Journal of Chromatography A, 1216 (2009) 1511–1514
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Journal of Chromatography A
journal homepage: www.elsevier.com/locate/chroma
Dispersive liquid–liquid microextraction combined with high-performance liquid
chromatography-UV detection as a very simple, rapid and sensitive method for
the determination of bisphenol A in water samples
Mohammad Rezaeea, Yadollah Yaminia,∗, Shahab Shariatib, Ali Esrafilia, Mojtaba Shamsipurc
aDepartment of Chemistry, Tarbiat Modares University, P.O. Box 14115-175, Tehran, Iran
bDepartment of Chemistry, Islamic Azad University, Rasht Branch, Rasht, Iran
cDepartment of Chemistry, Faculty of Sciences, Razi University, Kermanshah, Iran
a r t i c l ei n f o
Received 11 November 2008
Received in revised form
23 December 2008
Accepted 31 December 2008
Available online 8 January 2009
Dispersive liquid–liquid microextraction
a b s t r a c t
Dispersive liquid–liquid microextraction (DLLME) coupled with high-performance liquid chromatogra-
phy (HPLC)-UV detection was applied for the extraction and determination of bisphenol A (BPA) in water
samples. An appropriate mixture of acetone (disperser solvent) and chloroform (extraction solvent) was
injected rapidly into a water sample containing BPA. After extraction, sedimented phase was analyzed
by HPLC-UV. Under the optimum conditions (extractant solvent: 142?L of chloroform, disperser sol-
vent: 2.0mL of acetone, and without salt addition), the calibration graph was linear in the range of
0.5–100?gL−1with the detection limit of 0.07?gL−1for BPA. The relative standard deviation (RSD, n=5)
for the extraction and determination of 100?gL−1of BPA in the aqueous samples was 6.0%. The results
of trace amount of BPA in water samples and suitable results were obtained.
© 2009 Elsevier B.V. All rights reserved.
Bisphenol A (BPA) is a chemical used in polycarbonate plastics,
epoxy resins and also in various industrial products. In 1993, Krish-
nan et al. reported that BPA exhibited estrogenic activity and is
released from polycarbonate flasks during autoclaving . In addi-
tion, the estrogenic activity of BPA has been extensively evaluated
by a variety of assays [2–3].
Although many studies have been done for detection of BPA in
environmental samples [4–7], the effect of BPA on environmental
samples still remains a controversial issue. Highly reliable methods
are required for the detection of trace compounds with estro-
extraction (LLE) , solid-phase extraction (SPE) [9–11] and molec-
ularly imprinted solid-phase extraction (MISPE) [12,13] have been
solventless and solvent minimized polymer sorption techniques
such as solid-phase microextraction (SPME)  and stir bar sorp-
tive extraction (SBSE)  have been successfully applied for the
extraction of BPA from water samples. Liquid-phase microextrac-
tion (LPME), that use only a single droplet of a solvent has been
∗Corresponding author. Tel.: +98 21 82883417; fax: +98 21 88006544.
E-mail address: firstname.lastname@example.org (Y. Yamini).
developed for the extraction of different analytes from water sam-
of BPA in water samples .
liquid–liquid microextraction (DLLME) as a powerful percon-
centration technique was demonstrated by Rezaee et al. . The
performance of DLLME was illustrated by extraction of different
organic and inorganic compounds [18–25] from water samples.
In the present study, the applicability of the DLLME combined
with HPLC-UV for the extraction and determination of BPA in water
samples was investigated.
2.1. Chemicals and reagents
Bisphenol A was purchased from Merck (Darmstadt, Germany).
HPLC-grade solvents were used throughout of the experiments and
were obtained from Merck. The ultra-pure water used was purified
on a model Aqua Max-Ultra Youngling Ultra-Pure water purifica-
dissolved in methanol to obtain stock solution of the analyte with
a concentration of 250mgL−1. Working standard solutions were
freshly prepared by diluting the standard solution of the analyte
with ultra-pure water to the required concentration.
0021-9673/$ – see front matter © 2009 Elsevier B.V. All rights reserved.
M. Rezaee et al. / J. Chromatogr. A 1216 (2009) 1511–1514
2.2. HPLC system
equipped with a 9012 HPLC pump (Mulgrave, Australia), a 9010
autosampler (having a 20?L sample loop) and a Varian 9050
UV–vis detector. Separations were carried out on a Zorbax Extend
C18column (15cm×4.6mm, with 3?L particle size) from Agilent
(Wilmington, DE, USA). A mixture of water and acetonitrile (55:44)
at a flow rate of 1mLmin−1was used as a mobile phase in isocratic
elution mode. The injection volume was 20?L for all the solutions
and the detection was performed at the wavelength of 224nm.
2.3. Dispersive liquid–liquid microextraction procedure
A 10.0mL of ultra-pure water was placed in a 40mL glass tube
with conical bottom and spiked at the level of 100?gL−1of BPA.
Acetone (2.0mL), as disperser solvent, (containing 142?L chloro-
form) was injected rapidly into the sample solution using a 5.0mL
gastight Hamilton syringe (Bonaduz, Switzerland). The produced
cloudy solution was centrifuged for 5min at 6000rpm by apply-
ing the model 2010 D Centurion Scientific Centrifuge (West Sussex,
completely transferred into another test tube and after evaporation
of the solvent in a water bath; the residue was dissolved in 30?L
of HPLC-grade methanol and injected into the HPLC. All the experi-
ments were performed in triplicates and means of the results were
calculated and reported.
3. Results and discussion
Preconcentration factor (PF) and percent extraction recovery
(ER%) as analytical responses were calculated based on the follow-
ER% = Csed× Vsed/C0× Vaq× 100
where Csedand C0are concentration of the analyte in the sed-
imented phase and initial concentration of the analyte in the
aqueous sample, respectively. Vsedand Vaqare the volume of the
sedimented phase and volume of the aqueous sample, respectively.
Csedis calculated from a calibration curve which was obtained by
direct injection of BPA with the concentrations in the range of
On the other hand the relative recovery (RR) was obtained from
the following equation:
RR% =Cfound− Creal
addition of known amount of standard in the real sample, the con-
amount of standard which was spiked to the real sample, respec-
3.1. Selection of extractant solvent
In the present study, chlorobenzene (density, 1.11gmL−1), car-
bon tetrachloride (density, 1.59gmL−1) and chloroform (density,
1.48gmL−1) were selected as extractant solvents. The study was
performed by using 2.0mL of acetone containing different vol-
umes of the extractant solvent to produce about 30?L of the
sedimented phase. Thereby, 71, 76 and 142?L of chlorobenzene,
carbon tetrachloride and chloroform were used, respectively. ER%
using chlorobenzene, carbon tetrachloride and chloroform were
33.9%, 28.3% and 45.2%, respectively. The results revealed that chlo-
roform has the highest extraction recovery in comparison with the
other tested solvents. It is probably because of higher solubility of
BPA in chloroform in comparison with chlorobenzene and carbon
tetrachloride. Also, evaporation of chloroform is easier than the
other tested solvents. Therefore, chloroform was selected as the
3.2. Selection of disperser solvent
Acetone, acetonitrile and methanol, which are miscible with
water and the extactant solvents, were selected as disperser
solvents. A series of sample solutions were prepared by the
injection of 2.0mL of each disperser solvent containing 142?L
chloroform (as extractant solvent) into the sample solution. Con-
sidering the sedimented phase volume, it was found that with
ume was very higher than 30?L and the cloudy state was not
formed well, whereas in the case of chloroform–methanol, and
chloroform–acetone, the sedimented volume was about 30?L.
Therefore, acetone and methanol could be selected as disperser
solvents for further studies. Further experiments revealed that the
respectively. According to the results, acetone has the higher per-
cent recovery, lower toxicity and lower cost in comparison with
methanol. Therefore, acetone was selected for further studies.
3.3. Effect of extractant solvent volume
To examine the effect of extractant solvent volume on the ER%,
DLLME procedures. By increasing the volume of chloroform from
122 to 162?L, the volume of the sedimented phase increases from
10 to 56?L. Also, according to Fig. 1, by increasing the volume
of chloroform, the ER% of analyte increases. On the other hand,
ER%. In the following studies, 142?L of chloroform was selected as
an optimal volume of the extractant solvent.
3.4. Effect of disperser solvent volume and extraction time
of sedimented phase. To obtain a constant volume of sedimented
use of different volumes of acetone (0.50, 1.0, 2.0 and 4.0mL) con-
taining 100, 120, 142 and 158?L of chloroform, respectively. The
obtained results showed that ER% of BPA increases by increasing of
the volume of acetone and then decreases by further increasing of
Fig. 1. Effect of the extractant solvent (CHCl3) volume on the PF (?) and ER% (?) of
BPA. Extraction conditions: water sample volume, 10.0mL; disperser solvent (ace-
tone) volume, 2.0mL; concentration of BPA, 100?gL−1.
M. Rezaee et al. / J. Chromatogr. A 1216 (2009) 1511–1514
Determination of BPA in river and tap water samples.
Sample Concentration of BPA (?gL−1) Added BPA (?gL−1) Found BPA (?gL−1) (± RSD%d) (n=3)
Relative recovery (%)
aKolakchal river water (Tehran, Iran).
bThe water was taken from Tarbiat Modares University (Tehran, Iran).
the volume of acetone. It seems that, in the lower volumes of ace-
tone, a cloudy state is not formed well, thereby, the recovery is low.
increases. Therefore, the extraction efficiency decreases due to the
decrease of distribution coefficient. A 2.0mL of acetone was chosen
as optimum volume.
According to the other reports [18–25], time has no influence
on the extraction efficiency, because in DLLME, the surface area
between the extractant solvent and the aqueous phase is infinitely
large. In the present method, centrifuging of the sample solution is
time determining step, which is about 3min.
3.5. Salt addition
The effect of salt addition on the extraction recovery of BPA was
evaluated by adding NaCl (0–8%, w/v) into the aqueous solution
containing 100?gL−1of BPA and applying the DLLME procedure.
By increasing of NaCl%, the volume of sedimented phase increases
(from 30 to 50?L), because of the decrease in solubility of the
extractant solvent in the presence of salt. Fig. 2 shows that PF
decreases in the presence of salt; because of increasing in the vol-
ume of the sedimented phase. No significant effect on ER% was
observed when different amounts of sodium chloride were added
into the sample solution (Fig. 2).
3.6. Quantitative analysis
Calibration curves were obtained under the optimized condi-
tions with linear dynamic range of 0.5–100?gL−1and correlation
of determination (r2) of 0.997. The PF and ER% of the method were
of BPA and the sample volume of 10.0mL. The relative standard
deviation (RSD, n=5) at the concentration level of 100?gL−1was
6.0%. The limit of detection (LOD) based on signal-to-noise ratio
(S/N) of 3 was 0.07?gL−1.
3.7. Real water analysis
River and tap water samples were collected from Kolakchal
River and Tarbiat Modares University (Tehran, Iran), respectively,
Fig. 2. Effect of salt addition on the PF (?) and ER% (?) of BPA. Extraction condi-
tions: water sample volume, 10.0mL; disperser solvent (acetone) volume, 2.0mL;
extractant solvent (CHCl3) volume, 142?L; concentration of BPA, 100?gL−1.
and analyzed by the DLLME combined with HPLC-UV. The results
they were spiked with BPA standards to assess matrix effects. Fig. 3
shows the chromatograms obtained for the river water samples
before and after spiking with two different concentrations of BPA
(1 and 5?gL−1). Also, the results of relative recoveries of the river
and tap water samples are tabulated in Table 1. The data in Table 1
show that the relative recoveries of BPA were in the ranges of
93.4%–98.2%, demonstrating that the river and tap waters matrices
had little effect on the DLLME.
3.8. Comparison of DLLME with LPME, SPME and SBSE
volumes for LPME , SBSE , SPME [27,14] and DLLME method
for the extraction and determination of BPA in water samples. The
with 1?gL−1(B) and 5?gL−1(C) using DLLME method combined with HPLC-UV
under optimum conditions.
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M. Rezaee et al. / J. Chromatogr. A 1216 (2009) 1511–1514
Comparison of DLLME–HPLC-UV with other similar methods.
MethodsLOD (?gL−1)LR (?gL−1) RSD (%)Extraction time (min)Sample volume (mL)Reference
LPME without derivatization-GC–MS
LPME with in situ derivatization-GC–MS
SBSE without derivatization -GC–MS
SBSE with in situ derivatization -GC–MS
10 the present method
results show that the extraction time in DLLME is very short and
less than 3min. While, extraction time for SPME, LPME and SBSE
ranged from 20 to 90min, without equilibrium in most cases. The
RSDs for the DLLME is low and approximately the same as SPME,
LPME and SBSE. DLLME has acceptable LOD (0.07?gL−1) and good
liner range (0.5–100?gL−1) without using derivatization reagents
and applying very sensitive determination methods like GC–MS
and HPLC-MS. It is worthy to note that the derivatization process
needs to spend more time and consume chemical reagent that
complicated the extraction process. The volume of sample solu-
tion required for DLLME is about 10mL, which is similar to that of
the stirring speed has no influence in DLLME efficiency. In addition
to other advantages of DLLME, it is very simple, rapid, inexpensive
and easy to use.
This paper describes the application of the DLLME method com-
bined with HPLC-UV, for determination of trace amounts of BPA
in water samples. The relative recoveries for BPA in the ranges of
ces had little effect on the DLLME.
Comparing to the other methods, in DLLME, consumption of
toxic organic solvents is minimum. Also the proposed method has
lowered LOD and much shorter extraction time.
This work was supported by a grant from the Iran National Sci-
ence Foundation, INSF (grant no. 86023/06).
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