Optimization of Headspace Solid-Phase Microextraction for the Determination of Pesticide Residues in Vegetables and Fruits

Abstract

Pesticides, including organochlorine pesticides (OCPs) and organophosphorous pesticides (OPPs) are examples of wellknown environmental contaminants. OPPs are used as a substitute for OCPs in many countries nowadays because they can degrade more easily in the environment. Although OPPs as a whole are not the most toxic pollutants, they can be traced to a wide range of surface water, fruits, vegetables and foodstuff. 1For fast monitoring of the environmental contamination caused by OCPs and OPPs and to accomplish risk assessment, more sensitive, rapid and simple analytical methods are paramount.Liquid-liquid extraction (LLE) and solid-phase extraction (SPE) are the most popular methods for extracting pesticides. However, they are time consuming and labor-intensive, and require large volumes of sample and solvents. In addition, because pesticides generally are present at ppt levels, mixed with other contaminants at higher concentrations, interfering compounds can produce extraneous peaks. LLE and SPE can carry contaminants into the final sample, producing a high background. 2-4Solid-phase microextraction (SPME), developed by Kataoka et al.,5 has received an increasing amount of attention at the analytical level in numerous scientific disciplines. 6 It is simple 6,7 and, as will be discussed later, offers great flexibility. In comparison with direct SPME, headspace (HP) SPME can shorten the time of extraction significantly because the diffusion rate of the analytes in gaseous phase is faster than that in the aqueous phase.1 Only a few references on the application of HS-SPME for the determination of OCPs and OPPs in fruit and vegetable samples can be found. 8,9 Most applications are based on the preparation of fruit or vegetable juices and analysis of target compounds by directly dipping of the SPME fibers into the slurry. [9][10][11][12][13][14] However several disadvantages related to fiber stability and sensitivity have been pointed out. Such problems can be overcome if headspace SPME is applied. Since the fiber is not in contact with the sample, background adsorption and matrix effects can be reduced, which also enhances the life expectancy of the SPME fibers. The objectives of this study are to evaluate the HS-SPME process by comparing two coating materials and to optimize the main parameters affecting the HS-SPME. Finally, we intended to develop an efficient multi-residue method on the basis of HS-SPME to extract each selected pesticide in fruit and vegetable samples. Experimental Chemicals and reagentsEight pesticides standards which are popular used by local farmers in vegetable and fruit cultivation 15 were > 95% pure and were purchased from AccuStandard Inc., USA. Stock solutions of each pesticide were prepared. Working standard solutions were prepared daily by volume dilution in distilled water. In the calibration and quantitation studies, an internal standard, 1-chloro-4-fluorobenzene, 200 mg/L which is effective as a surrogate to compensate the data of all 8 kinds of pesticides was added to each sample...

A novel optimised and validated method for analysis of multi-residues of pesticides in fruits and vegetables by microwave-assisted extraction (MAE)–dispersive solid-phase extraction (d-SPE)–retention time locked (RTL)–gas chromatography–mass spectrometry with Deconvolution reporting software (DRS)

“…The main focus is on simplification, miniaturization and improvement of sample extraction and cleanup with universal micro extraction procedures, namely supercritical fluid extraction (SFE) (Nerin, Batlle, & Cacho, 1998), matrix solid-phase dispersion (MSPD) (Blasco, Font, & Pico, 2004;Chai, Tan, & Asha, 2008), solidphase extraction (SPE) on cartridges (Abhilash, Jamil, & Singh, 2007;Barriada-Pereira et al, 2004) to replace liquid-liquid extraction (LLE), Soxhlet extraction, enzyme-linked immunosorbent assay (ELISA) (Watanabe, Yoshimura, Yuasa, & Nakazawa, 2001) and microwave-assisted extraction (Barriada-Pereira et al, 2003;Gfrerer & Lankmayr, 2004). Among these extraction methods, MAE has become a popular technique in recent years.…”

Modified Dispersive Liquid-Liquid Microextraction Using Green Solvent for Determination of Polycyclic Aromatic Hydrocarbons (Pahs) in Vegetable Samples

“…From the Figure 1, 1-bromo-3-methylbutane yield the highest average recovery percentage (75.53 %) compare to other extraction solvents. Meanwhile, other extraction solvents failed to obtain the acceptable recovery range (70 -120 %) set up by the International Conference on Harmonisation (ICH) on the validation of analytical procedures [7]. 1 -bromo-3-methylbutane solvent was able to extract all the desired analytes well in the acceptable recovery range from the liquid matrices.…”

Validation of a headspace solid-phase microextraction procedure with gas chromatography-electron capture detection of pesticide residues in fruits and vegetables

“…The development of the HS-SPME technique for trace analysis of multiresidue pesticides in fruits and vegetables without any pretreatment of the samples has been demonstrated in the previous paper (Chai et al, 2008). The developed HS-SPME method has resulted in a drastic reduction of the analysis time and organic solvent consumption.…”

“…In a previous paper (Chai, Tan, & Asha, 2008), the optimisation of a HS-SPME extraction and thermal desorption procedure coupled to gas chromatography with electron capture detection for the determination of 8 pesticide residues in fruits and vegetables was carried out. A 100 lm polydimethylsiloxane (PDMS) coated fibre was found to be the most efficient in extracting the investigated pesticide residues.…”