4
intake even cause death.
Therefore, it is very necessary to
2
6-28
methods.
MIPs are synthetic polymers possessing specific
analysis its content in urine or biological fluids.
cavities designed for a target molecule and are synthesized by
the polymerization of different components. With the
development of molecularly imprinted adsorbents, some
disadvantages of MIPs have emerged and greatly restricted its
application. It was excited for scientists to find that giving MIP
magnetism was an effective approach to overcome the
Various approaches such as gas chromatography tandem
5
-7
mass spectrometry (GC-MS)
chromatography (HPLC) with ultraviolet detection
coupled with tandem mass spectrometric detection (HPLC-MS)
, high performance liquid
8
, 9
and
1
0
11, 12
13, 14
,
chemiluminescent
, capillary electrophoresis
, thin-
layer chromatography (TLC) 5, fluorescence (FL)
1
16, 17
,
2
6, 29, 30
disadvantages of MIPs.
When used as a SPE sorbent,
electrochemistry 1 and chemometrics methods 19 have been
reported for COP determination. Most of these methods
always need a pretreatment step (such as liquid-liquid
, 18
magnetic MIP bead can be dispersed into solution directly and
separated via an external magnetic field, avoiding the
operation of making packed columns as the traditional SPE
adsorbents. Accordingly, an interest has been raised in
preparation and application of magnetic MIPs in recent
Faculty of Chemistry, Bu-Ali Sina University, Hamedan, Iran
2
6, 31-36
years.
These studies greatly extended the preparation
*
Corresponding author. Tel. / Fax: +98-811-8257407
E-mail: madrakian@basu.ac.ir, madrakian@gmail.com (T. Madrakian)
method of magnetic MIPs and made them more efficient as
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ARTICLE
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SPE adsorbents. However, structure of the magnetic supporter 38066 Riva, d/G. via M. Misone, 11/D (TN) ItalyV)ieawtAraticmlebOinelinnet
core), rather than a single Fe
particle as reported in the temperature. A Metrohm model 713 pHD-OmI:e1t0e.1r0w39a/Cs5uNsJe0d158fo8Jr
previous studies, should be better designed to improve the the pH adjustments. A 40 kHz universal ultrasonic cleaner
magnetic performance and enhance the stability of MIPs. water bath (RoHS, Korea) was used. A Knauer 1050 HPLC pump
(
3 4
O
At this wok, a highly selective magnetic COP-imprinted and a Knauer 2850 PDA detector with Macherey nagel column
polymer nanoadsorbent has been synthesized using magnetite C18 (150 mm × 2.5 mm, particle size 4 µm) was used. For the
nanospheres (MNSs) as the magnetic core, a synthesized instrumental control, data collection and processing,
aminoimide monomer (AI) as the functional monomer, chromgate software was employed. A Perkin Elmer (LS50B)
ethylene glycol dimethacrylate (EGDMA) as the cross-linker, luminescence spectrometer was used for the determination of
ammonium persulfate as the initiator, and COP as the COP at λem= 348 nm (λex= 214 nm).
template. The prepared nanoadsorbent has been fully Chemicals
characterized and its affinity to the COP was experimentally
Alborz Bulk Pharmaceutical Company (Kaveh Industrial
evaluated. After optimization of various affecting factors (such
zone, Saveh, Iran) provided COP. Standard solution of 200 mg
as pH, adsorbent dosage and contact time), the adsorbent was
-
1
L
COP was prepared with doubly distilled water (DDW) and
successfully used for extraction of COP from infected human
urine samples.
°
stored at 4 C darkly and working standard solutions of
different COP concentrations were prepared daily by diluting
the stock solution with DDW water. Ethylene glycol (EG) and
-1
polyethylene glycol (PEG, fw~8000 g mol ) were purchased
Experimental
Apparatus
from Sigma-Aldrich (St. Louis, MO, USA). The AI functional
monomer was synthesized according to our recently reported
procedure. All of the other chemicals were purchased from
Merck Company (Merck, Darmstadt, Germany). DDW water
was used throughout this work. Britton-Robinson universal pH
buffer was used for pH adjustment of the working solutions. It
Infrared spectra’s of the polymeric adsorbent were
collected using a FT-IR spectrometer (Perkin-Elmer model
-1
Spectrum GX) with the spectral range of 4000-400 cm . A
transmission electronic microscope (TEM, Philips-CM10)
obtained the nanographs of the adsorbent with measurements
operating at 100 KV. The crystal structure of the synthesized
materials was determined by an X-ray diffractometer (XRD,
was consists of a mixture of 0.04 M H
.04 M CH COOH that was titrated to the desired pH with
NaOH and/or HCl solutions.
3 3 3 4
BO , 0.04 M H PO and
0
3
Scheme 1 Reactions involved in the synthesis of (a) the aminoimide monomer, (b) MNSs and COPMNSs adsorbents
2
| J. Name., 2012, 00, 1-3
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DOI: 10.1039/C5NJ01588J
New Journal of Chemistry
ARTICLE
Synthesis of the aminoimide monomer functional monomer
To a 25.0 mL sample solution containing COP and 10.0 mL
Britton-Robinson buffer solution of pH 6.5, 0.09 g of COPMNSs
was added. The solution was shaken at room temperature for
35.0 min. Subsequently, the COP loaded COPMNSs were
separated from the mixture with a permanent hand-held
magnet within 60 s. The residual amount of the drug in the
solution was determined spectrofluorometrically at λem= 348
nm (λex= 214 nm). The adsorption percentage, i.e., the drug
removal efficiency (%Re), was calculated using the following
equation:
The aminoimide monomer used for preparation of the MIP
layer was synthesized according to our recently reported
procedure with some minor modification (Scheme 1a).
3
4
Briefly, the aminoimide monomer was synthesized by slow
addition of maleic anhydride (1 g) to the solution of
ethylenediamine (1 mL) in DDW (20 mL). The solution was
heated to 120ºC for 1 h, until all the water was removed and
ethylenediamine reacted with maleic anhydride through ring
opening. Then, the unsaturated aminoimide monomer was
prepared by heating the reaction product to 140ºC for 2 h.
Synthesis of the COP imprinted magnetic nanoadsorbent:
(C − C )
0 t
%Re = [
] × 1ꢀꢀ
(1)
C0
Preparation of silica coated magnetite nanospheres (SCMNSs)
where C
o
and C
t
represent the initial and final (after
(Scheme 1b)
-1
adsorption) concentrations of COP in mg L , respectively. Also,
all the experiments were performed at room temperature.
Preconcentration studies for the determination of trace
amounts of COP were performed by adding 110.0 mL of the
FeCl .6H O (1.35 g) was dissolved in ethylene glycol (EG, 40
3
2
mL) to form a clear solution, followed by the addition of
sodium acetate (NaAC, 3.6 g) and polyethylene glycol (PEG, 1.0
g). The mixture was vigorously ultrasonicated for 30.0 min,
then refluxed at 180ºC for 8 h, and finally allowed to cool
down to room temperature. The black products (MNSs) were
-1
solution containing 2.0-500.0 ng mL COP and 60 mL of
Britton-Robinson buffer of pH 6.5 to 0.09 g of COPMNSs; the
solution was stirred for 35.0 min. The concentration of COP
decreased with time due to adsorption by the adsorbent. The
drug loaded nanospheres were separated by magnetic
decantation, and desorption was performed with a 2.0 mL of
methanol. The concentration of COP in the resulting solution
3
7
washed several times with ethanol and dried at 60°C for 6 h.
MNSs were coated with a silica layer to prevent iron oxide
cores from leaching into the mother system under any acidic
circumstances. Briefly, 0.10 g of MNSs nanospheres were
dispersed in the mixture of ethanol (50 mL), DDW water (10
mL), and concentrated ammonia aqueous solution (3 mL),
followed by the addition of tetraethylorthosilicate (TEOS, 2.0
mL). After stirring at room temperature for 1.5 h, the silica
coated MNSs nanospheres (SCMNSs) were separated and
was measured spectrofluorometrically at λem= 348 nm (λex
14 nm).
Adsorption isotherm studies
=
2
An adsorption isotherm describes the fraction of sorbate
molecules that are partitioned between liquid and solid phase
at equilibrium. Adsorption of COP by COPMNSs and NIPMNSs
nanospheres was modeled using Langmuir and Freundlich
adsorption isotherms.
3
8
washed with ethanol and DDW water.
Preparation of COP-imprinted polymer coated SCMNSs
(
(
COPMNSs) and non-imprinted polymer coated SCMNSs
NIPMNSs) (Scheme 1c)
Freundlich isotherm
In order to prepare the COPMNSs, the amidoamine
The Freundlich isotherm is applicable to both monolayers
monomer was polymerized in the presence of SCMNSs (0.5 g),
ammonium persulfate (0.1 g, as the initiator), EGDMA (0.2 mL,
as the cross-linking monomer) and COP (0.01 g, as the
template) in 30 mL DDW at 85ºC for 12 h according to Scheme
(chemisorption) and multilayer adsorption (physisorption) and
is based on the assumption that the adsorbate adsorbs onto
the heterogeneous surface of an adsorbent. The linear form
3
9
of Freundlich equation is expressed as:
1c. The product was separated using a magnet and washed
1
lnq = lnk + lnCꢁ
(2)
with methanol until no template molecule (COP)
spectrofluorometricaly was detected in the washing solution
ꢁ
f
n
F
and then washed overnight with methanol to complete Where K and n are Freundlich isotherm constants related to
remove the template. Finally, the product was dried under adsorption capacity and adsorption intensity, respectively and
vacuum for 12 h. The NIPMNSs were also synthesized by the Ce is the equilibrium concentration (mg L-1).
same procedure, only without the addition of the template.
SPE procedure for COP and its spectrofluorometric
determination
Langmuir isotherm
The Langmuir isotherm assumes monolayer adsorption on
a uniform surface with a finite number of adsorption sites 40
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Once a site is filled, no further sorption can take place at that monomer as the functional monomer, EGDMA aVisewtAhreticlecrOonslinse-
site. As such, the surface will eventually reach a saturation linker, COP as the template and ammonDiuOmI: 1p0e.1r0s3u9l/fCa5tNeJa0s15t8h8eJ
point where the maximum adsorption of the surface will be polymerization reaction initiator.
achieved. The linear form of Langmuir equation may be Characterization of the synthesized adsorbents
written as:
The FT-IR spectra of the products were recorded to verify
(3) the formation of the expected products. The related spectra
C
1
1
ꢁ
=
+
Cꢁ
qꢁ
K q
L
m
qm
are shown in Fig. 1. The characteristic absorption band of Fe-O
-1
in magnetite (around 598 cm ) was observed in Fig. 1a. A
Where q
mg of analyte/ g adsorbent) and K
the strength with which the drug is bound to the adsorbent
m
is the maximum adsorption capacity of the substrate
-1
2
strong peak at 1087 cm in Fig. 1b is attributed to Si-O in SiO .
(
L
is a constant representing
-1
The new absorption peaks at almost 1452 and 1725 cm in Fig.
c are assigned to C-N and C=O bands in the polymer-coated
final product (COPMNSs), respectively. Moreover, new
1
3
-1
(
dm g ).
Urine samples pretreatment
-1
absorption peaks at 2956 and 3000 cm are related to the
Post-dose urine samples were collected from healthy
donors who received one 60 mg of codeine phosphate dose
orally. All urine samples were stored at -20ºC. Then, 110 mL of
each sample was adjusted to pH 6.5 using 0.01-0.1 mol L HCl
and/or NaOH and directly subjected to the SPE procedure. All
experiments were performed in compliance with the relevant
laws and institutional guidelines, and Behbood institute
26
stretching modes of the aliphatic C-H group . Based on the
above results, it can be concluded that the fabrication
procedure has been successfully performed.
-1
The XRD pattern of the COPMNSs in Fig. 2 shows diffraction
peaks that are indexed to (3 1 1), (4 0 0), (5 1 1) and (4 4 0)
reflection characteristics of the cubic spinel phase of
magnetite (JCPDS powder diffraction data file no. 79-0418),
revealing that the resultant nanospheres are mostly
magnetite. The average crystallite size of the COPMNSs
nanospheres was estimated to be 16 nm from the XRD data
(Hamedan, Iran) has approved the experiments. Furthermore,
in order to the method accuracy’s evaluation, the urine
samples were spiked with COP at ng mL concentration levels.
-1
2
3
according to Scherer equation
.
The TEM image of the COPMNSs in Fig. 3b, in comparison
with SCMNSs image (Fig. 3a), indicates that the MNSs
Results and Discussion
In order to synthesize COPMNSs, MNSs were first synthesized nanospheres are enwrapped rather homogeneously in SiO
by a solvothermal reduction method. Then, the synthesized shell, and further by the MIP layer. The average size of the
nanospheres were coated with a layer of SiO
using TEOS synthesized nanospheres was estimated to be about 95 nm.
2
2
silanization agent. Finally, the surface of the synthesized
SCMNSs was imprinted with COP using the amidoamine
Fig. 1 FT-IR spectra of (a) MNSs, (b) SCMNSs and (c) COPMNSs
4
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DOI: 10.1039/C5NJ01588J
New Journal of Chemistry
ARTICLE
2
1
1
1
1
1
00
80
60
40
20
00
surface binding-sites of the adsorbent. The effect of pH on the
COP removal efficiency was investigated in the range 3.0-10.0
(311)
-1
using an initial COP concentration of 2.0 mg L and a stirring
time of 45 min, where the pH was adjusted using Britton-
Robinson buffer. As elucidated in Fig. 5, the maximum value of
COP removal appeared in pH=6.5 and at higher or lower pHs a
significant decrease in COP removal efficiency can be seen.
(440)
(
511)
8
6
4
2
0
0
0
0
0
(400)
4
1
a
Due to the pK value of COP (pKa(COP)= 8.32 ), At pH>8.32, the
predominant form of COP is its neutral form and at the other
range is its protonated form and at the other hand, the
adsorbent surface charge at pH>6.4 is negative and at pH<6.4
is positive. So, electrostatic interactions aren’t responsible for
the related pH effect (Fig. 5). It can be suggested that
hydrophobic interaction and hydrogen bonds between COP
and the MIP cavities (mainly the amine functional group of AI)
is responsible for the high observed removal efficiencies at pH
of 6.5. For further optimizations the pH=6.5 was chosen.
20
30
40
50
60
70
80
2
θ, degree
Fig. 2 XRD pattern for the COPMNSs nanospheres
2
1
0
.5
2
.5
1
.5
0
Fig. 3 TEM image of (a) SCMNSs and (b) COPMNSs nanospheres
2
3
4
5
6
7
8
9
10
11
-
-
-
0.5
-
1
Point of zero charge (pHPZC) of the COPMNSs adsorbent
The pHPZC of the COPMNSs was determined in degassed
1.5
-
2
-
1
0
2
.01 mol L NaNO
3
solution at room temperature. Aliquots of
2.5
0.0 mL 0.01 mol L- NaNO
1
Initial pH
3
were mixed with 0.03 g of the
nanoparticles in several beakers. The initial pH of the solutions
Fig. 4 Point of zero charge of the COPMNSs adsorbent
was adjusted at 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0 and 10.0 using
0
.01-0.1 mol L- of HNO
1
3
and/or NaOH solutions as
1
appropriate. The initial pHs of the solutions were recorded,
and the beakers were covered with parafilm and shaken for 24
h. The final pH values were recorded and the differences
between the initial and final pH (ΔpH) of the solutions were
plotted against their initial pH values. The pHPZC corresponds to
0
0
0
0
.9
.8
.7
.6
0.5
0.4
2
6
the pH where ΔpH=0. The pHPZC for the COPMNSs was
0
0
0
.3
.2
.1
0
determined using the above procedure and was obtained as
6.4. The results are shown at Fig. 4.
Effect of various factors affecting the COP removal efficiency
2
3
4
5
6
7
8
9
10
11
Various factors that could potentially affect the analyte
removal efficiency (i.e. pH, contact time and nanospheres
dosage) were optimized and here are the detailed results:
pH
Fig. 5 Amount of COP uptake per gram of adsorbent at different pH values
Conditions: 0.04 g of COPMNSs, 25 mL of 2.0 mg L of COP, agitation time of 45
-
1
(
min, N=3)
Effect of pH
Solution pH affects the adsorption process of the drug
molecules by affecting both the aqueous chemistry and
Effect of nanospheres dosage
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The dependency of the adsorption of COP on the amount min contact times to evaluate the COP recoveryV.ieTwhAerticrleesOunllitnse
of modified nanospheres was studied at room temperature (Fig. 6) showed that methanol is the mosDtOeI:ff1e0.c1t0i3v9e/Ca5sNaJ0b1a58c8kJ-
and at pH 6.5 by varying the adsorbent amount from 0.02 to extracting solvent and can be used for the quantitative
.12 g in contact with 25.0 mL solution of 2.0 mg L- of COP recovery of the analyte. Desorption rate was found to be rapid
1
0
with agitation time of 45 min. The results showed that the as almost 98% desorption completed at almost 20.0 min.
removal efficiency of COP increased by increasing amount of Initial sample volume
the COPMNSs due to the availability of higher adsorption sites.
The adsorption reached a maximum with 0.09 g of adsorbent adsorption was studied in the range 10.0-200.0 mL; 10.0 mL
The effect of initial sample volume on the analyte
-1
and maximum percentage removal was about 97%.
Effect of contact time
samples containing 2.0 mg L of COP were diluted to 25.0,
0.0, 100.0, 110.0, 150.0 and 200.0 mL with DDW water. Then
5
The effect of contact time on the adsorption of COP was adsorption and desorption processes were performed under
studied to determine the time needed to complete remove of the optimum conditions (pH 6.5; contact time, 35.0 min;
-1
COP by COPMNSs from a 2.0 mg L solution of the analyte at COPMNSs dosage, 0.09 g) as described in the experimental
pH 6.5. A 0.09 g of the adsorbent was added into 25.0 mL of section. The results (results was not shown) showed that the
the COP solution. Fluorescence intensity of COP was analyte contents in the volumes up to 110.0 mL were
monitored versus time to determine variation of the analyte completely and quantitatively adsorbed by the nanospheres,
concentration. It was observed that after a contact time of but there was a decrease in the amount adsorbed at higher
about 35 min, almost all the COP was adsorbed (%Re
>98) and volumes. Therefore, for the determination of trace quantities
this time was much enough to reach semi-equilibrium of the analyte, a sample volume of 110.0 mL was selected in
condition.
order to having highest preconcentration factor.
Effect of various factors affecting the COP preconcentration
efficiency
Adsorption isotherms
For measuring the adsorption capacity of COPMNSs and
The aim of this step is providing the highest NIPMNSs, the absorbents was added into COP solutions at
preconcentration factor and concentration of the adsorbed various concentrations (under optimum condition), and the
analyte into minimum possible volume of desorbing solvent. In suspensions were stirred at room temperature, followed by
this regard, various factor that can potentially affect the COP’S magnetic removal of the absorbent. Adsorption of the COP by
desorbing efficiency (i.e. type and volume of desorbing COPMNSs and NIPMNSs adsorbents were modelled using
solvent, desorbing time and initial sample volume) have been Freundlich and Langmuir adsorption isotherm models. The
optimized. The detailed results are given in bellow:
remained analyte in the supernatants was measured
spectrofluorometrically, and the results were used to plot the
isothermal adsorption curves as shown in Fig. 7. The
equilibrium adsorption data were fitted to Langmuir and
Freundlich isotherm models by linear regression. The resulting
parameters are summarized in Table 1.
1
1
1
4
2
0
8
6
4
2
0
Fig.6 Effect of various eluents on COP recovery
0
10
20
30
40
50
60
70
80
Ce, mg L-1
Desorbing solvent
For desorption studies, COP loaded COPMNSs were first
Fig. 7 Isothermal adsorption curves of COP on (
▲
) COPMNSs and (
■
) NIPMNSs
washed by DDW to remove the unadsorbed COP that loosely adsorbents
attached to the vial and adsorbent. In order to estimate the
recovery of COP from COPMNSs, desorption experiments with
The higher correlation coefficient obtained for the
different reagents (methanol (MeOH), 0.01 mol L NaOH, 0.01 Langmuir model (> 0.99) indicates that the experimental data
mol L HCl, mixture of methanol: 0.01 mol L HCl (1:1 v/v) and are better fitted into this model, and the adsorption of COP
mixture of methanol: 0.01 mol L NaOH (1:1 v/v)) were onto COPMNSs adsorbents is more compatible with Langmuir
performed. After adsorption of COP, the adsorbent was assumptions, i.e., adsorption takes place at specific
magnetically separated and washed with DDW. Then 2.0 mL of homogeneous sites within the adsorbent. According to the
the eluent was added to the COP loaded COPMNSs. Samples results (Table 1), the maximum amount of COP that can be
were collected after 5.0, 10.0, 15.0, 20.0, 25.0, 30.0 and 45.0 adsorbed by COPMNSs and NIPMNSs was found to be 13.44
-1
-1
-1
-1
6
| J. Name., 2012, 00, 1-3
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PNl ee aws eJ do ou rnn oa tl ao df j uC sht emm ai rs gt irny s
Journal Name
ARTICLE
and 4.06 mg g-1 at pH 6.5, respectively. The relatively high adsorbent during these thirteen cycles, indicatViniegw AtrthicaletOnthlinee
adsorption capacity of COPMNSs in comparison with NIPMNSs, fabricated COPMNSs is a reusable andDOsI:ta10b.1le039s/oCl5idNJ0p1h5a8s8eJ
shows that the adsorption of COP molecules takes place at a sorbent for the extraction of COP.
large number of specific homogeneous sites within the
adsorbent (specific cavities of the MIP layer), beside of non- Analytical applications
specific interactions which are approximately identical for both
The
calibration
graph
was
constructed
from
the COPMNSs and the NIPMNSs adsorbents.
spectrofluorometric measurements of the desorbed COP after
performing its adsorption/separation under the optimum
Reusability and stability of the adsorbent
The reusability and stability of COPMNSs for the extraction conditions as described above. The calibration graph was
-1
of COP was assessed by performing thirteen consecutive linear in the range 2.0-500.0 ng mL for a sample volume of
separations/desorption cycles under the optimized conditions 110.0 mL. The calibration equation is I = 0.714C + 0.791 with a
Conditions: 0.09 g of COPMNSs, 110.0 mL of 0.2 mg L of COP, determination coefficient of 0.995 (n = 10), where I is the
agitation time of 35 min). Desorption of COP from the fluorescence intensity of the eluate at λem= 348 nm (λex= 214
F
-1
(
F
-1
adsorbent was performed with methanol as described above. nm) and C is the concentration of the analyte in ng mL .
There was no significant change in the performance of the
Table 1 Adsorption isotherm parameters of Langmuir and Freundlich models for the adsorption of the analyte onto COPMNSs and NIPMNSs adsorbents
Isotherm
models
Langmuir
Freundlich
1/n (L g-1)
-1
max (mg g-1)
13.44
4.06
R2
0.997
0.992
(mg1-1/n L1/n g-1)
1.01
R2
0.859
0.952
K
L
(L mg )
2.55
0.75
q
K
f
COPMNSs
NIPMNSs
0.42
0.32
0.08
Table 2 Assay of COP in infected human urine samples
-
1
Found (ng mL-1)
Experiment No.
Spiked value (ng mL )
Recovery percent
HPLC method
1
2
3
-
12.01±0.04*
21.80±0.03
31.43±0.01
-
11.71±0.07
23.41±0.06
32.04±0.02
10.00
20.00
98.1
97.3
*N=3
The limit of detection, defined as LOD =3S
b
/m, where LOD, expensive, low LOD, wide linear range, easy adsorbent
S
b
and m are the limit of detection, standard deviation of the separation and high removal capacity of the adsorbent.
blank and the slope of the calibration graph, respectively, was
found to be 0.67 ng mL of COP . As the analyte in 110.0 mL of
the sample solution was concentrated into 2.0 mL, a maximum
Table 3 Comparison of the proposed method with some previously reported
methods for COP determination
-1
preconcentration factor of 55.0 was achieved in this method. Method
LOD
ng mL )
1.0
3.0
10.0
0.6
Sample
Ref.
-1
(
The relative standard deviations (RSD) for 100.0 and 10.0 ng
HS-SPME a
RPHPLC b
LC–MS
Human hair
Human blood plasma
Human hair
Human urine
Human urine
Human urine
43
42
-1
mL of the analyte were 0.91% and 1.73% (n = 5), respectively.
The analytical applicability of the proposed method was
evaluated by determining the analyte in human urine samples.
The results are given in Table 2. The results of the spiked
samples show good recoveries of the proposed method and
suggest that the method is a good accurate candidate for COP
4
9
4
c
LLME–HPLC
LC-MS/MS
d
45
1.0
0.67
MIP/SPE/FL
a Headspace Solid-Phase Microextraction
This work
determination in the investigated samples. Furthermore, the b Reverse-Phase High-Performance Liquid Chromatography
4
2
c Liquid-Liquid Microextraction followed by High-Performance Liquid
Chromatography
d Liquid Chromatography tandem Mass Spectrometry
results were compared using HPLC method , and are
tabulated in Table 2. The results show that the two methods
are in good agreement and the proposed method can be used
for effective determination of COP in the urine samples.
Table 3 shows a comparison between the results obtained
by the present method with those obtained by some other
Conclusions
methods reported for the determination of COP. This The novel molecularly imprinted nanoadsorbent, used for
comparison shows that the proposed method analytical recognizing of codeine, was prepared using magnetite
performance is comparable with some sensitive instrumental nanospheres as the magnetic core, a synthesized aminoimide
method, such as HPLC, and in some cases, the method is monomer as the functional monomer, ethylene glycol
superior on the analytical figure of merit bases. Other dimethacrylate as the cross-linker, ammonium persulfate as
advantages of the proposed method are simplicity, less the initiator and codeine as the template. The synthesized
core-shell adsorbent has been fully characterized using XRD,
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 7
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PNl ee aws eJ do ou rnn oa tl ao df j uC sht emm ai rs gt irny s
Page 8 of 9
ARTICLE
Journal Name
FTIR and TEM measurements. The recognition properties and 22. T. Madrakian, A. Afkhami, H. Mahmood-KasVhiaewniArtaicnledOnlMine.
Ahmadi, J. Iran. Chem. Soc., 2013, 10, 481D.OI: 10.1039/C5NJ01588J
3. T. Madrakian, A. Afkhami and M. Ahmadi, Chemosphere, 2013,
applications based on the solid-phase extraction of the
synthesized nanoadsorbent were evaluated. The resulting
nanoadsorbent showed a relatively large adsorption capacity
and fast binding kinetics for recognizing the drug, and the
method showed high recovery, good accuracy and
repeatability in determining of the drug in human urine
samples.
2
2
2
2
2
9
0, 542.
4. A. Afkhami, R. Moosavi and T. Madrakian, Talanta, 2010, 82,
85.
5. A. Afkhami, H. Bagheri and T. Madrakian, Desalination, 2011,
81, 151.
7
2
6. T. Madrakian, A. Afkhami, H. Mahmood-Kashani and M.
Ahmadi, Talanta, 2013, 105, 255.
7. B. Sellergren, Molecularly Imprinted Polymers: Man-Made
Mimics of Antibodies and their Application in Analytical
Chemistry, Elsevier Science, 2000.
Acknowledgements
This work was financially supported by the Bu-Ali Sina
University Research Council and the Center of Excellence in
Development of Environmentally Friendly Methods for
Chemical Synthesis (CEDEFMCS), and the authors acknowledge
the support provided for this work.
2
2
3
3
3
3
3
3
3
3
3
8. T. Madrakian, M. Ahmadi, A. Afkhami and M. Soleimani,
Analyst, 2013, 138, 4542.
9. Z. Lin, W. Cheng, Y. Li, Z. Liu, X. Chen and C. Huang, Anal. Chim.
Acta, 2012, 720, 71.
0. X. Mao, H. Sun, X. He, L. Chen and Y. Zhang, Anal. Methods,
2015, 7, 4708.
1. Y. Ji, J. Yin, Z. Xu, C. Zhao, H. Huang, H. Zhang and C. Wang,
Anal. Bioanal. Chem., 2009, 395, 1125.
2. W. Rao, R. Cai, Y. Yin, F. Long and Z. Zhang, Talanta, 2014, 128,
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