Combination of Extraction by Silylated Vessel-Dispersive Liquid–Liquid Microextraction as a High-Enrichment Factor Technique: Optimization and Application in Preconcentration of Some Triazole Pesticides from Aqueous Samples Followed by GC-FID Determination

Abstract

This study describes an extraction method based on silylated extraction vessel-dispersive liquid-liquid microextraction (SEV-DLLME) for preconcentration of some triazole pesticides (penconazole, hexaconazole, tebuconazole, diniconazole, triticonazole, and difenconazole) from aqueous samples. For this purpose, the interior surface of funnel-shaped extraction vessel is activated by concentrated NaOH and HCl solutions, silylated by trimethylchlorosilane (TMCS) and used in extraction of the analytes from a relatively high volume of aqueous sample. The adsorbed analytes are desorbed by methanol, which acts as a dispersive solvent in the following DLLME method. In the first step, the effects of different factors i.e., concentrations of NaOH, HCl, and silylated agent and their contact times were studied using central composite design (CCD) and response surface method. Extraction time, extraction solvent (chloroform) volume, dispersive solvent (methanol) volume, centrifugation rate and time, and salting-out effect in DLLME procedure were optimized in the same way using CCD, in the second step. High enrichment factors (EFs) (more than 1,000 in most cases) and low detection limits (at sub lg L -1 level) are attainable by using gas chromatography-flame ionization detection. The repeatability and reproducibility of the proposed method are good and the relative standard deviations (RSD %) for six repeated experiments (C = 100 lg L -1 of each pesticide) are less than 7.25%. Finally, the method was successfully applied in determination of analytes in some aqueous samples such as wastewater, well water, and some fruit juice samples.

Vortex-Assisted Ionic Liquid Dispersive Liquid-Liquid Microextraction Coupled with High-Performance Liquid Chromatography for the Determination of Triazole Fungicides in Fruit Juices

“…Considering the fact that fruit juices are becoming more and more popular, it is necessary to develop sensitive and selective methods for the analysis of triazole fungicide residues usually present in trace amounts. Many chromatographic analytical methods for the trace determination of triazole fungicide residues in water and fruit juice samples included gas chromatography (GC) (Bordagaray et al 2011;Farajzadeh et al 2010Farajzadeh et al , 2011Farajzadeh et al , 2012Farajzadeh and Khoshmaram 2013;Freitas et al 2014;Li et al 2014;Sarafraz-Yazdi et al 2012), GC with mass spectrometry (GC-MS) (Farajzadeh et al 2012;Freitas et al 2014;Sarafraz-Yazdi et al 2012), GC with tandem mass spectrometry (GC-MS/MS) (Li et al 2011, highperformance liquid chromatography (HPLC) (Bordagaray et al 2013(Bordagaray et al , 2014Gao et al 2012;Luo et al 2013;Wang et al 2011;Ye et al 2012), HPLC with tandem mass spectrometry (HPLC-MS/MS) (Juan-Garcia et al 2004;Li et al 2013;Wang et al 2014;Zhang and Xu 2014), and capillary electrophoresis (CE) (Chicharro et al 2003;Rodriguez et al 2001;Wu et al 2001). On the other hand, quick and effective sample preparation coupled with a reliable analytical method is imperative.…”

Separation and Preconcentration by Dispersive Liquid–Liquid Microextraction Procedure: Recent Applications

“…Gas Chromatography DLLME has been used in conjunction with gas chromatography-flame ionization detector (GC-FID) for the analysis of volatile organic compounds [12], drug [13], nitrotoluenes [14], parabens [15], phthalate esters [16], pyrethroids [17,18], triazole pesticides [19,20] and polycyclic aromatic hydrocarbons [23].…”

“…Water and fruit juice samples [19] Six triazole pesticides 1 mL methanol 25 lL Water and fruit juice samples [20] Five triazole pesticides 1 mL acetonitrile 40 lL Milks [21] 3.9-10.8…”

“…Farajzadeh et al [19] develop an extraction method based on silylated extraction vessel-DLLME. For this purpose, the interior surface of funnel-shaped extraction vessel is activated by concentrated NaOH and HCl solutions, silylated by trimethylchlorosilane and used in extraction of the analytes from a relatively high volume of aqueous sample.…”

Ultrasound-Assisted Dispersive Liquid–Liquid Microextraction Combined with Low Solvent Consumption for Determination of Polycyclic Aromatic Hydrocarbons in Seawater by GC–MS

“…Several different types of LPME have been developed, such as headspace LPME [15], hollow fiber LPME (HF-LPME) [16], solvent bar LPME (SB-LPME) [17], and dynamic LPME [18], continuous-flow LPME (CF-LPME) [19], liquidliquid-liquid microextraction (LLLME) [20], single drop microextraction (SDME) [21], and dispersive liquid-liquid microextraction (DLLME) [22]. This last method, DLLME, not only gives good extraction efficiencies but also reduces extraction time and organic solvent consumption [23]. Nevertheless, some drawbacks, such as droplet instability and relatively low precision are often reported [24].…”