Anal. Methods Environ. Chem. J. 4 (3) (2021) 59-67

Research Article, Issue 3

Analytical Methods in Environmental Chemistry Journal

Journal home page: www.amecj.com/ir

AMECJ

A fast, low-cost and eco-friendly method for routine

determination of Bisphenol-A in landll leachate employing

vortex assisted liquid-liquid extraction

Gustavo Waltzer Fehrenbach

, Daniel Ricardo Arsand

a,*

, Sergiane Caldas Barbosa

, Katia R L Castagno

Pedro Jose Sanches Filho

and Ednei Gilberto Primel

Chemistry Department. Sul-rio-grandense Federal Institute of Education, Science and Technology,

360-96015, Praça 20 de Setembro – 455, Pelotas, RS, Brazil.

School of Chemistry and Food. Federal University of Rio Grande, 900-96203, Av. Itália - Km 8, Rio Grande, RS, Brazil.

ABSTRACT

Landlls are sites designed to receive and nal disposal of a broad

variety of urban solid wastes (USW). The decomposition and

biodegradation processes generate a leachate of high complexity and

toxicity, containing persistent and recalcitrant contaminants that are

not usually monitored. Bisphenol-A (BPA) is a synthetic compound

applied mostly on the production of polycarbonate plastics, epoxy

resins, and is an endocrine disruptor. BPA negatively affects biological

receptors, resulting in harmful effects to nervous and reproductive

system as well metabolic and immune function. The presence of BPA in

USW urges the development of feasible analytical methods to support

the efuent treatment plants and reduce the risks of contamination.

The main goal of this work was to develop an efcient, eco-friendly,

fast and simple method for routine analysis of BPA in the leachate

from landll. A vortex assisted liquid-liquid extraction (VALLME)

using 1-octanol as solvent was performed. BPA recoveries at spiking

levels of 2.5, 6.5 and 12.5 µg L

-1

were between 60 to 104% with

relative standard deviation (RSD) lower than 26%. The linearity

of the method was evaluated and the correlation coefcient was (r)

0.9985. The limit of quantication (LOQ) was 2.5 µg L

-1

with a pre-

concentration factor of 20. The method has advantages such as low

consumption of extraction solvent (150 µL), low cost, easy and fast

determination.

Keywords:

Sanitary landll,

Endocrine disruptors,

VALLME,

Bisphenol-A,

Contaminant

ARTICLE INFO:

Received 5 Jun 2021

Revised form 9 Aug 2021

Accepted 30 Aug 2021

Available online 29 Sep 2021

*Corresponding Author: Daniel Ricardo Arsand

Email: danielarsand@pelotas.ifsul.edu.br

https://doi.org/10.24200/amecj.v4.i03.146

------------------------

1. Introduction

Bisphenol-A (BPA) is a synthetic compound

of wide applicability used in the synthesis of

materials as detergents, polycarbonates, thermal

paper, epoxy resin, and food packaging [1]. It

is classied as endocrine disrupter for having

a structure similar to the steroid hormone

17-β-estradiol, what confers ability to imitate

the estrogen activity [1-3]. BPA effects were

discussed in neurochemistry alterations, prostate

cancer, breast cancer, hormonal alterations,

infertility, and ovaries problems [1, 4, 5]. The

usage of BPA in packs of plastic, thermal papers,

coating of food cans, pharmaceuticals, and

general industry represents a direct source for

human and environment contamination [6,7]. In

countries where the classication and recycling

of urban solid wastes (USW) is not efcient, the

nal disposal of USW occurs mainly in landll

sites. These sites are projected to work in a long

and slowly process of degradation. Although,

degradation processes as photolysis, hydrolysis

and biological still occurs and generates a leachate

of high complexity and toxicity, where the

presence of BPA threatens the environment safety

[8, 9]. A reliable and efcient method is necessary

to evaluate the trace levels of BPA in the complex

matrix of leachate. For that, a pre-concentration

and/or clean-up step have been used to prepare

the sample prior to extraction and analytical

determination of BPA, allowing the quantication

of BPA at trace levels in water and plastic

materials as toys. [10, 11]. In general, the sample

preparation has been performed by methods based

on liquid or solid phase extraction. In the solid

phase extraction (SPE), the analyte is extracted

from the sample by passing the sample through a

column/cartridge packed with polar (e.g. alumina)

or nonpolar sorbent (e.g. C18). Modications as

solid phase microextraction (SPME) have also

been observed for BPA extraction. On the other

hand, liquid-liquid extraction (LLE) methods

are based on the usage of solvents to extract and

separate the analyte from the matrix, usually in

an aqueous and organic phase [7, 11, 13, 14].

SPE and LLE have been used and adapted for

years and their application is well dependent to

the matrix composition, sample properties and

concentration. However, there is a need for non-

tedious and environmentally friendly methods,

employing lower volumes of non-toxic solvents

and signicant recoveries. Vortex-assisted liquid-

liquid microextraction (VALLME) is a technique

based on emulsication procedure where the

extraction applies reduced volumes of a low-

density solvent into water associated with high

energy of vortex mixing [15]. The ne droplets

can rapidly extract target analytes from water due

to shorter diffusion distance and larger interfacial

area. After centrifugation, the oating extractant

phase restores its initial single-drop shape for the

following instrumental analysis. This technique

has showed to be eco-friendly for BPA extraction

in water samples [16]. Gas chromatography (GC)

and high-pressure liquid chromatography (HPLC)

are the main analytical instruments used for BPA

detection. Either are based on the difference of

interaction between the sample in mobile phase

(liquid for HPLC, and gas for GC) and stationary

phase (packed column). Then, the analyte interacts

with the detector that generates an electronic

signal, translated into a peak. Different GC and

HPLC setups have already been described.

The mass spectrometry (MS), ultraviolet (UV)

and uorescence are detectors frequently used

in HPLC, while in GC the MS have been more

applied for the detection of BPA [3, 5, 10-15]. In

this work, the usage of HPLC with diode-array

detector has been chosen due advantages as the

simultaneous acquisition in different wavelengths,

improving the separation of peaks, an important

factor to be considered when working with

complex matrices as leachate [11, 14, 15]. The

challenges of controlling the destiny of USW to

landlls and aware society of a responsible waste

discard is aggravated by the analytical limitations

of detection and quantication methods for BPA in

complex matrices. On this way, a feasible and low-

cost method could collaborate with better health

policies and increase the alert to BPA exposure.

The aim of this study was to develop a fast, robust,

low-cost and accuracy method for routine analysis

of BPA in the complex matrix of landll leachate,

employing VALLME and HPLC-DAD.

2. Material and Methods

2.1. Chemical and samples

The bisphenol A (BPA) standard and analytical

grade acetonitrile (J.T Baker, Mallinckrodt, NJ,

USA) were purchased from Sigma-Aldrich (São

Paulo, Brazil). BPA standard solutions were

prepared in methanol and stored at 4 ºC until use.

Ultrapure water was prepared in a Direct-Q UV3

(Millipore, France), and used as mobile phase as

well as acetonitrile.

The leachate used in this study was collected

according to standard methods (SM:2005) from a

Anal. Methods Environ. Chem. J. 4 (3) (2021) 59-67

landll located in the city of Camaquã, located at the

south of Brazil (30° 49’ 41.9’’S 51° 47’ 39.3’’W).

The samples were stabilized with H

(1 mol

-1

) and kept in the dark at 4 ºC until the analytical

procedures. Then, leachate samples were ltered

out with a Micropore system using cellulose acetate

membranes of 0.45 µm (Sartorius Biolab Products,

Goettingen, Germany), assisted with vacuum from a

vacuum-pump Tecnal TE-0581 (Tecnal, São Paulo,

Brazil), and kept in a pre-washed amber bottle with

acetone aqueous solution 1 mol L

-1

2.2. Apparatus

The BPA determination was carried out in a Waters

high performance liquid chromatography coupled

to a diode array detector 2996 (Waters, Milford,

MA, USA), equipped with a quaternary pump

model 600, Empower PDA software was employed

on the data acquisition. The separation was realised

in a silica-based, reversed-phased analytical

column C18 5 µm ODS2 150 mm x 4.6 (Waters,

Milford, MA, USA). The analytes were eluted with

a mixture of ultrapure 60% H

O and 40% analytical

grade ACN as mobile phase in isocratic mode and

at a ow-rate of 1 mL min

-1

. The injection was made

manually using a syringe with 20 µL of VALLME

extracted sample.

2.3. Vortex-assisted liquid-liquid microextraction

procedure

VALLME extractions were carried out in 10 mL

glass tubes with conical bottom with 10 mL

of ltered leachate and 150 µL of 1-octanol in

quadruplicate (Sigma-Aldrich, São Paulo, Brazil).

The tubes were vortexed (Certomat MV, B. Braun

Biotech International) at 4500 rpm for 5 min,

and centrifuged at 2000 rpm for 5 min (Quimis,

São Paulo, Brazil). The supernatant was taken

out after phase separation with a 250 µL syringe

and transferred to 2 mL tube (Eppendorf 5804

R, Eppendorf, São Paulo, Brazil). The 2 mL tube

was centrifuged once more at 2000 rpm for 2 min

and the supernatant was collected with a syringe,

transferred to a new tube and the volume lled up

to 0.5 mL with methanol. The parameters related

to VALLME and HPLC-DAD were adjusted

before the validation process. The lowest volume

of solvent and sample that resulted in a detectable

and reliable signal of BPA were chosen. Vortex and

centrifugation were based on the visual formation

and stability of the organic layer. Then, a second

centrifugation was realised to remove possible

contaminants carried by the pipetting. Five hundred

microliters of methanol were used to ensure the

complete resuspension of organic phase (Fig.1).

Determination of Bisphenol-A by VALLME Gustavo Waltzer Fehrenbach et al

Fig. 1. Vortex-assisted liquid-liquid microextraction (VALLME) procedure.

2.4. Analytical performance

The proposed method was validated by analysing

parameters as analytical curve, linearity, limit of

detection (LOD), limit of quantication (LOQ),

recovery and precision (intermediate precision and

repeatability), according to Brazilian legislation

(INMETRO - DOQ-CGCRE - 008, 2011) which

stablish the procedures and standards for analytical

determinations. Accuracy was evaluated using

recovery experiments with extraction of 3 different

BPA standard concentrations: 2.5, 6.25 and 12.5

µg L

-1

. The precision in terms of repeatability was

obtained by carrying out the extraction and analysis

of fortied samples. Each spike level was extracted

in three replicates and each extract injected three

times in the HLPC-DAD equipment. Different days

were used for the same spike levels of repeatability

to evaluate the intermediate precision of the

method. Limit of detection (LOD) and the limit of

quantication (LOQ) were obtained using the ratio

signal/noise 3:1 and 10:1, respectively.

3. Results and discussion

3.1. Preliminary analysis

Landll sites receives a broad variety of solid waste

from different sources. The wide application of

BPA and indiscriminate holding of plastic materials

at these sites represents a direct source for BPA

to contaminate soil, water, and environment,

posteriorly reaching human by direct contact or

indirect through contaminated food. Due to the

matrix complexity and low concentrations, a

method to identify and quantify estrogens need to

be specic and selective [17]. A standard solution

of BPA was diluted in methanol (mobile phase) and

added to leachate sample to verify the presence of

interferences in the absorption spectrum of BPA,

required to avoid false positive results. The retention

time for BPA standard in methanol was at 5.8 min

of run and detection wavelength at 227 nm. BPA

fortication was detected in leachate sample at same

retention time as in methanol. The chromatogram

of landll leachate with no fortication is presented

in Figure 2, and it can be observed the absence of

interference at BPA retention time (5.8 min) and

227 nm, conrming the method selectivity.

Anal. Methods Environ. Chem. J. 4 (3) (2021) 59-67

Fig. 2. Chromatogram of landll leachate without BPA fortication.

No interference was detected at retention time for BPA (5.8 min)

3.2. Validation of analytical procedure

The determination of analyte concentration in

different matrices is usually made by a calibration

curve, preparing concentrations of stock

standard solution and relating to absorbance

units obtained for each concentration, generating

an equation used to quantify the analyte in real

samples. Furthermore, this procedure is also

applied to measure the correlation between

2 factors, a necessary factor in the process of

validation. The maximum value for correlation

coefficient (r) is 1, ensuring the relation between

absorbance and concentration. The calibration

curve was prepared with 5 concentrations of

standard BPA in methanol, ranging from 0.05

to 2.5 mg L

-1

(n= 3). The curve showed a high

linear correlation (r) of 0.9985, overcoming

the requirements stablished by the Brazilian

legislation (ANVISA: 0.99 and INMETRO:

0.90) and allowing the use to determine BPA in

leachate sample.

LOD and LOQ represents the limits of detection

and quantication of a method. LOD is dened

as the smaller concentration of analyte that can

be detected without guarantee or reliability. LOQ

is the lowest concentration where the analyte can

be determined with precision. Appling the ratio

signal-noise to obtain the LOD (3:1) and LOQ

(10:1), the values found were 0.8 and 2.5 µg L

-1

respectively. These values are in agreement with

other microextraction techniques proposed for

BPA detection as showed in Table 1. Recoveries

were determined in 2.5, 6.25 and 12.5 µg L

-1

levels

(Fig. 3), obtaining an RSD from 60 to 104% and

RSD from 11 to 26%. Intermediate precision was

determined in different days of analyses and the

recoveries obtained were between 81% and 97%

with RSD lower than 16%.

Determination of Bisphenol-A by VALLME Gustavo Waltzer Fehrenbach et al

Fig. 3. Evaluation of method accuracy, repeatability, and intermediate precision

by recoveries (%) of different BPA fortications (µg L

-1

)

The highest recoveries and consequently accuracy,

repeatability and intermediate precision were

obtained with 12.5 µg L

-1

of BPA. These results can

also be observed in Table 1, where are presented

the corresponding recoveries of 2.5, 6.25, and 12.5

µg L

-1

BPA fortications in landll leachate.

The specicity of the method is also observed in

the chromatograms (Fig. 4) of BPA in methanol

(4a) and landll fortied leachate (4b).

In the Table 2 are presented the results of BPA

determination in diverse matrices less complex than

landll leachate. Therefore, the obtained results

in our research agree with the literature for BPA

extraction from liquid samples: SPE [7] with serial

processes of homogenization-vortex-sonication-

centrifugation-evaporation-resuspension of

sample [18], Micro-QuEChERS-GC/MS [19],

and DLLME [20]. Correia-Sá et al [19] obtained

recoveries of BPA from 70 to 120% and RSD

from 3 to 11% applying Micro-QuEChERS-GC/

MS in human urine, a simpler matrix than landll

leachate. Laganà et al [17] obtained 99-103%

of recovery for BPA fortications in river and

sewage treatment (inuent and efuent) samples.

Anal. Methods Environ. Chem. J. 4 (3) (2021) 59-67

Table 1. Recoveries (%) in landll leachate fortied with 2.5, 6.25, and 12.5 µg L

-1

of BPA stock.

Results are based on the recoveries obtained for the respective stock in methanol.

Stock (µg L

-1

)

Samples (%recovery)

1 2 3 4 5

2.5 69.89 73.87 38.87 75.93 40.28

6.25 103.46 110.89 105.49 95.13 95.73

12.5 97.00 93.24 114.55 117.02 80.66

Fig. 4. Chromatogram of BPA standard solution (a) and fortied sample (b).

The signals were generated with 12.5 µg L

-1

of BPA

As showed in Figure 4, BPA can be determined

in landll leachate with no signicant matrix

interference and reliable results, followed by

easily detection. The method is also eco-friendly,

requiring less than 1 mL of solvent per analysis

and not time demanding.

The protocol in this method is ideal for routine

and quick analysis, versatile and can be used in

a broad spectrum of matrix with high extraction

rates, easy cleanup step, low RSD, feasibility, low

consumption of solvents, and non-expensive.

4. Conclusions

On this article we developed an analytical

procedure for BPA determination in landll

leachate. A low volume of 1-octanol (150 µL) was

used as extraction solvent in the vortex-assisted

liquid-liquid microextraction (VALLME) in a

simple procedure that takes around 20 min to be

executed. The proposed method was validated

by adding standard concentrations of BPA in

leachate and quantifying the recoveries, with

a full analysis of standard deviation, accuracy,

repeatability, intermediate precision, LOD, and

LOQ. BPA recoveries were between 60 to 104%

with relative standard deviation (RSD) lower

than 26%, and linearity of 0.9985. The limit of

quantication (LOQ) was 2.5 µg L

-1

with a pre-

concentration factor of 20. Thereby, the proposed

methodology is eco-friendly, requiring a low

volume of sample and extraction solvent. The

method present technical features that adequate

for BPA routine analysis and also the potential

to be applied in BPA quantication in simpler

matrices.

5. Declaration of interest

The authors declare no conict of interest.

6. Acknowledgements

The authors are grateful to the Brazilian National

Council for Scientic and Technological

Development (CNPq) for providing grants for this

study, to Sul-rio-grandense Federal Institute for

Education, Science and Technology (IFSul) and to

University of Rio Grande (FURG) for its nancial

support.

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Determination of Bisphenol-A by VALLME Gustavo Waltzer Fehrenbach et al

Table 2. Recovery (%), limit of quantication (LOQ), limit of detection (LOD) and relative standard deviation

(RSD%) of BPA determination methods obtained by different authors in diverse matrices and complexities.

Matrix Recoveries (%) LOQ LOD RSD (%) References

Landll leachate 60-104 2.5 µg L

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11-26 **

Urine 0-120 0.43 µg L

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