A Simple and Quick Method for the Determination of Pesticides in Environmental Water by HF-LPME-GC/MS

Hindawi Publishing Corporation Journal of Analytical Methods in Chemistry Volume 2016, Article ID 7058709, 11 pages http://dx.doi.org/10.1155/2016/7058709 Research Article A Simple and Quick Method for the Determination of Pesticides in Environmental Water by HF-LPME-GC/MS Helvécio C. Menezes,1 Breno P. Paulo,1 Maria José N. Paiva,2 and Zenilda L. Cardeal1 1 Departamento de Quı́mica, ICEx, Universidade Federal de Minas Gerais, Avenida Antônio Carlos, 6627-31270901 Belo Horizonte, MG, Brazil 2 Universidade Federal de São João Del Rei, Avenida Sebastião Gonçalves Coelho 400, Chanadour, 35501-296 Divinópolis, MG, Brazil Correspondence should be addressed to Zenilda L. Cardeal; Received 10 May 2016; Revised 18 August 2016; Accepted 1 September 2016 Academic Editor: Yolanda Moliner Martı́nez Copyright © 2016 Helvécio C. Menezes et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. This paper describes a simple and quick method for sampling and also for carrying out the preconcentration of pesticides in environmental water matrices using two-phased hollow fiber liquid phase microextraction (HF-LPME). Factors such as extraction mode, time, solvents, agitation, and salt addition were investigated in order to validate the LPME method. The following conditions were selected: 6 cm of polypropylene hollow fiber, ethyl octanoate as an acceptor phase, and extraction during 30 min under stirring at 200 rpm. The optimized method showed good linearity in the range of 0.14 to 200.00 𝜇g L−1 ; the determination coefficient (𝑅2 ) was in the range of 0.9807–0.9990. The LOD ranged from 0.04 𝜇g L−1 to 0.44 𝜇g L−1 , and LOQ ranged from 0.14 𝜇g L−1 to 1.69 𝜇g L−1 . The recovery ranged from 85.17% to 114.73%. The method was applied to the analyses of pesticides in three environmental water samples (a spring and few streams) collected in a rural area from the state of Minas Gerais, Brazil. 1. Introduction The extensive use of pesticides harms the soil [1–4], air [5, 6], food [7–10] surface and ground waters [11–14], and quality causing serious impacts on the environment and on human health. In natural waters pesticide residues are present at very low levels and can be degraded when submitted to lower pH levels or exposed to solar radiation [15]. Furthermore the complexity of environmental matrices and large variations in physical and chemical properties of the target compounds requires the use of sensitive and selective techniques. Several analytical techniques, such as high-performance liquid chromatography (HPLC) [16, 17], gas chromatography (GC) [18, 19], micellar electrokinetic chromatography (MEKC) [20, 21], enzyme-linked immunosorbent assays (ELISA) [22–24], and gas and liquid chromatography coupled to mass spectrometry (GC/MS, LC-MS) [25, 26], have been used for analyses of pesticides in different matrices. The chromatographic techniques combine separation capabilities with sensitivity from the mass systems such as ion trap (IT), triple quadrupole (QqQ), and time of flight (TOF). However, these techniques still remain as challenges related to low detection limits, the variety of pesticides classes, and sample preparation. The analytes extraction in chromatographic analysis is critical to the method’s performance since it enables the elimination of possible array interferences and the preconcentration of analytes. Traditional extraction methods such as solid phase extraction (SPE) [27, 28] and liquid-liquid extraction (LLE) are multistage consuming toxic solvents and require a long time to execute. Solid phase microextraction (SPME) [29–31] is a technique that is based on the partition between the analyte present in the matrix and the fiber coating over a small fused silica rod. This technique is solvent-free and gathers in a single step extraction and preconcentration. However problems such as low resistance, short lifetime, and high cost remain. Recently, several materials have been proposed to increase the strength and durability of SPME coatings such as carbon materials [32]. Hollow fiber liquid phase microextraction (HFLPME) [33–37] and dispersive liquid-liquid microextraction 2 (DLLME) [38, 39] have been used for the concentration and clean-up step of pesticides analyses in waters. HF-LPME was developed by Pedersen-Bjergaard and Rasmussen [40] and has been used by many researchers in recent years due to its low cost, which enables the rejection of the material after use, eliminating problems of cross-contamination or low reproducibility as well as its decreased consumption of organic solvents. Moreover, the process is simple and a clean-up step is not necessary and can be applied to a variety of arrays reaching high enrichment factors [41]. The technique consists of a capillary porous hydrophilic fiber, impregnated with organic solvent and its interior filled with an acceptor phase, so that it does not come into direct contact with the matrices allowing for the application of agitation during extraction [42]. HF-LPME can be used in two or three phases. With two phases the analyte is extracted from the donor through an organic solvent immiscible in water that fills the membrane pores passing to the acceptor stage, which corresponds to the same solvent [43]. With three phases the analyte is extracted from a donor phase through an organic solvent immiscible in water for an aqueous solution (acceptor phase) inside the fiber. The organic phase acts as a barrier preventing contact between the phases. Despite the extensive use of HF-LPME for extraction of pesticides in water [33, 44, 45], the reported studies using GC/MS are generally for just one pesticide class. Therefore, this study presents the development of a simple and low-cost two-phase HF-LPME methodology for multiresidue microextraction of organophosphorus, phthalimides, organochlorines, and triazoles pesticides from environmental water using GC/MS. The pesticides selected were parathion-methyl (O,O-dimethyl-O-p-nitrophenyl phosphorothioate), chlorpyrifos (O,Odiethyl O-3,5,6-trichloro-2-pyridyl phosphorothioate), captan (N-(trichloromethylthio)cyclohex-4-ene-1,2-dicarboximide), procymidone (N-(3,5-dichlorophenyl)-1,2-dimethylcyclopropane-1,2-dicarboximide), 𝛼-endosulfan (1,4,5,6,7,7hexachloro-8,9,10-trinorborn-5-en-2,3-ylenebismethylene sulfite), prothiofos ((RS)-(O-2,4-dichlorophenyl O-ethyl S-propyl phosphorodithioate)), cyproconazole ((2RS,3RS; 2RS,3SR)-2-(4-chlorophenyl)-3-cyclopropyl-1-(1H-1,2,4-triazol-1-yl)butan-2-ol), ethion (O,O,O󸀠 ,O󸀠 -tetraethyl S,S󸀠 methylene bis(phosphorodithioate)), triazophos (O,O-diethyl O-1-phenyl-1H-1,2,4-triazol-3-yl phosphorothioate), and phosmet (O,O-dimethyl S-phthalimidomethyl phosphorodithioate). The main parameters affecting the extraction efficiency were optimized using GC/MS determination. The procedure prese (...truncated)