A fast and green preconcentration method based on surfactant ion pair-switchable solvent dispersive liquid–liquid microextraction for determination of phenazopyridine in pharmaceutical and biological samples

Article abstract of DOI:10.1007/s13738-018-1378-z

Herein, a novel, fast, green and sensitive surfactant ion pair-switchable solvent dispersive liquid–liquid microextraction (SIP-SS-DLLME) method was developed for the preconcentration of phenazopyridine. Protonated triethylamine bicarbonate is synthesized

Full text of DOI:10.1007/s13738-018-1378-z

Journal of the Iranian Chemical Society
https://doi.org/10.1007/s13738-018-1378-z
ORIGINAL PAPER
A fast and green preconcentration method based on surfactant ion
pair-switchable solvent dispersive liquid–liquid microextraction
for determination of phenazopyridine in pharmaceutical
and biological samples
Yahya Hamid1 · Mohammad Reza Fat’hi1
Received: 2 October 2017 / Accepted: 18 April 2018
© Iranian Chemical Society 2018
Abstract
Herein, a novel, fast, green and sensitive surfactant ion pair-switchable solvent dispersive liquid–liquid microextraction (SIP-
SS-DLLME) method was developed for the preconcentration of phenazopyridine. Protonated triethylamine bicarbonate is
synthesized by the reaction of triethylamine and CO2 in the presence of water. This protonated switchable solvent (soluble
in water) easily converted to triethylamine which is insoluble in water. Aliquat 336 was used as an ion-pair agent in this
method, which results in the increase of the phenazopyridine extraction into the switchable solvent. Variables affecting the
performance of extraction were studied and optimized. The relative standard deviation (RSD) was 3.1% for five repeated
determinations containing 20 µg/L of phenazopyridine. The linear range of the method for microextraction and determina-
tion of phenazopyridine was found to be 5–180 µg/L with a detection limit of 0.88 µg/L. The presented method was applied
successfully for the determination of phenazopyridine in pharmaceutical and biological samples.
Keywords Phenazopyridine · Aliquat 336 · Surfactant ion pair-switchable solvent dispersive liquid–liquid microextraction ·
Pharmaceutical and biological samples
Introduction
have been used for the determination of phenazopyridine
drug in pharmaceutical and biological samples. However,
chromatographic technique suffers some drawbacks such
as complexity of the instrumental and time-consuming pro-
cess, high cost and high consumption of organic solvents
[8]. Therefore, spectrophotometric techniques were con-
sidered. UV–Vis spectrophotometry is an easy, available,
cheap, and very attractive technique for determination of
phenazopyridine, which the United States Pharmacopeia has
recommended [9]. Due to trace amounts of Phenazopyri-
dine in biological samples, and the possibility of interference
caused by sample matrix, a separation step is indispensa-
ble, especially if a spectrometric technique is employed.This
technique can be easily applied after the preconcentration/
extraction step, with new microextraction methods such as,
dispersive liquid–liquid microextraction (DLLME), cold-
induced aggregation microextraction, static liquid-phase
microextraction and cloud point microextraction [10, 11].
Among the above, the DLLME technique has been of great
interest to researchers because of its simplicity, fast opera-
tion and low cost. This procedure is based on the addition
Drugs are biologically active organic compounds with vari-
ous chemical structures. Phenazopyridine hydrochloride
with the structure of azo dye, is widely used as an analge-
sic and for the treatment of urinary tract infections [1]. In
patients with kidney disease, overdose of this drug causes
kidney failure [2]. Although, azo dyes are known to be asso-
ciated with cancer and evidence has been shown in animal
model, till date, human cancer has not been reported in
relation to the use of phenazopyridine [3]. For this reason,
the determination of phenazopyridine is of great interest to
researchers.
Reports have shown that several analytical techniques
such as UV–visible spectrophotometry [4], electrochemi-
cal methods [3, 5] and chromatographic methods [6, 7]
* Mohammad Reza Fat’hi
mr_fathi@scu.ac.ir
1
Department of Chemistry, Faculty of Science, Shahid
Chamran University of Ahvaz, Ahvaz, Iran
Vol.:(0123456789)
1 3

Journal of the Iranian Chemical Society
of a microliter solvent in the presence of a dispersant agent
[12]. The introduction of surfactants/dispersant agents in
the DLLME can reduce consumption of organic solvent,
increase the interaction of analyte-extraction phase and
increase the stability of solvent [11, 13].
literature, there is no paper on the application of surfactant
ion pair-switchable solvent dispersive liquid–liquid micro-
extraction (SIP-A-SS-DLLME) in phenazopyridine analysis
by UV–Vis spectrophotometry. Following this technique,
Aliquat 336 (as surfactant ion pair) was dispersed in aque-
ous solution containing the sample and switchable solvent
(protonated triethylamine bicarbonate) with the assistance of
a vortex mixer. Then, protonated triethylamine bicarbonate
was easily changed into triethylamine (insoluble in water)
by adding NaOH.
Recently, there has been a great interest in the use of
green solvents in extraction technique. Many green solvents
are found to be properly used as extraction phase because
they frequently exhibit remarkably improved properties
when compared with the conventional organic solvents [11].
The intriguing properties of green solvents, including good
extraction efficiency for pesticides, drug and heavy metal
ions, excellent chemical and thermal stability, adjustable
viscosity and eco-friendly, have expanded its applications
as an extraction phase for DLLME [14, 15].
In this paper, a study on the coapplication of ionic sur-
factant and switchable solvent in the present vortex agent
was presented and their capabilities in the preconcentration
of phenazopyridine was explored. It is shown that the sen-
sitivity increased due to the combination of ionic surfactant
and switchable solvent. The linear range, limit of detection
and relative standard deviation (RSD) were investigated. The
study results showed that the presented method could be
used to determine phenazopyridine in pharmaceutical and
biological samples.
Switchable solvent (SS), a kind of green and smart sol-
vent, is used in catalytic processes, purification, extraction
and separation of chemicals [16]. The feature of this sol-
vent is based on the polarity conversion behavior by car-
bon dioxide. CO2 reacts with water–amine mixture (e.g.,
water–triethylamine) to form an ammonium carbonate (e.g.,
protonated triethylamine bicarbonate), which is soluble in
water [17]. Furthermore, it is cheap, readily available, safe
and quickly removed by purging with inert gas or addition of
NaOH. The most important properties of switchable solvent
include simple and rapid separation, safe and eco-friendly
[18]. During the last few years, there was an increased inter-
est in switchable solvents such as extraction reagent in the
analytical separation for the preconcentration and extraction
of metal complexes and pesticides [18–20].
Experimental
Instruments
Cintra 101 UV–Vis spectrophotometer with glass cell
was used for absorbance measurements (GBC Scientific
Equipment, Australia). Attenuated total reflection Fourier
transform infrared (ATR-FTIR) spectra were recorded on a
Thermo Nicolet IR 100 spectrometer with a diamond ATR
crystal, (USA), (Germany). A Benchtop pH/mV Meter-
860,031 pH meter (India) was utilized for pH measurements.
Despite the considerable features of this solvent, no stud-
ies have been conducted on extraction in the presence of
cationic surfactant. Due to the widespread use of this new
and green solvent in the microextraction of various analytes,
Aliquat 336 is considered as a carrier agent [21]. Aliquat 336
as an ionic surfactant, has been used extensively as phase
transfer catalyst [22] and extraction phase of separation [23]
and modifier of adsorbents [21]. As an ion-pair or carrier
agent in DLLME, it has been proven to possess great ability
for the separation/preconcentration of many kinds of heavy
metals and organic pollutants.[24, 25] The combination of
Aliquat 336 ionic liquid and switchable solvent will have the
combined advantages of ionic surfactants and switchable
solvents. Aliquat 336 as an excellent cationic surfactant is
a significant carrier agent in the extraction and preparation
of green sorbents [26]. In the reaction medium, it leads to
stability by decreasing volatility and increasing viscosity and
hydrophobicity.
Materials and chemicals
All materials used in this study are of analytical purity.
Phenazopyridine hydrochloride was obtained from the
Iranian Pharmaceutical Company, Shahredaru (Tehran,
Iran). Triethylamine, NaOH and HCl were purchased from
Merck (Darmstadt, Germany). Tricaprylylmethylammonium
chloride (Aliquat 336) was purchased from Sigma-Aldrich
Company (Darmstadt, Germany). To prepare Aliquat 336
(3%w/v) solution, 3 g of Aliquat 336 was added to etha-
nol and diluted to mark in a 10 mL volumetric flask. Using
hydrochloric acid and sodium hydroxide solutions, desired
pH was obtained.
Research on the use of switchable solvents as extrac-
tion phase in separation is still few, it will be of great value
to develop the application of switchable solvents so as to
increase the ability of extraction, minimize consumption of
organic solvents and shorten extraction time [27]. From the
The synthesis of hydrophilic form of switchable
solvent
In the preparation of switchable solvent, exposure to a 1:1
mixture of the two immiscible liquids, namely triethylamine
1 3

Journal of the Iranian Chemical Society
(TEA) and water, to gaseous CO2 at ambient temperature
and pressure caused the alteration of the two-phase liquids
mixture, resulting in a single-phase liquid, which is mono-
for 1 min at 2800 rpm. Separation of extraction phase did not
need centrifugation. Finally, a volume of 200 µL of superna-
tant was transferred into a glass cell to measure the increase
in the absorbance at 416 nm against a blank solution which
was prepared with the same extraction technique except that
distilled water was used instead of phenazopyridine.
phasic and soluble in water. About 20 g of dry ice (CO2(s)
)
was gradually added into a beaker containing 200 mL of
ultrapure water and 200 mL trimethylamine (TEA) at room
temperature under magnetic stirring. The solution was
stirred at room temperature for 2 h to ensure that the tri-
ethylamine bicarbonate (p-TEA-CO3, as switchable solvent)
product was obtained.
Results and discussion
SIP‑SS‑DLLME for extraction of phenazopyridine
Real samples preparation
The obtained protonated triethylamine bicarbonate (p-TEA-
CO3) was characterized by ATR-FTIR(to study the func-
tional groups) and used in the following experiments [16]
(shown in Fig. 1). The FTIR spectra of the protonated trieth-
ylammonium carbonate (P-TEA-C) to triethylamine (TEA)
solvents obtained by Attenuated Total Reflection (ATR)-
FT-IR spectroscopy are shown in Fig. 1b. The three bands
achieved at 2967, 2937, and 2873 cm can be attributed to the
stretching vibrations of CH2-symmetric and CH2-asymmet-
ric stretch modes. The absorption band at 3438 cm signifies
the stretching vibration of C–N bond in the FT-IR spectra
of TEA. The FTIR spectra of P-TEA-C show several new
spectral bands, such as those of N–H stretching and bending
vibrations and C–N stretching vibration originally occurring
at 1540, 1451, 1300, 1166, and 894 cm, respectively.
In this study, SIP-SS-DLLME combined with UV–Vis-
ible spectrophotometry was used for the analysis of phena-
zopyridine in pharmaceutical and biological samples. The
interaction mechanism (Fig. 2) of the presented technique
can be expressed by three types of analyte transfer routes
into the switchable solvent during extraction process: (1)
hydrophobic interaction between the hydrophobic nonpolar
regions of phenazopyridine, Aliquat 336 and trimethylamine
(switchable solvent); (2) π-cation interactions between the
aromatic rings of phenazopyridine and the quaternary nitro-
gen of Aliquat 336; (3) hydrogen bonds between the amine
groups of phenazopyridine and the amine group of switch-
able solvent.
Tablet samples were obtained from Shahre Daru Pharmaceu-
tical Company (Tehran, Iran). Five tablets of phenazopyri-
dine were powdered accurately and weighed, and equivalent
of 25 mg was dissolved in water (under ultrasonic radiation
for 5 min) and transferred into a 250 mL calibrated flask and
made up to volume with distilled water. A suitable volume
of this sample solution was diluted further with water so that
the concentration of phenazopyridine in the final solution is
within the linear range.
Urine sample (drug-free) of a healthy volunteer was
placed in a polypropylene centrifuge tube and stored before
analysis in the freezer. The spiked urine sample with phen-
azopyridine was prepared by adding the specified volume
of a standard solution of phenazopyridine to a 10 mL cali-
bration flask and then diluted to the mark with urine. This
urine sample was centrifuged at 5000 rpm for 10 min and in
the following, supernatant was transferred to a clean tube.
Finally, the supernatant was filtered (with 0.45 µm filter)
and diluted with distilled water (to reduce matrix effects).
Drug-free plasma (blank) was provided by the Blood
Transfusion Organization of Khuzestan and stored before
analysis in the freezer. The spiked plasma sample with phen-
azopyridine was prepared by adding the appropriate mixed
standard solution of phenazopyridine with drug-free plasma.
One milliliter of plasma was transferred into a centrifuge
tube containing 0.5 mL zinc sulfate (0.7 M) and 0.1 mL
1 M sodium hydroxide solution. Then, by centrifugation
(5000 rpm at 4 min), the supernatant was separated from
the precipitate protein. The solution obtained was transferred
into a 10 mL calibrated flask and then diluted to mark with
distilled water [28].
When Aliquat 336 (ionic surfactant) was added to the
aqueous solution containing analyte and switchable solvent,
it was suspended on the sample surface due to its immiscibil-
ity with the aqueous solution, which is dispersed by vortex
mixer. Vortex mixer caused the fast creation of tiny droplets
of the Aliquat 336 in the aqueous solution containing sam-
ple and switchable solvent (ionic form), and the collision
surface between ionic liquid, switchable solvent and phena-
zopyridine was enlarged. The presence of Aliquat 336 in the
extraction phase, switchable solvent, has several advantages:
increase the stability of the extraction phase and decrease the
volatility of the switchable solvent. As an extraction phase,
together with the alternating solvent, there is a cooperative
Recommended procedure
An aliquot 400 µL of Aliquat 336 (3%w/v) was transferred
into a 15 mL conical-bottom glass centrifuge tube contain-
ing 10 mL solution of phenazopyridine and 750 µL p-TEA-
CO3 solvent (as switchable solvent) at pH 11, was prepared.
Then, 2 mL of NaOH (10 M) was added to the mixture. The
resulting solution was vigorously shaken with a vortex mixer
1 3

Journal of the Iranian Chemical Society
Fig. 1 ATR-FT-IR spectra of
trimethylamine (TEA) and
protonated triethylammonium
carbonate (p-TEA-CO3)
effect that, with increase in preconcentration, the sensitivity
of the measurement increases.
It was found that the extraction efficiency increased with
increase in the pH of the sample solution up to 9, and the
higher pH had neither enhancement nor negative effect on
the extraction. As phenazopyridine is a weak base, it could
be extracted well at relatively high pH, because the molecule
cannot be protonated under basic conditions (pka of phena-
zopyridine is 5.10). Accordingly, with a decrease in pH of
the sample solution, the electrostatic repulsion between the
Aliquat 336 and the protonated phenazopyridine occurred,
which led to decrease in the extraction efficiency. Therefore,
pH 9 was used for further experiments.
In this work, the adsorption peak of phenazopyridine at
416 nm was obtained and the difference in peak absorption
relative to the blank was used as an analytical signal. The
experimental parameters, including pH value of the solu-
tion, the amount of Aliquat 336 and the volume of extraction
were studied in detail. The effects of optimization param-
eters were evaluated using one variable at a time method.
The optimization of pH value of solution
The pH of the sample solution was introduced as the main
parameter in the extraction phase-analyte interaction. To
determine the most suitable pH of the sample solution,
extraction was evaluated in the pH range of 5–11 (Fig. 3).
Effect of the Aliquat 336
The addition of Aliquat 336 as a cationic surfactant along
with a switchable solvent into the sample solution was the
1 3

Journal of the Iranian Chemical Society
Fig. 2 Schematic of the
surfactant ion pair-switchable
solvent dispersive liquid–liquid
microextraction for determina-
tion for phenazopyridine in
pharmaceutical and biological
samples
Fig. 4 The effect of the extraction phase used for the SIP-SS-DLLME
of phenazopyridine: switchable solvent (750 µL)+Aliquat 336
(400 µL of 3% w/v) and switchable solvent (750 µL)
Fig. 3 The effect of the pH valve of sample solution on absorption
significant benefit of this study: the ions of Aliquat 336
and triethylamine (switchable solvent) are hydrophobic,
which lead to π-cation interaction with phenazopyridine
and enhanced extraction of the switchable solvent. The
effects of Aliquat 336 on the switchable solvent in the
extraction phase were investigated under similar experi-
mental conditions (Fig. 4).
Different volumes of Aliquat 336 (as ionic surfactant)
(3% w/v) in a range of 100–500 µL were used to extract
phenazopyridine from the sample solution. The results
indicated (Fig. 5) that 400 µL of Aliquat 336 (3% w/v)
was enough for the extraction, and further increase in the
volume of Aliquat 336 reduced the extraction percentage
of phenazopyridine, which is probably due to increase in
the dilation of the extracted analyte. Therefore, 400 µL
was selected as the volume of the Aliquat 336.
Fig. 5 The amount of Aliquat 336 (3% w/v) used for the SIP-SS-
DLLME
1 3

Journal of the Iranian Chemical Society
Fig. 6 Effect of volume of ionic-state of switchable solvent in SIP-
SS-DLLME method
Fig. 7 Effect of NaOH (10 M) in SIP-SS-DLLME method
Effect of the extraction volume
Table 1 Analytical figures of merit for the SIP-SS-DLLME method
for determination of phenazopyridine
In this extraction method, 10 M sodium hydroxide was
added to a solution containing the sample, p-TEA-CO3 and
Aliquat 336 as ionic liquid to form the extraction phase.
In this study, 10 mL sample solution of phenazopyridine
was used. The volume of the switchable solvent is a very
important parameter in the microextraction. For this reason,
the effect of the volume of protonated solvent (500, 750 and
1000 µL) was studied. It was found that extraction efficiency
increased with increase in the concentration of solvent (pro-
tonated) up to 750 µL, and decreased when higher volumes
were used (Fig. 6). It should be noted that in the conversion
of the protonated triethylamine bicarbonate (water-soluble)
to triethylamine (water insoluble), the volume of solvent
(non-protonated) obtained as the extraction phase was half
of the volume of solvent (protonated) added to the sample
solution.
Linear range (µg/L)
R2
LOD (µg/L)
RSD (%) (n=3)
Intraday Interday
5–180
0.9981 0.88
2.3
3.9
(y=0.007x+0.0971)
Table 2 Tolerance Limits of
species in presence of 100 µg/L
phenazopyridine
Added species
Na+, K+, Cl−,
Tolerance
limit (mg/L)
1000
SO42−, NO3
Mg2+, Zn2+
Ca2+, Fe2+
Fe3+
−
500
50
25
The volume of NaOH (10 M) (as trigger) in the range of
0.5–2.5 mL was studied. Based on the results, the suitable
volume of NaOH required for phase separation was 2 mL.
Complete reaction of non-ionic solvent formation (TEA) was
attained after adding 2 mL of phenazopyridine drug (Fig. 7).
inter-day precision was investigated through replicate analy-
sis of standard solution of 50 µg/L phenazopyridine on three
successive days. Intra-day and inter-day precisions equal to
2.3 and 3.9%, respectively, were obtained.
Analytical figures of merit
Interference studies
Under optimal conditions, the presented method was inves-
tigated for linearity, limit of detection and relative stand-
ard deviation. The method showed linearity over the cali-
bration range of 5–180 µg/L. Table 1 shows the results of
the statistical analysis of the experimental data. Detection
limit (LOD) for phenazopyridine was calculated as fol-
lows: LOD = 3Sb/m, where Sb is the standard deviation of
intercept and m is the slope. The mean of the absorbance of
five isolate samples solution extract of the studied phena-
zopyridine had a relative standard deviation of 3.1%. The
To achieve the analytical uses of the introduced method,
the effects of some probable species in the actual sample on
the extraction results were investigated. For this purpose,
10 ml containing 100 µg/L of phenazopyridine and the prob-
able species studied with a specific concentration were used.
Extraction of phenazopyridine analyte using the highest con-
centration of possible interferent species with 5% error was
investigated. Results of the effect of probable interferent spe-
cies on extraction of phenazopyridine are shown in Table 2.
1 3

Journal of the Iranian Chemical Society
Table 3 Analysis of the pharmaceutical and biological samples
Table 4 comparison of the presented method(SIP-SS-DLLME) with
the other extraction methods for determination of phenazopyridine
Sample
Tablet
Added (µg/L)
Founded (n=3; µg/L)
Recovery%
Method
HF-LLLME-FIAa 0.5
LODe (µg/L) Linear range (µg/L) References
20
50
–
20.3 0.7
50.9 1.9
N.D*
101.6
101.8
–
5–200
[29]
[30]
[6]
LLE-LC/UVb
10
50–10,000
0.5–1000,1–1000
500–25000
Urine
EME-HPLC-UVc 0.5-1
30
70
–
30
70
30.1 1.2
71.2 2.84
N.D
30.8 1.3
69.2 3.3
100.3
101.7
–
102.8
98.8
CCT-CPEd-spec- 500
trophotometric
[4]
Plasma
SIP-SS-DLLME 0.88
5–180
This method
aHollow fiber-based liquid–liquid–liquid microextraction followed by
flow injection
*Not detected
bLiquid–liquid extraction-liquid chromatography-UV
cElectromembrane extraction-HPLC-UV
dCold column trapping-cloud point extraction
eLimit of detection
Application for the analysis of actual samples
Applicability of this extraction method to actual samples
was evaluated by separation/preconcentration and analysis
of phenazopyridine in the tablet, plasma and urine sam-
ples. The results are given in Table 3. The recoveries are
98.8–102.8% which shows that there is no serious interfer-
ence in the extraction and determination of phenazopyridine
in the tablet, plasma and urine samples.
associated with the rapid accumulation of the extraction
phase. It clearly showed that the presence of Aliquat 336
as an ionic surfactant besides switchable hydrophilic sol-
vent in the extraction phase provides an excellent method to
improve the preconcentration performance. Aliquat 336 as
a cationic surfactant in the switchable solvent medium led
to stability by decreasing volatility and increasing viscosity
and hydrophobicity. The proposed approach had the signifi-
cant advantages of ease of operation using green solvents
without the need for a specific device, enhanced stability
and capability of the extraction phase, and reduced extrac-
tion time compared to any other sensitive methods, such as
cloud point extraction (CPE) and electro-membrane extrac-
tion (EME).
Comparison of the SIP‑SS‑DLLME and other
methods
The extraction and determination methods of phenazopyri-
dine in the actual samples are compared in Table 3. In the
investigation of the methods, the spectrophotometric method
was simple, fast and available as compared to the chroma-
tographic methods that are expensive, complicated and use
organic solvents. The method presented in this study is a
green, simple and fast methodology in which extraction was
done without specific tools and with minimal consumption
of chemicals. This extraction method has good sensitivity to
the determination of phenazopyridine in pharmaceutical and
biological samples (Table 4).
Acknowledgements We appreciate the research council of Shahid
Chamran University for supporting this project.
References
1. M. Taei, F. Hasanpour, M. Movahedi, S. Mohammadian, RSC
Adv. 5, 37431–37439 (2015)
2. F. Hasanpour, M. Taei, M. Movahedi, A. Pazir, J. Mol. Liq. 214,
207–213 (2016)
Conclusions
3. A.A. Ensafi, B. Arashpour, B. Rezaei, A.R. Allafchian, Colloids
Surf B Biointerfaces 111, 270–276 (2013)
A novel green, simple, rapid and sensitive preconcentra-
tion method (SIP-SS-DLLME) was developed based on the
cooperative effect of ionic surfactant and switchable solvent
on the UV–Vis spectrophotometry of phenazopyridine in
pharmaceutical and biological samples. Separation/precon-
centration through the polarity conversion of P-TEA-BC/
TEA solvent was introduced as a safe and green extraction
method without the need for a dispersive solvent or special
equipment. The switchable solvent release in a water-insol-
uble form at the extraction site resulted in the surfactant
dispersion and formation of a cloudy solution in the samples
4. F. Nazari Serenjeh, P. Hashemi, M. Safdarian, Z. Kheirollahi, J.
Iran. Chem. Soc. 11, 733–739 (2014)
5. P.F. Pereira, W.P. da Silva, R.A.A. Muñoz, E.M. Richter, J. Elec-
troanal. Chem. 766, 87–93 (2016)
6. L. Fotouhi, Y. Yamini, R. Hosseini, M. Rezazadeh, Can. J. Chem.
93, 702–707 (2015)
7. Q. Chen, K. Li, Z. Zhang, P. Li, J. Liu, Q. Li, Biopharm Drug
Dispos. 28, 439–444 (2007)
8. A. Larki, M.R. Nasrabadi, N. Pourreza, Propellants Explos. Pyro-
tech. 41, 166–171 (2016)
9. A. Khataee, T.S. Rad, B. Vahid, S. Khorram, Ultrason. Sonochem.
33, 37–46 (2016)
1 3

Journal of the Iranian Chemical Society
10. A.N. Anthemidis, K.-I.G. Ioannou, Talanta 80, 413–421 (2009)
11. B. Peng, Y. Shen, Z. Gao, M. Zhou, Y. Ma, S. Zhao, Food Chem.
176, 288–293 (2015)
21. H. Parham, S. Saeed, J. Chromatogr. A 1336,34–42 (2014)
22. Y. Litaiem, M. Dhahbi, J. Dispers. Sci. Technol. 36, 641–651
(2015)
12. M. Soylak, E. Yilmaz, Desalination 275, 297–301 (2011)
13. Y.E. Unsal, M. Soylak, M. Tuzen, Environ. Monit. Assess. 187,
203 (2015)
23. N. Pourreza, S. Rastegarzadeh, A. Larki, Talanta 134, 24–29
(2015)
24. J. Hassan, N. Zari, K. Tabar-Heydar, S.H. Ahmadi, J. Anal. Sci.
Technol. 7, 22 (2016)
14. M. Akhond, G. Absalan, T. Pourshamsi, A.M. Ramezani, Talanta
154,461–466 (2016)
25. M. Ghobadi, Y. Yamini, B. Ebrahimpour, Ecotoxicol. Environ.
Saf. 112, 68–73 (2015)
15. M. Tuzen, O.Z. Pekiner, Food Chemistry 188, 619–624 (2015)
16. M. Soylak, M. Khan, E. Yilmaz, Anal. Methods 8, 979–986
(2016)
26. W. Wei, D.H.K. Reddy, J.K. Bediako, Y.-S. Yun, Chem. Eng. J.
289, 413–422 (2016)
17. G. Lasarte-Aragonés, R. Lucena, S. Cárdenas, M. Valcárcel, Tal-
anta 131, 645–649 (2015)
27. M.Reclo,E.Yilmaz,M.Soylak,V.AndruchandY.Bazel,Journal of
Molecular Liquids,2017,237,236–241.
18. Naeemullah, F. Shah, T.G. Kazi, H.I. Afridi, A.R. Khan, S.S.
Arain, M.S. Arain, A.H. Panhwar, Anal. Methods 8, 904–911
(2016)
28. N. Lamei, M. Ezoddin, K. Abdi, Talanta 165,176–181 (2017)
29. M. Saraji, A.A.H. Bidgoli, B. Farajmand, J. Sep. Sci. 34, 1708–
1715 (2011)
19. E. Yilmaz, M. Soylak, Anal. Chim. Acta 886, 75–82 (2015)
20. C. Vakh, A. Pochivalov, V. Andruch, L. Moskvin, A. Bulatov,
Anal. Chim. Acta 907, 54–59 (2016)
30. D. Farin, G. Piva, R. Kitzes-Cohen, Chromatographia 52, 179–180
(2000)
1 3