A solid-phase microextraction fiber coated with diglycidyloxycalix[4]arene yields very high extraction selectivity and sensitivity during the analysis of chlorobenzenes in soil

Abstract

A novel fiber coated with sol-gel (5,11,17,23-tetra-tert-butyl-25,27-dihydroxy-26,28-diglycidyloxycalix [4]arene/hydroxy-terminated silicone oil; diglycidyloxy-C[4]/OH-TSO) was prepared for use with headspace solidphase microextraction (HS-SPME) combined with gas chromatography (GC) and electron capture detection (ECD), which was applied in order to determine nine chlorobenzenes in soil matrices. Due to the improved fiber preparation, which increases the percentage of calixarene in the coating, the new calixarene fiber exhibits very high extraction selectivity and sensitivity to chlorine-substituted compounds. Various parameters affecting the extraction efficiency were optimized in order to maximize the sensitivity during the chlorobenzene analysis. Interferences from different soil matrices with different characteristics were investigated, and the amount extracted was strongly influenced by the matrix. Therefore, a standard addition protocol was performed on the real soil samples. The linear ranges of detection for the chlorobenzenes tested covered three orders of magnitude, and correlation coefficients >0.9976 and relative standard deviations (RSD) <8% were observed. The detection limits were found at sub-ng/g of soil levels, which were about an order of magnitude lower than those given by the commercial poly(dimethylsiloxane) (PDMS) coating for most of the compounds. The recoveries ranged from 64 to 109.6% for each analyte in the real kaleyard soil matrix when different concentration levels were determined over the linear range, which confirmed the reliability and feasibility of the HS-SPME/ GC-ECD approach using the fiber coated with diglycidyloxy-C[4]/OH-TSO for the ultratrace analysis of chlorobenzenes in complex matrices.

Determination of Polycyclic Aromatic Hydrocarbons in Vegetables by Headspace SPME-GC

“…In the case of liquid or high moisture samples, an increase of ionic strength (the 'salting-out' effect) and pH adjustment are the typical approaches applied. The addition of organic solvent or water to samples to decrease the strong sorption of analytes has also been reported [31,32]. The addition of six solvents of different polarities (methanol, ethanol, dichloromethane, acetonitrile, n-hexane, and acetone) was tested during this step under the optimized extraction conditions, aiming at enhancing the transfer of PAHs from vegetable to the headspace.…”

β-cyclodextrin functionalized meso-/macroporous magnetic titanium dioxide adsorbent as extraction material combined with gas chromatography-mass spectrometry for the detection of chlorobenzenes in soil samples

“…For pretreatment by MSPE, choosing an appropriate adsorbent is a critical step towards satisfactory recovery [13]. Interestingly, various adsorbent types, such as silica-based materials, C18 (octadecyl), florisil, alumina, poly-di-methyl-siloxane (PDMS), PSA (Primary secondary amine), have been used for detecting CBs in different samples [3,[14][15][16][17]. However, these adsorbents do not have good selectivity towards CBs.…”

“…Chlorobenzenes (CBs) are a class of environmental pollutants widely used as pesticides, deodorants, industrial solvents, heat transfer agents and chemical intermediates, which can easily enter the environment at trace level and may be found in soil as well as biological tissues [1][2][3]. The biological accumulation of CBs can be expected in soil because of their difficult degradation and hydrophobic properties [3,4].…”

“…The biological accumulation of CBs can be expected in soil because of their difficult degradation and hydrophobic properties [3,4]. Therefore, in recent years, increasing concern has been raised by scientists and the public about CBs in soil.…”

A critical review of the state of the art of solid-phase microextraction of complex matrices I. Environmental analysis

“…In SPME, the extraction phase can be exposed 59 directly to the sample media (direct immersion, DI) or to its headspace (HS). When the SPME coating is placed directly in contact 60 with the sample, the amount of analyte extracted at equilibrium (n e ) can be described as [2]: 61 62 (1) 63 In Equation (1), n e is proportional to the distribution coefficient of the analyte between the coating and sample matrix (K fs ), the 64 volume of the extraction phase (V f ), the volume of the sample (V s ) and the analyte concentration in the sample matrix (C s ). Equation…”