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TRANSCRIPT
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8/13/2019 E01.OR
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ExTech
2013
15thInternational Symposium on Advances in Extraction Technologies
36a
Reunio Anual da Sociedade Brasileira de Qumica
A simple and quick method for determination of pesticides in
environmental water by HF-LPME-GC/MS
Helvcio C. Menezes*; Breno, P. Paulo; Maria J. N. Paiva; Zenilda L. Cardeal
Departamento de Qumica, Universidade Federal de Minas Gerais, UFMG, Belo Horizonte, MG 31270-901, Brazil
*[email protected]:pesticides, HF-LPME, GC/MS
INTRODUCTION
Contamination of surface and ground waters by
pesticides increased dramatically during the past two
decades. In order to control unwanted species of
plants or animals that cause damage or interferewith the production or storage several pesticides, are
used. Pesticides and their degradation products may
spread through the environment and frequently
contaminate surface and ground waters1. The
determination of pesticides in environmental
samples is of great interest due to their toxicity,
carcinogenicity, or endocrine disrupting effects2.
Since the pesticides are present at trace level and
wide distribution in complex water environment, it isrequired to develop efficient sample extraction and
preconcentration methods for their determination.
Liquidliquid extraction (LLE), solid-phase extraction
(SPE), solid-phase microextraction (SPME), single-
drop microextraction (SDME), and hollow fibre liquid-
phase microextraction (HF-LPME) are the methods
that have been commonly used for the sample
preparation of pesticides and related compounds in
water samples3
.
HF-LPME is an attractive sample preparation that
use a single hollow fibre connected with a syringe
needle4. This method presents high preconcentration
factors using really small amounts of extraction
solvent. This study proposes a simple and quick
sampling of eleven pesticides in environmental water
matrix using gas chomatography coupled to mass
spectrometry (GC/MS).
EXPERIMENTAL
The pesticides studied in this work are the following:
Parathion-methyl, Chlorpyriphos, Captan,
Procymidone, Endosulfan, Protiophos, Cipronazole,
Etion, Triazophos, Phosmet, and Mirex.
The extractions were performed with propylene fibre
of 6 cm length, internal diameter of 600 m and a
wall thickness of 200 m. Before extraction the
hollow fibre was filled with 30 L of solvent using a
microsyringe. Then, the solvent-filled fibre was
immersed into the vial containing 15 mL of aqueous
pesticides solutions for extraction under magnetic
stirring.
RESULTS AND DISCUSSION
The acceptor phases 1-octanol, ethyl decanoate,
and ethyl octanoate were tested for extraction of
pesticides by HF-LPME, and ethyl octanoate showed
highest ability of extraction.
Different agitation speeds were tested using ethyl
octanoate as acceptor phase. The speed chosen as
the most suitable for extraction was 200 rpm.
Figure 1 shows the study of pesticides efficiency
extraction using HF-LPME with ethyl octanoate at
200 rpm with different exposure times. The results
shows that after 30 minutes there is no significant
increase in extraction estimated by the peak area.
The Figure 2 shows the chromatogram obtained
after extraction of selected pesticides under the
optimized conditions of extraction.
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ExTech
2013
15thInternational Symposium on Advances in Extraction Technologies
25aReunio Anual da Sociedade Brasileira de Qumica - SBQ 2
Figure 1.Effect ofexposure times on the extractionefficiency of pesticides from the aqueous donor
phase usingHF-LPME-GC/MS.
Figure 2. Chromatogram of pesticides GC/MS
analysis using HF-LPME extraction for 30 minutes in
aqueous donor solution spiked at 50 g L1
, and
ethyl octanoate as acceptor phase. 1, Parathion-
methyl; 2, Chlorpyriphos; 3, Captan; 4, Procymidone;
5, Endosulfan; 6, Protiophos; 7, Cipronazole; 8,Etion; 9, Triazophos; 10, Phosmet; 11, Mirex.
Table 1 shows the merit parametersof the optimized
two-phase HF-LPME procedure for determination of
selected pesticides in water.
Table 1. Performance characteristics of the
optimised two-phase HF-LPME-GC/MS procedure
for determination of selected pesticides in water.
The method HF-LPME-GC/MS was applied to the
analysis of three real samples of surface water
collected in a rural area of Minas Gerais, Brazil. Only
one sample showed a concentration of Parathion-
methyl of 0.15 g L1
. Cipronazole and Triazophos
were also detected in this sample.
CONCLUSION
The two-phase HF-LPME-GC/MS method wasdeveloped, optimized and applied to the analysis of
eleven pesticides in environmental water samples.
This procedure is selective, simple, quick, and no
require pretreatment of the sample. In addition the
proposed method showed good linearity, low
detection and quantification limits, high selectivity
and good repeatability for the pesticides selected.
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3.M.I. Pinto, Gerhard Sontag, R.J. Bernardino, J.P. Noronha,Microchem J 96 (2010) 225237.
4.S. Pedersen-Bjergaard, K.E. Rasmussen, Anal Chem 71 (1999)26502656.