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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

*helveciomenezes@hotmail.comKeywords: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.