# Ionic liquid coating for stir bar sorptive extraction and its application for extraction and nontargeted screening analysis via TD-GC-Orbitrap-HRMS of pollutants in river water

Amel Meziani, Ouassila Ferroukhi, Valerie Peulon-Agasse, Pascal Cardinael

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Amel Meziani, Ouassila Ferroukhi, Valerie Peulon-Agasse, Pascal Cardinael. Ionic liquid coating for stir bar sorptive extraction and its application for extraction and nontargeted screening analysis via TD-GC-Orbitrap-HRMS of pollutants in river water. Journal of Chromatography A, 2025, 1742, pp.465623. 10.1016/j.chroma.2024.465623. hal-04936180

HAL Id: hal-04936180

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Submitted on 23 Jan 2026

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# Ionic liquid coating for stir bar sorptive extraction and its application for extraction and nontargeted screening analysis via TD-GC-Orbitrap-HRMS of pollutants in river water

Amel Meziani<sup>a,b</sup>, Ouassila Ferroukhi<sup>b,c</sup>, Valerie Peulon-Agasse<sup>a</sup>, Pascal Cardinael<sup>a,*</sup>

## ARTICLE INFO

**Keywords:**

SBSE

Ionic liquid

Natural waters

GC-HRMS-Orbitrap

Organic contaminants

## ABSTRACT

In this study, a novel imidazolium-based ionic liquid (IL) coating was developed for stir bar sorptive extraction (SBSE) using a sol-gel method. The effects of different counterions, conditioning temperatures and polymer compositions were investigated. The stir bar with bis((trifluoromethyl)sulfonyl) amide 1-butyl-3-(3-(triethoxy-silyl)propyl)-1H-imidazol-3-ium showed good mechanical and thermal stability with high resistance to water solubilization. The extraction efficiency of the IL-coated stir bar was evaluated on a mixture of 11 compounds presenting a wide range of polarities (log K<sub>o/w</sub> values between 0.65 and 7.21) using thermodesorption gas chromatography coupled with Orbitrap high-resolution mass spectrometry (TD-GC-Orbitrap-HRMS). The results showed that extraction yields were increased for the IL-stir bar. In contrast, the commercial polydimethylsiloxane (PDMS) stir bar resulted in decreased yields with salt addition, particularly for compounds with log K<sub>o/w</sub> > 4. SBSE of contaminants was performed on natural waters collected from France, followed by nontargeted analysis using TD-GC-Orbitrap-HRMS. The results revealed the detection of over 1,000 compounds, with 334 compounds annotated after deconvolution. The IL-stir bar with the addition of NaCl specifically extracted five times more compounds (167 compounds) than did the commercial PDMS stir bar (29 compounds) and more than 10 times more with the addition of NaCl with the PDMS stir bar (15 compounds). Various pollutants, including pesticides, personal care products, polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs), were identified. The annotations of the identified compounds were classified according to a level of confidence based on comparisons of retention indices, match library spectra and high-resolution mass filters.

## 1. Introduction

For more than two decades, the occurrence of emerging and persistent organic pollutants, which have largely been outside the scope of monitoring and regulation, in the aquatic environment has sparked growing interest [1]. The extensive daily use of chemicals in several fields, such as industry, domestic households and medicine, has led to the bioaccumulation of these pollutants, which include different groups of compounds, such as plasticizers, drugs, pesticides, pharmaceuticals and personal-care products (PPCPs). Emerging organic contaminants (EOCs) have been in use for a long time; however, their high ecotoxico-cological effects on human health and the environment have only been investigated recently. Therefore, the study of this new class of pollutants has become a major subject among researchers [2]. Several studies have

demonstrated the presence of various pollutants from leaking septic tanks and landfills in groundwater [3–5]. Other studies have focused on the presence of these pollutants in wastewater treatment plant effluents [6–8] and surface waters [9,10]. This research became possible because of the improved techniques of extraction and detection (gas and liquid chromatography coupled with high-resolution mass spectrometry). Most EOC concentrations in aquatic systems are very low (in the range of ng/L up to µg/L), and for wastewater treatment plants, if the concentration is high, it ranges between 0.1 and 10 µg/L [11].

Water samples such as wastewaters are complex mixtures and may contain interferents that require extraction procedures to achieve low limits of detection (fixed at approximately µg/L by the European Union [12]). For a long time, liquid-liquid extraction (LLE) was the most commonly used sample preparation technique. However, this method is

<footnote><sup>a</sup> Univ Rouen Normandie, FR3038, SMS, UR 3233, F-76000 Rouen, France</footnote>

<footnote><sup>b</sup> Laboratoire de Chromatographie, Faculté de Chimie, USTHB, BP 32 EL-Alia, Alger, 16111 Algeria</footnote>

<footnote>* Corresponding author.</footnote>

<footnote>E-mail address: pascal.cardinael@univ-rouen.fr (P. Cardinael).</footnote>
time-consuming and requires the use of large volumes of organic solvents. As an alternative, solid-phase extraction (SPE) was introduced, and it allowed for considerably reduced solvent consumption. This sample preparation has been used to extract different pollutants, such as pesticides, polyaromatic hydrocarbons (PAHs) and PPCPs, from water samples [13]. Nevertheless, to achieve detection limits below ng/L, this technique requires sample volumes from 5 to 10 mL [14], the extract must be concentrated to a small volume (<1 mL), or a large-volume injection must be performed. However, the use organic solvents for elution step remains necessary. Miniaturized solvent-less extraction techniques, such as dispersive liquid-liquid microextraction (DLLME) [15], solid phase microextraction (SPME) [16], microextraction-packed sorbent (MEPS) [17] and stir bar sorptive extraction (SBSE) [18], have recently been introduced, allowing extraction and preconcentration in a single step. The latter is based on sorption and partitioning between the sorption phase and aqueous phase [19]. These techniques have offered considerable advantages for trace analysis because they can be directly coupled to online analysis, ensuring the complete transfer of the extract to the analytical system. These factors enhance the sensitivity and minimize potential analyte loss. Moreover, the enrichment factor for SBSE is greater than that for SPME because the volume of the extraction phase on the stir bar is larger than that on the SPME fiber (50- to 250-fold greater). Therefore, limits of detection (LODs) below ng/L can be reached, especially for solutes with hydrophobic characteristics [20]. For example, Popp et al. demonstrated that when only 8 mL of aqueous sample was used, the LODs of 25 PCBs in water were <1 ng/L (LOD: 0.05-0.15 ng/L) using SBSE-TD-GC-MS [21].

The main limitation of SBSE is the lack of a variety of coatings in terms of polarity. Currently, only polydimethylsiloxane (PDMS), ethylene glycol (EG)-silicone and polyacrylate (PA) coatings are commercially available, which limits the extraction of solutes from water when the logarithm of the octanol-water partitioning coefficient ($\log K_{ow}$) is < 2 [22]. To overcome this limitation, different approaches, such as SBSE combined with a freeze concentration called ICECLES, have been proposed. In this case, SBSE was performed while the sample was frozen from the bottom of the vial to the top, which increased the analyte extraction yield [23]. Moreover, solvent-assisted SBSE (SA-SBSE) was proposed, where a solvent is used to modify the PDMS phase polarity to increase the recoveries of polar solutes [24].

Another alternative is the development of novel extraction phases with better affinities for polar compounds. However, the preparation of new coatings requires good mechanical stability and a sufficient amount of stationary phase (between 50 and 300 µL) [25] to increase the extraction yield. Approaches such as sol-gel, polymerization, adhesion and monolith preparation are the most common methods used to prepare stir bar coatings [26]. Various materials have been introduced as sorbents for stir bar coatings to improve SBSE performance [26]. Carbon-based materials have been widely used as sorbents for solid-phase extraction because of their high specific surface area and good thermal stability. Zhang et al. [27] used graphene immobilized onto polytetrafluoroethylene (G-PTFE) to prepare an SBSE coating on a stir bar after surface pretreatment with polydopamine. The stir bar showed good thermal stability (300 °C), and PAH extraction obtained yields ranging from 18 to 62 %. Nevertheless, the extraction kinetics were relatively low (approximately 2 h to reach equilibrium). Metal-organic frameworks (MOFs) [28] have also been used as sorbents for SBSE, and the coating was performed using the sol-gel method with in situ chemical bonding. The combination of azacyclic ligands such as imidazole zeolite skeleton materials (ZIFs) results in better properties, including a porous uniform structure, several functional groups and high thermal and mechanical stabilities [29]. Sun et al. [30] used an adhesion approach to produce a coated stir bar with a synthesized covalent organic framework based on 1,3,5-tris(4-aminophenyl)benzene and 2, 5-bis(hexyloxy)terephthalaldehyde as precursor materials. This stir bar was used to analyze four estrogens in water samples and an enrichment factor ranged from 39 to 49 was obtained, while the theoretical EF was

estimated to be 50-fold. Xiao et al. [31] prepared a MIL-101-Cr-NH₂ stir bar using a sol-gel method and analyzed organophosphorus pesticides (OPPs) from environmental water samples. The stir bar showed good mechanical stability, as it was reused approximately 50 times. Other materials, such as porous organic polymers (POFs) [32,33], molecular imprinted polymers (MIPs) [34] and ionic liquids (ILs) [35], have also been studied to prepare SBSE coatings to increase the extraction yield of polar organic compounds.

ILs consist mainly of a large organic cation and smaller organic or inorganic anions. These compounds present various properties, such as good thermal stability, hydrophobic and hydrophilic properties and the ability to tune their selectivity [36]. ILs present a high affinity for polar, nonpolar and aromatic compounds because of the $\pi$-$\pi$ linkages and the hydrogen bonds from different functional groups of the ILs [36]. An IL-bonded sol-gel coating using 1-allylimidazolium tetrafluoroborate ([AIMb][BF₄]) as a monomer was prepared to determine three nonsteroidal anti-inflammatory drugs in environmental water, human urine and milk samples via SBSE-HPLC-UV [37]. Compared with those of the PDMS-based or monolithic coatings, the extraction efficiency and kinetics of adsorption/desorption were greater. Wang et al. [35] prepared ionic liquid-based organic polymers as SBSE coatings using in situ polymerization. This approach was combined with HPLC-MS/MS to analyze three chlorophenoxy acid herbicides in soil samples, and the method demonstrated good extraction yields (49.5-51.5 %) and an enrichment factor of 198-206. Chisvert and coworkers [38,39] used a magnetic ionic liquid (MIL) and a neodymium-core magnetic stir bar into the sample allowing for the stir bar coating by physical forces. However, at high stirring rate, the rotational forces surpassed the magnetic field and the MIL was disperses into the sample solution.

In our study, the main goal was to develop a new ILs coating for SBSE using the sol-gel method to improve the extraction yield of polar compounds while maintaining good extraction efficiency for apolar compounds. The yields obtained with these newly prepared stir bars will be compared to those obtained with commercial PDMS stir bars using a mixture of 11 target compounds with $log K_{o/w}$ values between 0.65 and 7.21 to cover a wide range of compound polarities. The prepared IL-stir bar will also be tested on real water samples (Robec River, France) to extract emerging and/or persistent pollutants. A nontargeted screening TD-GC-Orbitrap-HRMS method was developed, and the pollutants were identified processed using Compound Discoverer software. The identified compounds were annotated according to the confidence scale proposed by Miller et al. [40].

## 2. Materials and methods

### 2.1. Chemicals and reagents

Tetraethyl orthosilicate (TEOS), anthracene and carbazole were purchased from Acros Organics (Morris Plains, New Jersey, USA). Dichloromethane (DCM) and sodium hydroxyde were obtained from Ficher Chemical (Waltham, Massachusetts, USA). Acenaphthene and fluorene were purchased from Prolabo (Fontenay-Sous-bois, France). Phenanthrene, pyridine, polydimethyl siloxane and atrazine were purchased from Sigma-Aldrich (St. Louis, Missouri, USA). Ultrapure water (18.2 MΩ.cm) was obtained from a Milli-QBwater system (Millipore Ltd., Bedford, MA, USA). Trifluoroacetic acid was purchased from Merck (Darmstadt, Germany). Anthraquinone, 2-fluorobiphenyl, coumarin, 9-nitroanthracene, 2-phenylbenzothiazol, 2-butylthiophene, PCB-138 and PCB-101 were purchased from Dr. Ehrenstorfer GmbH (Augsbourg, Germany).

### 2.2. Preparation of IL-coated stir bars

Two imidazolium-based ionic liquids (1-butyl-3- (3-triéthoxysilyl) propyl)-1H-imidazol-3-ium chloride [TESBPIM][Cl] and bis((trifluoromethyl)sulfonyl)amide 1-butyl-3-(3-(triethoxysilyl)propyl)-1H-
<table><caption>**Table 1**
Different prepared stir bars and conditions.</caption><thead><tr><th rowspan="2">Sorptive stir bar</th><th colspan="2">Polymers</th><th rowspan="2">Deposition amount (mg)</th><th rowspan="2">Conditioning temperature</th><th rowspan="2">Stability</th></tr><tr><th>ILs (%)</th><th>PDMS(%)</th></tr></thead><tbody><tr><td>1</td><td>[TESBPIM][Cl]</td><td>/</td><td>30.0</td><td rowspan="4">30 °C to 240 °C and hold for 3 h</td><td>Decomposed</td></tr><tr><td>2</td><td>[P<sub>444</sub>TES] [Cl]</td><td>/</td><td>44.5</td><td>Very soft and decomposed</td></tr><tr><td>3</td><td>[TESBPIM][NTF<sub>2</sub>]</td><td>/</td><td>57.2</td><td>Cracked and decomposed</td></tr><tr><td>4</td><td>[TESBPIM][NTF<sub>2</sub>]</td><td>25</td><td>43.4</td><td>Nonhomogenous</td></tr><tr><td>5</td><td>[TESBPIM][NTF<sub>2</sub>]</td><td>50</td><td>71.7</td><td>Nonhomogenous</td><td></td></tr><tr><td>6</td><td>[TESBPIM][NTF<sub>2</sub>]</td><td>/</td><td>31.7</td><td>Hard and stable</td><td></td></tr><tr><td>7*</td><td>[TESBPIM][NTF<sub>2</sub>]</td><td>/</td><td>47.4</td><td>Hard and stable</td><td></td></tr></tbody></table>

imidazol-3-ium [TESBPIM][NTF₂]) and a phosphonium-based ionic liquid (tributyl(3-(triethoxysilyl)propyl) phosphonium chloride [P₄₄₄TES] [Cl]) were synthesized according to previous laboratory work [41]. The three ILs were selected due to their high thermal stability (up to 325 °C) [42].

Noncoated glass-encased magnetic stir bars (10 mm length) obtained from Gerstel (Germany) were cleaned with water followed by washing with DCM and then dipped into a solution of NaOH (1 mol/L) for 8 h. Subsequently, the stir bars were cleaned with water, dipped again in a solution of HCl (0.1 mol/L) and then dried at 60 °C overnight. The sol-gel process was used to prepare the IL coatings. The sol solution of the IL was composed of 200 mg of the IL, 150 µL of TEOS, 200 µL of 95 % TFA and 1 mL of DCM. The treated bare bars were immersed in the solution for 5 min, removed, and dried at room temperature. This procedure was repeated several times until a thick coating was formed. The coated stir bars were conditioned using a conditioning unit under a nitrogen atmosphere (Gerstel, TC 2, Germany), and the following temperature program was used from 30 °C to 200 °C and held for 2 h.

To evaluate the coating film homogeneity, microscopic images were obtained using a Nikon Eclipse LV100 microscope (maximum magnification: 1000 ×), coupled to a CCD camera connected to a computer. The data acquisition was performed via NIS-Elements D software (version 3.1).

DRIFT spectra were obtained using a PerkinElmer (Norwalk, CT, USA) Spectrum 100. The IL sample was placed in a 2 mm diameter disk. The spectra, which consisted of 256 scans, were acquired at a resolution of 4 cm⁻¹ and over the range of 4000–600 cm⁻¹.

<figure><img src="image_4.png" /><figcaption>**Fig. 1.** Chemical structure of the ILs (a) tributyl (3-(triethoxysilyl)propyl) phosphonium chloride [P₄₄₄TES] [Cl], (b) bis((trifluoromethyl)sulfonyl)amide 1-butyl-3-(3-(triethoxysilyl)propyl)-1H-imidazol-3-ium [TESBPIM][NTF₂] and (c) 1-butyl-3-(3-(triethoxysilyl)propyl)-1H-imidazol-3-ium chloride [TESBPIM][Cl].</figcaption></figure>

## 2.3. Stir bar sorptive extraction procedure

Stirring extraction and TD were used in this work. Aqueous samples (10 mL) containing 11 target compounds (log K₀/w values between 0.65 and 7.21) were placed in 20 mL vials at room temperature. The prepared IL-stir bar was stirred in the sample mixture for 1 h. After extraction, the stir bar was dried and placed in a glass desorption tube. The thermodesorption was performed using a TDU 3.5 + 5 Gerstel thermal desorption unit (Mulheim, Germany) with the following temperature program: from 40 °C (held for 1 min) at 100 °C/min to 280 °C (held for 5 min) with 15.5 mL/min desorption flow. The same methodology was applied for commercial PDMS stir bars to compare the extraction yields.

The environmental water samples were collected from the Robec River (49.441515312762, 1.099119438792342 Rouen, France). The 500 mL water samples were filtered through a 0.45 µm nylon filter and then stored in a refrigerator at 4 °C. A volume of 10 mL of filtered water with 70 mg of NaCl was used for SBSE using the prepared IL-stir bar at room temperature for 1 h. The same procedure was applied using a commercial PDMS stir bar once and without NaCl addition. The stir bars were thermally desorbed under the abovementioned conditions. Blank analysis of IL-stir bar and PDMS ones were performed before sample analysis highlighted similar noise.

## 2.4. GC-Q-Orbitrap analyses

Analyses were performed using a GC-Q-Orbitrap system (Q Exactive, Thermo Scientific, Bremen, Germany) comprising a Gerstel MPS (multipurpose sampler) (Mülheim, Germany) autosampler, a trace 1310 GC with a programmable temperature vaporizer (PTV) injector, an electron ionization (EI) source, and a hybrid Q-Orbitrap mass spectrometer. The PTV cool injection system (CIS6) was used in splitless mode. The desorbed compounds were focused on a PDMS packed liner at 4 °C in the PTV inlet and programmed from 4 °C (held for 1 min) to 280 °C (held for 15 min) at 4 °C/s. The carrier gas was helium (99.999 %, Air liquid, Paris, France) at a constant flow rate of 1.0 mL/min. GC separations were performed using an Elite 5MS (60 m × 250 µm × 0.25 µm film thickness) (PerkinElmer, Waltham, Massachusetts, USA) column, and for the environmental water samples, a HP-5 MS UI (30 m × 250 µm × 0.25 µm film thickness) (Agilent Technologies, Santa Clara, USA) was used with the following temperature program: 40 °C (held for 2 min) to 320 °C (held for 5 min) at 10 °C/min. EI was performed at 70 eV with the source temperature set at 200 °C. Full-scan MS acquisition was performed in profile mode using a *m/z* range of 50–500. Nitrogen gas (Air liquid, Paris, France) was used for the C-Trap supply. The internal mass calibration (lock mass mode) was performed during the analyses using the following ions from column bleeding (*m/z*) (C₃H₉Si⁺, 73.04680; C₃H₉O₂Si₂⁺, 133.01356; C₅H₁₅O₃Si₃⁺, 207.03235; C₇H₂₁O₄Si₄⁺, 281.05114; C₉H₂₇O₅Si⁺, 355.06993). The data were reprocessed using QualBrowser 4.1, TraceFinder 4.1 and Compound Discoverer 3.3 software (Thermo Fisher Scientific, Waltham, MA, USA). The last two software programs were able to perform deconvolution and comparison

<footnote>* IL-stir bar presenting the best performance.</footnote>
<figure><img src="image_5.png" /><figcaption>**Fig. 2.** Degradation of the coated stir bars (1) with [TESBPIM][Cl] and (2) with [TESBPIM][NTf₂] after conditioning at 240°C for 3 h.</figcaption></figure>

with mass spectra and retention indices (RIs) collected from the NIST database (2.2, 2014) and the Orbitrap spectral database (Thermofisher, 2015). For the RI calculation, a standard *n*-alkane mixture from C₆ to C₂₈ was injected under the same chromatographic conditions.

# 3. Results and discussion

## 3.1. Preparation of the IL coating

To obtain a stable and long-lasting (with high thermal stability) coating of the IL on stir bars, sol–gel technology was chosen. This procedure involves several reactions starting with the hydrolysis of the monomer precursor, followed by the polycondensation of the

<figure><img src="image_6.png" /><figcaption>**Fig. 3.** Microscopy images (× 250) of a commercial PDMS-coated stir bar (a) and the prepared stir bars (number 7) using the [TESBPIM][NTf₂] IL (b), and a photography of the IL-coated stir bar and uncoated stir bar (c).</figcaption></figure>

<figure><img src="image_7.png" /><figcaption>**Fig. 4.** DRIFT spectrum of the [TESBPIM][NTf₂] ionic liquid.</figcaption></figure>
<figure><img src="image_8.png" /><figcaption>**Fig. 5.** Ratio of peak area obtained from the extraction of a mixture of 11 compounds from water using a prepared IL-stir bar and a commercial PDMS stir bar with and without NaCl addition.</figcaption></figure>

hydroxylated compounds to form a tridimensional sol-gel network. Several conditions for stir bar coating were tested, but for clarity, only some representative tests are given in Table 1 and discussed. Three different ILs were selected and used for sol-gel coating, one with a phosphonium cation ([P444TES] [Cl]) and two with an imidazolium cation with two different anions ([TESBPIM] [Cl] and [TESBPIM][NTf₂]) (Fig. 1). The physical characteristics of the obtained coatings were evaluated by visual assessment at different steps of the process. The coatings prepared using [TESBPIM] [Cl] and [P444TES] [Cl] showed good adhesion on the stir bar; however, after the conditioning step (240 °C and hold for 3 h), poor mechanical stability was observed as the coatings crumbled (numbers 1 and 2 in Table 1). A modification of their color was also observed, as shown in Fig. 2-(1). With [TESBPIM][NTf₂], the physical characteristics of the coating showed a higher mechanical stability. However, after the conditioning step, cracks were observed in the coating layer (number 3 in Table 1), and a change of the color was also observed, as shown in Fig. 2-(1). This phenomenon was attributed to thermal degradation; thus, the temperature and duration of the conditioning step were reduced to 200 °C for 2 h.

To improve the stability of the coating, a percentage of PDMS was added to the sol-gel solution at different ratios (weight percentages of 25 % and 50 %). In the presence of the PDMS, a white coating appeared on the stir bars, leading to a nonhomogeneous coating regardless of the percentage (numbers 4 and 5 in Table 1) and its decomposition during stirring. Thus, the use of PDMS did not improve the coating stability.

Finally, the use of [TESBPIM][NTf₂] with the new conditioning temperature (200 °C for 2 h) provided good mechanical stability of the coating (numbers 6 and 7 in Table 1). Fig. 3(c) shows the stir bars before and after the IL coating. The images obtained using an optical microscopy revealed the presence of gas bubbles in the coating. However, the coated film remained uniform, and no cracking was observed. The film thickness was measured at two locations of the stir bar (Fig. 3(b)) and was between 350 µm and 360 µm, demonstrating a uniform coating on the stir bar. Compared with a commercial PDMS coating (the measured film thickness was calculated to be approximately 430 µm (Fig. 3(a)), the film thickness of the prepared IL coating is satisfactory. Thus, the IL [TESBPIM][NTf₂] stir bar (7), which has the best stability, was used for the extraction test in our following tests.

The Fig. 4 shows the DRIFT spectrum of the IL [TESBPIM][NTf₂] prepared coating. Peaks in the range from 2800 to 3000 cm⁻¹ are attributed to the aliphatic CH of the butyl chain attached to the

imidazolium ring. Peaks at 2881 and 2970 cm⁻¹ are attributed to the symmetric stretching vibration of CH₃ and asymmetric stretching vibration of CH₃ respectively. The features observed above 3000 cm⁻¹ are from the C—H vibrational modes of the imidazolium ring [43]. Between 3300 and 3800 cm⁻¹ there are main bands that are due to the symmetric and asymmetric stretching vibrations of H₂O molecules and these bands tend to overlap the lower frequency bands [44].

## 3.2. Extraction tests of the prepared IL-stir bar

To evaluate the extraction efficiency of the prepared IL-stir bar, the extraction of a mixture of 11 compounds presenting a large range of polarities (log K₀/w values between 0.65 and 7.21) from water was performed using the prepared stir bar (number 7) and a commercial PDMS bar. The ratio between the peak areas obtained with the PDMS stir bar and the IL-stir bar was calculated for each compound (peak area-IL/peak area PDMS), and the results are presented in Fig. 5.

The results of the extraction test without the addition of NaCl revealed that for all the compounds, the ratio of peak area-IL/peak area-PDMS was <1, ranging from 0.18 to 0.45, indicating that the extraction performance of the commercial PDMS stir bar was better than that of the IL-[TESBPIM][NTf₂] stir bar for the considered compounds. These results were consistent with the difference in film thickness, 355 µm and 430 µm for the IL-[TESBPIM][NTf₂] stir bar and the PDMS stir bar, respectively. However, for some compounds, such as coumarin (log K₀/w = 1.39) and 2,2',4,5,5'-pentachlorobiphenyl (log K₀/w = 7.21), the area ratio was close to 1, indicating that the extraction performances of the two stir bars were comparable despite the difference in film thickness. After NaCl addition, a complete change in tendency was observed. A significant improvement was obtained in the extraction yields for all the compounds with a ratio of peak area-IL+NaCl/peak area PDMS+NaCl exceeding 1, especially with 2-butylthiophene (log K₀/w = 3.77) and 2,2',4,5,5'-pentachlorobiphenyl, where the ratios were greater than 200. The addition of NaCl could lead to an exchange of the counterion, resulting in a new ionic liquid, [TESBPIM] [Cl], with different properties. These results were strongly confirmed by the peak areas, which substantially increased for compounds extracted with the IL-stir bar but decreased considerably (>100-fold) for compounds extracted with the commercial PDMS stir bar. For 2,2',3,4,5,5'-hexachlorobiphenyl (log K₀/w = 6.70) and 9-nitroanthracene (log K₀/w = 4.78), the ratio could not be determined, as both compounds were not recovered using the
<figure><img src="image_9.png" /><figcaption>**Fig. 6.** Venn diagram of the compounds extracted from the Robec River water using the IL-stir bar with NaCl addition and a commercial PDMS stir bar with and without NaCl addition.</figcaption></figure>

commercial PDMS stir bar but only with the prepared IL-stir bar. As previously described in the literature, the addition of salt strongly decreases the extraction yields of apolar compounds when PDMS stir bars are used [24]. These results are particularly promising for pollutant analysis in brackish water or seawater. Also, ILs possess an interesting property which is called a 'dual nature behavior'. As ionic liquids are capable of solvating a large range of both polar and nonpolar molecules, they are capable of separating polar compounds as if they are polar stationary phases and nonpolar compounds as if they are nonpolar stationary phases [45]. Moreover, no coating degradation and non-significant changes in extraction yields were observed after 20 extractions and 6 months of use.

### 3.3. Extraction and analysis of emerging and/or persistent pollutants from natural freshwater

To test the performance of the prepared IL-stir bar, SBSE was performed on natural freshwater samples obtained from the Robec River (France) to determine emerging and persistent pollutants via non-targeted screening using GC-Orbitrap-HRMS instrument in full-scan

mode.

After extraction and analysis, the compounds were identified by using Compound Discoverer software. This software allows to isolate compounds from background noise and separates coelutions via a defined workflow. The obtained mass spectra were compared with those of the NIST and GC-HRMS libraries, and different scores were calculated, such as RSI (reverse search index), ΔRI (difference in retention indices) and RHRMF (reverse high-resolution mass filter). A scale of identification confidence proposed by G. Miller et al. [40]. was used to annotate the different compounds on the basis of the scores calculated via Compound Discoverer software. Five levels of confidence in compound annotation are defined: **level 5**: unknown feature; **level 4**: possible chemical class or series; **level 3**: tentative candidate (RSI>600 and RHRMF>75 %); **level 2**: probable structure or closer isomer (RSI>600, RHRMF>75 % and ΔRI<50 and 1.5 %); and **level 1**: confirmed identification (RT, EI spectra using an in-house library). In our study, only level 2 and 3 annotated compounds were selected because no standards were injected.

A data table combining all the detected compounds with all the attributed scores was obtained. Overall, after filtering all the silylated compounds generated by the column and the stir bar bleedings from a blank analysis, 1040 compounds were extracted from the chromatograms using the PDMS and the IL-stir bars. The number of detected peaks extracted using the IL-stir bar with added salt was comparable to those obtained with a PDMS stir bar with and without added NaCl. The results are represented as a Venn diagram in Fig. 6.

It can be noticed that the number of extracted compounds with the IL-stir bar with NaCl addition was greater than the number of detected compounds extracted by the commercial PDMS stir bar with or without NaCl addition to the same freshwater sample. Therefore, 832 compounds were extracted using the IL-stir bar, 760 using the PDMS stir bar without salt and 765 using the PDMS stir bar with NaCl addition. A total of 488 compounds, which represent half of the detected compounds, were detected using the three experiments (IL-stir bar + NaCl, PDMS stir bar and PDMS stir bar + NaCl). In terms of specificity, 167 compounds were extracted with only the IL-stir bar, 29 compounds were extracted with only the PDMS stir bar, and 15 were extracted with only the PDMS stir bar supplemented with NaCl. Moreover, 98 were extracted in common using an IL-stir bar and a PDMS stir bar with NaCl addition, and 79 were extracted in common with a PDMS stir bar without NaCl addition. Overall, the PDMS stir bar with added salt extracted slightly more compounds than the PDMS stir bar without added NaCl. This result could be related to a polar molecule profile since salt addition increased

<figure><img src="image_10.png" /><figcaption>**Fig. 7.** Number of compounds extracted as a function of the area ratios obtained between the peak area of IL+NaCl/peak area of PDMS and the peak area of IL+NaCl/peak area of PDMS+NaCl.</figcaption></figure>
<table><caption>**Table 2**

List of compounds detected in the Robec River water samples annotated as levels 2 and 3 via scores attributed by Compound Discoverer software.</caption><thead><tr><th>Compounds</th><th>Log K<sub>o/w</sub></th><th>T<sub>R</sub> (min)</th><th>Reference m/z</th><th>NIST Lib Hit Formula</th><th>RHRF</th><th>SI</th><th>RSI</th><th>ΔRI</th><th>% ΔRI</th><th>Level</th></tr></thead><tbody><tr><td>1H-Pyrrole, 2-ethyl-</td><td>1.58</td><td>8.04</td><td>96.07626</td><td>C<sub>6</sub>H<sub>9</sub>N</td><td>99.5</td><td>754</td><td>791</td><td>4</td><td>0.4</td><td>2</td></tr><tr><td>Dimethyl trisulfide</td><td>1.94</td><td>8.44</td><td>125.96265</td><td>C<sub>2</sub>H<sub>6</sub>S<sub>3</sub></td><td>91.2</td><td>713</td><td>748</td><td>4</td><td>0.4</td><td>2</td></tr><tr><td>Benzo[b]thiophene</td><td>2.90</td><td>12.06</td><td>134.01843</td><td>C<sub>8</sub>H<sub>6</sub>S</td><td>100.0</td><td>539</td><td>956</td><td>4</td><td>0.3</td><td>2</td></tr><tr><td>Propylbenzene</td><td>3.69</td><td>8.13</td><td>120.09343</td><td>C<sub>9</sub>H<sub>12</sub></td><td>91.5</td><td>554</td><td>786</td><td>5</td><td>0.5</td><td>2</td></tr><tr><td>Dimethyl sulfone</td><td>-1.41</td><td>7.59</td><td>95.01156</td><td>C<sub>2</sub>H<sub>6</sub>O<sub>2</sub>S</td><td>98.6</td><td>827</td><td>838</td><td>7</td><td>0.8</td><td>2*</td></tr><tr><td>Diethyl phthalate</td><td>2.47</td><td>17.30</td><td>149.02328</td><td>C<sub>12</sub>H<sub>14</sub>O<sub>4</sub></td><td>87.5</td><td>590</td><td>677</td><td>11</td><td>0.7</td><td>2</td></tr><tr><td>2-Ethylhexyl trans-4-methoxycinnamate</td><td>5.80</td><td>24.58</td><td>161.05962</td><td>C<sub>18</sub>H<sub>26</sub>O<sub>3</sub></td><td>94.3</td><td>607</td><td>757</td><td>13</td><td>0.6</td><td>2</td></tr><tr><td>2-Cyclopenten-1-one 2,3,4-trimethyl-</td><td>/</td><td>9.82</td><td>125.09177</td><td>C<sub>8</sub>H<sub>12</sub>O</td><td>100.0</td><td>891</td><td>935</td><td>15</td><td>1.4</td><td>2</td></tr><tr><td>2(5H)-Furanone, 5-(1-methylethyl)-</td><td>/</td><td>13.98</td><td>84.02065</td><td>C<sub>7</sub>H<sub>10</sub>O<sub>2</sub></td><td>100.0</td><td>641</td><td>787</td><td>15</td><td>1.1</td><td>2</td></tr><tr><td>1,1'-Biphenyl, 2,2',3,4,5-pentachloro-</td><td>6.62</td><td>22.89</td><td>122.01508</td><td>C<sub>12</sub>H<sub>5</sub>Cl<sub>5</sub></td><td>84.1</td><td>794</td><td>822</td><td>16</td><td>0.7</td><td>2</td></tr><tr><td>Carbazole</td><td>3.72</td><td>20.25</td><td>166.065</td><td>C<sub>12</sub>H<sub>9</sub>N</td><td>93.4</td><td>894</td><td>913</td><td>17</td><td>0.9</td><td>2</td></tr><tr><td>4-Ethyl-2-methoxy phenol</td><td>1.96</td><td>13.08</td><td>150.06755</td><td>C<sub>9</sub>H<sub>12</sub>O<sub>2</sub></td><td>100.0</td><td>537</td><td>771</td><td>19</td><td>1.5</td><td>2</td></tr><tr><td>Butanoic acid, 2-propenyl ester</td><td>1.51</td><td>6.70</td><td>101.02342</td><td>C<sub>7</sub>H<sub>12</sub>O<sub>2</sub></td><td>100.0</td><td>584</td><td>839</td><td>19</td><td>2.2</td><td>3*</td></tr><tr><td>2-Pyridinamine, 6-methyl-</td><td>0.97</td><td>9.80</td><td>108.0683</td><td>C<sub>6</sub>H<sub>8</sub>N<sub>2</sub></td><td>99.0</td><td>781</td><td>781</td><td>20</td><td>1.9</td><td>3</td></tr><tr><td>Maltol</td><td>0.65</td><td>11.11</td><td>126.03121</td><td>C<sub>6</sub>H<sub>6</sub>O<sub>3</sub></td><td>93.7</td><td>920</td><td>933</td><td>27</td><td>2.4</td><td>3</td></tr><tr><td>1,1'-Biphenyl, 2,2',3,4,4',5'-hexachloro-</td><td>7.27</td><td>24.98</td><td>122.01508</td><td>C<sub>12</sub>H<sub>4</sub>Cl<sub>6</sub></td><td>82.1</td><td>747</td><td>778</td><td>28</td><td>1.2</td><td>2*</td></tr><tr><td>Dimethyl sulfoxide</td><td>-1.35</td><td>6.64</td><td>62.98973</td><td>C<sub>2</sub>H<sub>6</sub>O S</td><td>100.0</td><td>915</td><td>976</td><td>36</td><td>4.6</td><td>3</td></tr><tr><td>Isothiazole, 4,5-dimethyl-</td><td>1.76</td><td>7.96</td><td>112.02165</td><td>C<sub>5</sub>H<sub>7</sub>N S</td><td>100.0</td><td>728</td><td>751</td><td>36</td><td>3.8</td><td>3*</td></tr><tr><td>1H-Pyrrole, 2,3,5-trimethyl-</td><td>1.46</td><td>8.30</td><td>109.0886</td><td>C<sub>7</sub>H<sub>11</sub>N</td><td>95.6</td><td>647</td><td>707</td><td>37</td><td>3.9</td><td>3</td></tr><tr><td>3-Methoxyacetophenone</td><td>1.89</td><td>14.31</td><td>136.04779</td><td>C<sub>9</sub>H<sub>10</sub>O<sub>2</sub></td><td>79.2</td><td>655</td><td>737</td><td>50</td><td>3.7</td><td>3</td></tr><tr><td>Benzofuran, 2-methyl-</td><td>2.74</td><td>11.59</td><td>152.15582</td><td>C<sub>9</sub>H<sub>8</sub>O</td><td>81.7</td><td>539</td><td>737</td><td>56</td><td>4.8</td><td>3</td></tr><tr><td>1,4-Cyclohex-2-edenedione</td><td>/</td><td>8.56</td><td>110.03632</td><td>C<sub>6</sub>H<sub>6</sub>O<sub>2</sub></td><td>92.1</td><td>739</td><td>759</td><td>59</td><td>6.1</td><td>3</td></tr><tr><td>Levomenthol</td><td>2.40</td><td>13.14</td><td>399.00555</td><td>C<sub>10</sub>H<sub>20</sub>O</td><td>100.0</td><td>564</td><td>853</td><td>92</td><td>7.3</td><td>3</td></tr><tr><td>o-Methoxybenzoic acid, 2-chlorophenyl ester</td><td>3.56</td><td>21.89</td><td>64.99672</td><td>C<sub>14</sub>H<sub>11</sub>Cl O<sub>3</sub></td><td>93.0</td><td>721</td><td>911</td><td>92</td><td>4.5</td><td>3</td></tr><tr><td>Pyridine, 4-methyl-</td><td>1.39</td><td>8.49</td><td>89.04176</td><td>C<sub>6</sub>H<sub>7</sub>N</td><td>76.1</td><td>582</td><td>855</td><td>106</td><td>10.9</td><td>3</td></tr><tr><td>2(3H)-Furanone, dihydro-5-propyl-</td><td>1.49</td><td>13.13</td><td>110.07262</td><td>C<sub>7</sub>H<sub>12</sub>O<sub>2</sub></td><td>78.5</td><td>634</td><td>779</td><td>107</td><td>8.5</td><td>3</td></tr><tr><td>Phenol</td><td>1.46</td><td>10.73</td><td>67.04978</td><td>C<sub>6</sub>H<sub>6</sub>O</td><td>99.7</td><td>937</td><td>979</td><td>140</td><td>12.6</td><td>3</td></tr><tr><td>Furan 2-ethyl-5-methyl-</td><td>2.15</td><td>8.74</td><td>110.07263</td><td>C<sub>7</sub>H<sub>10</sub>O</td><td>97.1</td><td>854</td><td>902</td><td>182</td><td>18.5</td><td>3</td></tr><tr><td>[1,1'-Biphenyl] -4-amine</td><td>2.93</td><td>16.65</td><td>167.0728</td><td>C<sub>12</sub>H<sub>11</sub>N</td><td>87.4</td><td>655</td><td>705</td><td>230</td><td>15.1</td><td>3</td></tr><tr><td>Mandelamide</td><td>1.25</td><td>12.26</td><td>71.07297</td><td>C<sub>8</sub>H<sub>9</sub>N O<sub>2</sub></td><td>100.0</td><td>664</td><td>808</td><td>332</td><td>27.6</td><td>3</td></tr><tr><td>1-Octene, 7-methyl-</td><td>3.38</td><td>12.45</td><td>70.06071</td><td>C<sub>9</sub>H<sub>18</sub></td><td>100.0</td><td>661</td><td>875</td><td>488</td><td>38.8</td><td>3</td></tr><tr><td>Pyridine</td><td>0.65</td><td>13.01</td><td>159.08047</td><td>C<sub>5</sub>H<sub>5</sub>N</td><td>100.0</td><td>661</td><td>772</td><td>1120</td><td>119.8</td><td>3</td></tr><tr><td>dl-Menthol</td><td>3.20</td><td>20.68</td><td>94.04134</td><td>C<sub>10</sub>H<sub>20</sub>O</td><td>99.4</td><td>744</td><td>806</td><td>733</td><td>38.4</td><td>3</td></tr><tr><td>cis-3-Hexenyl cis-3-hexenoate</td><td>/</td><td>24.28</td><td>83.0729</td><td>C<sub>12</sub>H<sub>20</sub>O<sub>2</sub></td><td>92.2</td><td>685</td><td>734</td><td>903</td><td>39.4</td><td>3</td></tr><tr><td>Mepivacaine</td><td>2.72</td><td>7.91</td><td>165.03989</td><td>C<sub>15</sub>H<sub>22</sub>N<sub>2</sub>O</td><td>95.4</td><td>521</td><td>772</td><td>1120</td><td>119.8</td><td>3</td></tr><tr><td>1-Nonene</td><td>3.35</td><td>24.17</td><td>131.05234</td><td>C<sub>9</sub>H<sub>18</sub></td><td>100.0</td><td>659</td><td>747</td><td>1390</td><td>61</td><td>3</td></tr><tr><td>2-Propanone, 1-chloro-</td><td>0.81</td><td>24.09</td><td>93.9994</td><td>C<sub>3</sub>H<sub>5</sub>Cl O</td><td>100.0</td><td>631</td><td>943</td><td>1587</td><td>69.9</td><td>3</td></tr><tr><td>1-Naphthalenemethyl naphthalene-2-carboxylate</td><td>/</td><td>3.04</td><td>141.06992</td><td>C<sub>22</sub>H<sub>16</sub>O<sub>2</sub></td><td>100.0</td><td>628</td><td>658</td><td>/</td><td>/</td><td>3</td></tr><tr><td>Diamide</td><td>/</td><td>3.08</td><td>197.13242</td><td>C<sub>6</sub>H<sub>12</sub>N<sub>4</sub>O<sub>2</sub></td><td>90.0</td><td>879</td><td>937</td><td>/</td><td>/</td><td>3</td></tr><tr><td>3-Buten-1-amine, N,N-dimethyl-</td><td>/</td><td>3.71</td><td>58.06521</td><td>C<sub>6</sub>H<sub>13</sub>N</td><td>97.1</td><td>932</td><td>948</td><td>/</td><td>/</td><td>3</td></tr><tr><td>Butane, 1-isocyanato-</td><td>1.12</td><td>4.96</td><td>98.06005</td><td>C<sub>5</sub>H<sub>9</sub>N O</td><td>100.0</td><td>566</td><td>734</td><td>/</td><td>/</td><td>3</td></tr><tr><td>2-Propanol, 1-methoxy-2-methyl-</td><td>0.49</td><td>6.30</td><td>59.04918</td><td>C<sub>5</sub>H<sub>12</sub>O<sub>2</sub></td><td>100.0</td><td>858</td><td>917</td><td>/</td><td>/</td><td>3*</td></tr><tr><td>2-Propanone, oxime</td><td>0.85</td><td>6.33</td><td>73.05225</td><td>C<sub>3</sub>H<sub>7</sub>N O</td><td>100.0</td><td>646</td><td>957</td><td>/</td><td>/</td><td>3</td></tr><tr><td>2-Ethylpiperidine</td><td>1.53</td><td>6.44</td><td>85.08413</td><td>C<sub>7</sub>H<sub>15</sub>N</td><td>99.5</td><td>775</td><td>792</td><td>/</td><td>/</td><td>3*</td></tr><tr><td>Acetamide, N-butyl-2,2,2-trifluoro-</td><td>1.46</td><td>7.15</td><td>100.07571</td><td>C<sub>6</sub>H<sub>10</sub>F<sub>3</sub>N O</td><td>99.4</td><td>807</td><td>814</td><td>/</td><td>/</td><td>3</td></tr><tr><td>1H-Imidazole, 1-methyl-</td><td>/</td><td>7.61</td><td>83.06015</td><td>C<sub>4</sub>H<sub>6</sub>N<sub>2</sub></td><td>98.4</td><td>910</td><td>910</td><td>/</td><td>/</td><td>3</td></tr><tr><td>Benzenamine, 4-(octyloxy)-</td><td>4.00</td><td>7.64</td><td>108.081</td><td>C<sub>14</sub>H<sub>23</sub>N O</td><td>100.0</td><td>734</td><td>777</td><td>/</td><td>/</td><td>3</td></tr><tr><td>1H-Imidazole-4-ethanamine, N-methyl-</td><td>/</td><td>7.71</td><td>52.01825</td><td>C<sub>6</sub>H<sub>11</sub>N<sub>3</sub></td><td>99.0</td><td>738</td><td>738</td><td>/</td><td>/</td><td>3</td></tr><tr><td>3-Cyano-3-octyl-1,4-cyclohexadiene</td><td>/</td><td>8.36</td><td>105.0573</td><td>C<sub>15</sub>H<sub>23</sub>N</td><td>100.0</td><td>743</td><td>908</td><td>/</td><td>/</td><td>3</td></tr><tr><td>Piperidine, 1-butyl-</td><td>2.27</td><td>8.42</td><td>98.09644</td><td>C<sub>9</sub>H<sub>19</sub>N</td><td>78.7</td><td>691</td><td>691</td><td>/</td><td>/</td><td>3</td></tr><tr><td>1,4-Dioxane, 2,3-dimethoxy-</td><td>/</td><td>8.78</td><td>117.09102</td><td>C<sub>6</sub>H<sub>12</sub>O<sub>4</sub></td><td>96.1</td><td>733</td><td>805</td><td>/</td><td>/</td><td>3*</td></tr><tr><td>Diamidafos</td><td>/</td><td>8.94</td><td>106.02874</td><td>C<sub>8</sub>H<sub>13</sub>N<sub>2</sub>O<sub>2</sub>P</td><td>100.0</td><td>629</td><td>664</td><td>/</td><td>/</td><td>3</td></tr><tr><td>1,1'-Bicyclohexyl-1,1'-diol</td><td>/</td><td>9.76</td><td>98.10902</td><td>C<sub>12</sub>H<sub>22</sub>O<sub>2</sub></td><td>81.7</td><td>753</td><td>841</td><td>/</td><td>/</td><td>3</td></tr><tr><td>Dihydroxyphenylalanine</td><td>0.05</td><td>10.76</td><td>124.01559</td><td>C<sub>9</sub>H<sub>11</sub>N O<sub>4</sub></td><td>100.0</td><td>608</td><td>739</td><td>/</td><td>/</td><td>3</td></tr><tr><td>1-Propanamine, N-(2-furanylmethylene)-2-methyl-</td><td>/</td><td>11.57</td><td>122.06019</td><td>C<sub>9</sub>H<sub>13</sub>N O</td><td>99.5</td><td>685</td><td>690</td><td>/</td><td>/</td><td>3</td></tr><tr><td>Tetrahydropyrrolo[2,1-c][1,4]oxazin-4-one</td><td>/</td><td>11.83</td><td>111.03149</td><td>C<sub>7</sub>H<sub>11</sub>N O<sub>2</sub></td><td>76.9</td><td>647</td><td>885</td><td>/</td><td>/</td><td>3</td></tr><tr><td>Isoetharine</td><td>2.20</td><td>11.90</td><td>85.06493</td><td>C<sub>13</sub>H<sub>21</sub>N O<sub>3</sub></td><td>100.0</td><td>549</td><td>872</td><td>/</td><td>/</td><td>3</td></tr><tr><td>2-Pyrazoline, 1-isobutyl-3-methyl-</td><td>1.72</td><td>12.09</td><td>82.06513</td><td>C<sub>8</sub>H<sub>16</sub>N<sub>2</sub></td><td>100.0</td><td>652</td><td>659</td><td>/</td><td>/</td><td>3</td></tr><tr><td>Butyramide, 2-cyano-2-ethyl-</td><td>/</td><td>12.22</td><td>55.04175</td><td>C<sub>7</sub>H<sub>12</sub>N<sub>2</sub>O</td><td>96.9</td><td>708</td><td>717</td><td>/</td><td>/</td><td>3</td></tr><tr><td>MDPBP</td><td>/</td><td>12.70</td><td>148.07555</td><td>C<sub>15</sub>H<sub>19</sub>N O<sub>3</sub></td><td>100.0</td><td>593</td><td>751</td><td>/</td><td>/</td><td>3*</td></tr><tr><td>1,5-Dimethylbarbituric acid</td><td>-0.66</td><td>12.72</td><td>58.02883</td><td>C<sub>6</sub>H<sub>8</sub>N<sub>2</sub>O<sub>3</sub></td><td>100.0</td><td>529</td><td>873</td><td>/</td><td>/</td><td>3</td></tr><tr><td>Benzene, 1-chloro-4-(1-propynyl)-</td><td>/</td><td>12.83</td><td>150.02307</td><td>C<sub>9</sub>H<sub>7</sub>Cl</td><td>100.0</td><td>719</td><td>744</td><td>/</td><td>/</td><td>3</td></tr><tr><td>1-Chloromethyl-4-(1,1-dimethylethoxy)benzene</td><td>/</td><td>12.96</td><td>98.99961</td><td>C<sub>11</sub>H<sub>15</sub>Cl O</td><td>100.0</td><td>756</td><td>828</td><td>/</td><td>/</td><td>3</td></tr><tr><td>3-Buten-2-one, 4-(1-aziridinyl)-</td><td>/</td><td>13.04</td><td>111.06784</td><td>C<sub>6</sub>H<sub>9</sub>N O</td><td>100.0</td><td>653</td><td>831</td><td>/</td><td>/</td><td>3</td></tr></tbody></table>

(continued on next page)
<table><caption>**Table 2 (continued)**</caption><thead><tr><th>Compounds</th><th>Log K<sub>o/w</sub></th><th>T<sub>R</sub> (min)</th><th>Reference m/z</th><th>NIST Lib Hit Formula</th><th>RHRF</th><th>SI</th><th>RSI</th><th>ΔRI</th><th>% ΔRI</th><th>Level</th></tr></thead><tbody><tr><td>Bupivacaine</td><td>4.54</td><td>13.32</td><td>146.10887</td><td>C<sub>18</sub>H<sub>28</sub>N<sub>2</sub>O</td><td>93.9</td><td>760</td><td>882</td><td>/</td><td>/</td><td>3</td></tr><tr><td>2-Propenoic acid, 2-methyl-, 2-propenyl ester</td><td>/</td><td>13.47</td><td>97.06486</td><td>C<sub>7</sub>H<sub>10</sub>O<sub>2</sub></td><td>100.0</td><td>857</td><td>857</td><td>/</td><td>/</td><td>3*</td></tr><tr><td>1H-Pyrrolo[2,3-b]pyridine, 2-methyl-</td><td>/</td><td>13.98</td><td>132.06812</td><td>C<sub>8</sub>H<sub>8</sub>N<sub>2</sub></td><td>99.3</td><td>830</td><td>851</td><td>/</td><td>/</td><td>3</td></tr><tr><td>7-Methyl-1,2-dihydroquinoxalin-2-one</td><td>/</td><td>14.17</td><td>132.05702</td><td>C<sub>9</sub>H<sub>8</sub>N<sub>2</sub>O</td><td>100.0</td><td>515</td><td>707</td><td>/</td><td>/</td><td>3</td></tr><tr><td>N-Methoxy-N-methylbenzamide</td><td>/</td><td>14.27</td><td>133.02831</td><td>C<sub>9</sub>H<sub>11</sub>N O<sub>2</sub></td><td>97.2</td><td>679</td><td>836</td><td>/</td><td>/</td><td>3</td></tr><tr><td>2-Methyl-3-nitrophenyl β-phenylpropionate</td><td>/</td><td>14.46</td><td>125.04715</td><td>C<sub>16</sub>H<sub>15</sub>N O<sub>4</sub></td><td>100.0</td><td>692</td><td>928</td><td>/</td><td>/</td><td>3</td></tr><tr><td>Acetamide, N-(5-ethoxy-2-pyrimidinyl)-</td><td>/</td><td>15.72</td><td>111.0679</td><td>C<sub>8</sub>H<sub>11</sub>N<sub>3</sub>O<sub>2</sub></td><td>90.9</td><td>520</td><td>683</td><td>/</td><td>/</td><td>3</td></tr><tr><td>Benzenemethanamine, N,N-dimethyl-α-(dimethylamino)-</td><td>/</td><td>16.25</td><td>134.09656</td><td>C<sub>11</sub>H<sub>18</sub>N<sub>2</sub></td><td>95.8</td><td>690</td><td>930</td><td>/</td><td>/</td><td>3*</td></tr><tr><td>5-[1(R,S),2-Dihydroxyethyl]tetrazole</td><td>/</td><td>16.71</td><td>98.98415</td><td>C<sub>3</sub>H<sub>6</sub>N<sub>4</sub>O<sub>2</sub></td><td>97.1</td><td>806</td><td>967</td><td>/</td><td>/</td><td>3</td></tr><tr><td>1H-Pyrrolo[2,3-b]pyridine, 2-ethyl-</td><td>/</td><td>16.91</td><td>188.15569</td><td>C<sub>9</sub>H<sub>10</sub>N<sub>2</sub></td><td>100.0</td><td>808</td><td>895</td><td>/</td><td>/</td><td>3</td></tr><tr><td>Phenyl 4-(chloromethyl)benzoate</td><td>/</td><td>17.41</td><td>153.01004</td><td>C<sub>14</sub>H<sub>11</sub>Cl O<sub>2</sub></td><td>100.0</td><td>741</td><td>811</td><td>/</td><td>/</td><td>3</td></tr><tr><td>Acetamide, N,N-dipentyl-</td><td>/</td><td>17.85</td><td>59.0366</td><td>C<sub>12</sub>H<sub>25</sub>N O</td><td>100.0</td><td>604</td><td>701</td><td>/</td><td>/</td><td>3</td></tr><tr><td>Pyrazine, methoxy-, 4-oxide</td><td>/</td><td>18.48</td><td>145.02837</td><td>C<sub>5</sub>H<sub>6</sub>N<sub>2</sub>O<sub>2</sub></td><td>94.8</td><td>585</td><td>674</td><td>/</td><td>/</td><td>3</td></tr><tr><td>4-Butylbenzoic acid, 4-chloro-2-methylphenyl ester</td><td>/</td><td>18.89</td><td>162.11661</td><td>C<sub>18</sub>H<sub>19</sub>Cl O<sub>2</sub></td><td>97.9</td><td>724</td><td>732</td><td>/</td><td>/</td><td>3</td></tr><tr><td>2-Methylbenzoic acid, 4-isopropylphenyl ester</td><td>/</td><td>19.27</td><td>120.05253</td><td>C<sub>17</sub>H<sub>18</sub>O<sub>2</sub></td><td>96.8</td><td>599</td><td>832</td><td>/</td><td>/</td><td>3</td></tr><tr><td>5,6,7,8-Tetrahydroindolizine</td><td>/</td><td>19.56</td><td>120.08092</td><td>C<sub>8</sub>H<sub>11</sub>N</td><td>97.6</td><td>756</td><td>756</td><td>/</td><td>/</td><td>3</td></tr><tr><td>1,2,3,4,5,6-Hexahydro-1-[2-mercaptoethyl]-S-triazine-2.4.6-trione</td><td>/</td><td>19.98</td><td>87.01855</td><td>C<sub>5</sub>H<sub>7</sub>N<sub>3</sub>O<sub>3</sub>S</td><td>82.4</td><td>505</td><td>725</td><td>/</td><td>/</td><td>3</td></tr><tr><td>2-Chloroethyl carbonate</td><td>1.61</td><td>21.79</td><td>64.99666</td><td>C<sub>5</sub>H<sub>8</sub>Cl<sub>2</sub>O<sub>3</sub></td><td>100.0</td><td>661</td><td>866</td><td>/</td><td>/</td><td>3</td></tr><tr><td>1,3-Dimethyl-2,4(1H,3H)-quinazolinedione</td><td>/</td><td>21.88</td><td>190.07346</td><td>C<sub>10</sub>H<sub>10</sub>N<sub>2</sub>O<sub>2</sub></td><td>88.8</td><td>538</td><td>684</td><td>/</td><td>/</td><td>3</td></tr><tr><td>(1R,2S)-(-)-2-Amino-1,2-diphenylethanol</td><td>/</td><td>22.03</td><td>106.06509</td><td>C<sub>14</sub>H<sub>15</sub>N O</td><td>100.0</td><td>750</td><td>983</td><td>/</td><td>/</td><td>3</td></tr><tr><td>Benzocyclobuten-1(2H)-one</td><td>1.42</td><td>22.42</td><td>90.04642</td><td>C<sub>8</sub>H<sub>6</sub>O</td><td>100.0</td><td>740</td><td>984</td><td>/</td><td>/</td><td>3</td></tr><tr><td>Acetanilide, N-(1-(dimethylcarbamoyl)ethyl)-</td><td>/</td><td>22.54</td><td>148.03926</td><td>C<sub>13</sub>H<sub>18</sub>N<sub>2</sub>O<sub>2</sub></td><td>100.0</td><td>740</td><td>815</td><td>/</td><td>/</td><td>3*</td></tr><tr><td>Benzeneethanamine, 4-amino-N-methyl-N-(2-phenylethyl)-</td><td>/</td><td>22.73</td><td>183.09154</td><td>C<sub>17</sub>H<sub>22</sub>N<sub>2</sub></td><td>100.0</td><td>582</td><td>762</td><td>/</td><td>/</td><td>3</td></tr><tr><td>2-Amino-4-morpholino-6-morpholinomethyl-1,3,5-triazine</td><td>/</td><td>23.11</td><td>195.14906</td><td>C<sub>12</sub>H<sub>20</sub>N<sub>6</sub>O<sub>2</sub></td><td>100.0</td><td>624</td><td>688</td><td>/</td><td>/</td><td>3*</td></tr><tr><td>1,2,4-Oxadiazol-5-amine, 3-(4-amino-1,2,5-oxadiazol-3-yl)-N-[2-(4-methoxyphenyl)ethyl]-</td><td>/</td><td>23.24</td><td>120.05253</td><td>C<sub>13</sub>H<sub>14</sub>N<sub>6</sub>O<sub>3</sub></td><td>100.0</td><td>706</td><td>816</td><td>/</td><td>/</td><td>3*</td></tr><tr><td>Benzoic acid 1,1-dimethylethyl ester</td><td>2.64</td><td>23.58</td><td>105.03353</td><td>C<sub>11</sub>H<sub>14</sub>O<sub>2</sub></td><td>96.4</td><td>875</td><td>875</td><td>/</td><td>/</td><td>3</td></tr><tr><td>Ethyl 9-fluorenylideneacetate</td><td>/</td><td>24.15</td><td>205.06459</td><td>C<sub>17</sub>H<sub>14</sub>O<sub>2</sub></td><td>94.4</td><td>706</td><td>716</td><td>/</td><td>/</td><td>3</td></tr><tr><td>Phenanthrene</td><td>4.46</td><td>24.46</td><td>178.0775</td><td>C<sub>14</sub>H<sub>10</sub></td><td>100.0</td><td>700</td><td>812</td><td>/</td><td>/</td><td>3*</td></tr><tr><td>Sydnone, 3-neopentyl-</td><td>/</td><td>25.02</td><td>210.13568</td><td>C<sub>7</sub>H<sub>12</sub>N<sub>2</sub>O<sub>2</sub></td><td>100.0</td><td>606</td><td>796</td><td>/</td><td>/</td><td>3</td></tr><tr><td>9,10-Anthracenedicarboxaldehyde</td><td>/</td><td>25.48</td><td>205.06459</td><td>C<sub>16</sub>H<sub>10</sub>O<sub>2</sub></td><td>96.4</td><td>564</td><td>773</td><td>/</td><td>/</td><td>3</td></tr><tr><td>Anthracene, 9,10-diethyl-9,10-dihydro-</td><td>5.08</td><td>26.55</td><td>207.11668</td><td>C<sub>18</sub>H<sub>20</sub></td><td>100.0</td><td>698</td><td>728</td><td>/</td><td>/</td><td>3</td></tr><tr><td>3-Butanol, 1-benzyloxy-2-methyl-</td><td>/</td><td>26.68</td><td>92.06211</td><td>C<sub>12</sub>H<sub>18</sub>O<sub>2</sub></td><td>100.0</td><td>761</td><td>789</td><td>/</td><td>/</td><td>3</td></tr><tr><td>1,3-Benzenedicarboxylic acid, bis(2-ethylhexyl) ester</td><td>6.43</td><td>27.88</td><td>167.03391</td><td>C<sub>24</sub>H<sub>38</sub>O<sub>4</sub></td><td>89.7</td><td>742</td><td>757</td><td>/</td><td>/</td><td>3</td></tr><tr><td>Decanenitrile</td><td>3.65</td><td>29.20</td><td>71.07294</td><td>C<sub>10</sub>H<sub>19</sub>N</td><td>100.0</td><td>665</td><td>691</td><td>/</td><td>/</td><td>3</td></tr><tr><td>1-Phenyl-1-heptyne</td><td>3.61</td><td>29.71</td><td>128.06207</td><td>C<sub>13</sub>H<sub>16</sub></td><td>100.0</td><td>654</td><td>726</td><td>/</td><td>/</td><td>3*</td></tr><tr><td>Vitamin E</td><td>8.84</td><td>30.59</td><td>136.08833</td><td>C<sub>29</sub>H<sub>50</sub>O<sub>2</sub></td><td>100.0</td><td>885</td><td>885</td><td>/</td><td>/</td><td>3</td></tr></tbody></table>

the extraction yields only for polar compounds when the PDMS stir bars were used. This diagram shows that the prepared IL-stir bar has a good ability to extract organic compounds from water with added salt. Moreover, despite having a lower thickness than the commercial PDMS stir bar, this novel IL coating showed better performances and could extract 5 times more compounds than the commercial PDMS stir bar. These characteristics could be interesting advantages for the extraction of estuary water and seawater without supplementary sample preparation.

For most of the compounds coextracted with the PDMS stir bar (with or without added salt) and the IL-stir bar, the former with and without added salt obtained considerably smaller peak areas than did the latter. Fig. 7 shows the ratio between the peak areas of the compounds extracted using the IL-stir bar with added salt and the PDMS stir bar with and without added salt.

Fig. 7 shows that 155 and 164 compounds have ratios of peak area IL+NaCl/peak area PDMS and peak area IL+NaCl/peak area PDMS+NaCl, respectively, that are <1. In contrast, twice as many compounds have a ratio greater than or equal to 1. This finding indicates that the areas obtained for the compounds extracted with the IL-stir bar were significantly larger than those obtained using the PDMS stir bar, both with and without the addition of NaCl. However, for more than 300 compounds, the area ratio could not be calculated because the compounds were not

extracted by one of the stir bars.

Thus, extraction using the prepared IL-stir bar with NaCl addition significantly improved the extraction yields for more than half of the extracted compounds.

On the basis of the confidence scale, a list of filters was used to classify the 1040 detected compounds. All the compounds with an RSI< 600 and an RHRMF < 75 % were filtered out to keep only compounds annotated from levels 2 and 3. A total of 343 compounds were obtained, 330 of which were classified as level 3, and with the addition of the RI filter under 50 and < 1.5 %, 13 compounds were classified as level 2.

Table 2 summarizes the 343 nontarget compounds annotated with levels 2 and 3 in the Robec River water sample with the parameters used for their identification and classification. Fifteen of these identified compounds were exclusively extracted with the IL-stir bar and not with the commercial PDMS stir bar with or without NaCl addition. The compounds annotated at level 2 included compounds that were identified as molecules belonging to specific families of emerging and/or persisting pollutants. The list included two polychlorinated biphenyls (PCB 90: 2,2',3,4,5-pentachlorobiphenyl and PCB 138: 2,2',3',4,4',5-hexachlorobiphenyl), plasticizers (diethyl phthalate), food additives (maltol), personal care products (UV filter: 2-ethylhexyl trans-4-methoxycinnamate) and pesticides (4,5-dimethylisothiazole). For the compounds at level 3, tentative candidates included pharmaceuticals

<footnote>* Compounds extracted only with the prepared IL-stir bar, T<sub>R</sub>: Retention time, RHRF: Reverse High-Resolution Factor, SI: Search Index, RSI: Reverse Search Index, ΔRI: Retention Index variation.</footnote>
<figure><img src="image_11.png" /><figcaption>**Fig. 8.** Variation in the ratio of peak area$_{-IL+NaCl/peak area_{PDMS+NaCl}}$ of the level 2 and 3 detected compounds from Robec river as a function of compound polarity.</figcaption></figure>

(bupivacaine, MDPBP, [3',4'-methylenedioxy-α-pyrrolidinobutyronophenone], isoethylene and leishmaniasis), pesticides (diamidafos), PAHs (phenanthrene) and plasticizers (1,3-benzenedicarboxylic acid, bis(2-ethylhexyl) ester).

A representation of the ratio between the peak areas obtained with the IL-stir bar and the PDMS stir bar with NaCl addition as a function of the polarity of 54 detected compounds of identification level 2 and 3 from Robec river was established. The polarities are expressed as a function of log K$_{o/w}$ for each compound (represented in Table 2) and a logarithmic transformation was applied for the area ratios to reduce the disparity between values and improve visualization of the results. As shown in Fig. 8, for compounds with log K$_{o/w}$ < 4, the log ratio of peak areas of the compounds is greater than 1, showing that the extraction yields obtained with the IL-stir bar are for a large majority of compounds greater than those obtained with the PDMS stir bar. For the compounds with log K$_{o/w}$ > 4, the observed ratio equals 1 for most of the compounds showing the same extraction yields for these compounds with the IL-stir bar and the PDMS stir bar. This shows the enhance of the extraction yields hydrophilic compounds with a loss of performance for the hydrophobic ones. Moreover, phenanthrene (log K$_{o/w}$ 4.46) was only extracted using the IL-stir bar confirming the results observed with 9 nitroanthracene in Section 3.2.

## 4. Conclusion

In the present study, the development of a new ionic liquid-based coating for SBSE using the sol-gel method has led to significant improvements in the extraction and analysis of a wide range of pollutants. The [TESBPIM][Cl] ionic liquid allowed the best coating to offer a homogeneous, crack-free surface with high thermal stability. The extraction was highly enhanced by the addition of NaCl, particularly for compounds with log K$_{o/w}$ > 4, outperforming the commercial PDMS stir bar. This result could be due to structural modification of the IL through anion exchange, leading to an IL with different properties than the initial one. The application of the coated stir bar in a nontarget SBSE-TD-GC-Orbitrap-HRMS method successfully detected over 1072 compounds in the Robec River, including emerging and persistent pollutants such as PCBs, pesticides, personal care products and pharmaceuticals. The specific detection of >160 compounds and the increase in peak areas

highlight the potential of the new SBSE IL-stir bar coating for comprehensive environmental monitoring. The high extraction efficiency, particularly under saline conditions, makes this IL-coated stir bar a valuable tool for analyzing contaminants in complex aquatic environments, including estuary water or seawater.

## CRediT authorship contribution statement

**Amel Meziani:** Writing – original draft, Methodology, Formal analysis. **Ouassila Ferroukhi:** Writing – review & editing, Supervision, Funding acquisition. **Valerie Peulon-Agasse:** Writing – review & editing, Supervision, Methodology. **Pascal Cardinael:** Writing – review & editing, Supervision, Funding acquisition, Conceptualization.

## Declaration of competing interest

The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:

MEZIANI reports financial support was provided by PHC TASSILI. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

## Acknowledgments

A.M gratefully acknowledges the Partenariat Hubert Curien (PHC) Tassili for its financial support (PhD grant). The authors thanks Dr. Severine TISSE and Dr. Aurelien CURAT from SMS laboratory UR3 3233 for the synthesis of the ionic liquid derivative. The authors would like to thank Mr Trevys CHANAL for collecting water from the River Robec.

## Data availability

Data will be made available on request.

## References

[1] F. Wang, et al., Emerging contaminants: a one health perspective, Innovation 5 (4) (2024) 100612, https://doi.org/10.1016/j.xinn.2024.100612. Jul.
[2] C. Qi, J. Huang, B. Wang, S. Deng, Y. Wang, G. Yu, Contaminants of emerging concern in landfill leachate in China: a review, Emerg. Contam. 4 (1) (2018) 1–10, https://doi.org/10.1016/j.emcon.2018.06.001.

[3] G. Teijon, L. Candela, K. Tamoh, A. Molina-Díaz, A.R. Fernández-Alba, Occurrence of emerging contaminants, priority substances (2008/105/CE) and heavy metals in treated wastewater and groundwater at Depurbaix facility (Barcelona, Spain), Sci. Total Environ. 408 (17) (2010) 3584–3595, https://doi.org/10.1016/j.scitotenv.2010.04.041. Aug.

[4] M.S. Díaz-Cruz, D. Barceló, Trace organic chemicals contamination in ground water recharge, Chemosphere 72 (3) (2008) 333–342, https://doi.org/10.1016/j.chemosphere.2008.02.031. Jun.

[5] L. Wolf, M. Eiswirth, H. Hötzl, Assessing sewer–groundwater interaction at the city scale based on individual sewer defects and marker species distributions, Environ. Geol. 49 (6) (2006) 849–857, https://doi.org/10.1007/s00254-006-0180-x. Mar.

[6] S. Weiss, T. Reemtsma, Determination of benzotriazole corrosion inhibitors from aqueous environmental samples by liquid chromatography-electrospray ionization-tandem mass spectrometry, Anal. Chem. 77 (22) (2005) 7415–7420, https://doi.org/10.1021/ac051203e. Nov.

[7] M. Carballa, et al., Behaviour of pharmaceuticals and personal care products in a sewage treatment plant of northwest Spain, Water Sci. Technol. 52 (8) (2005) 29–35, https://doi.org/10.2166/wst.2005.0218. Oct.

[8] T. Reemtsma, U. Miehe, U. Duennbier, M. Jekel, Polar pollutants in municipal wastewater and the water cycle: occurrence and removal of benzotriazoles, Water Res. 44 (2) (2010) 596–604, https://doi.org/10.1016/j.watres.2009.07.016. Jan.

[9] V. Matamoros, E. Jover, J.M. Bayona, Part-per-trillion determination of pharmaceuticals, pesticides, and related organic contaminants in river water by solid-phase extraction followed by comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry, Anal. Chem. 82 (2) (2010) 699–706, https://doi.org/10.1021/ac902340e. Jan.

[10] F. Riva, E. Zuccato, E. Davoli, E. Fattore, S. Castiglioni, Risk assessment of a mixture of emerging contaminants in surface water in a highly urbanized area in Italy, J. Hazard. Mater. 361 (2019) 103–110, https://doi.org/10.1016/j.jhazmat.2018.07.099. Jan.

[11] J. Kapelewksa, U. Kotowska, J. Karpinska, D. Kowalczuk, A. Arciszewska, A. Swirydo, Occurrence, removal, mass loading and environmental risk assessment of emerging organic contaminants in leachates, groundwaters and wastewaters, Microchem. J. 137 (2018) 292–301, https://doi.org/10.1016/j.microc.2017.11.008. Mar.

[12] The European parliament and of the council, 'Directive 2000/60/EC, envirenmental quality standards for priority substances and certain other pollutants', http://data.europa.eu/eli/dir/2000/60/2014-11-20, (accessed: 12 July 2024).

[13] H. Janna, Occurrence and Removal of Emerging Contaminants in Wastewaters, PhD Thesis, Brunel University Institute for the Environment, London, 2011.

[14] L. Ramos, Critical overview of selected contemporary sample preparation techniques. J. Chromatogr. A 1221 (2012) 84–98, https://doi.org/10.1016/j.chromatogr.a.2011.11.011. Jan.

[15] A.N. Anthemidis, K.-I.G. Ioannou, On-line sequential injection dispersive liquid–liquid microextraction system for flame atomic absorption spectrometric determination of copper and lead in water samples, Talanta 79 (1) (2009) 86–91, https://doi.org/10.1016/j.talanta.2009.03.005. Jun.

[16] J. Regueiro, E. Becerril, C. Garcia-Jares, M. Llopart, Trace analysis of parabens, triclosan and related chlorophenols in water by headspace solid-phase microextraction with in situ derivatization and gas chromatography–tandem mass spectrometry, J. Chromatogr. A 1216 (23) (2009) 4693–4702, https://doi.org/10.1016/j.chroma.2009.04.025. Jun.

[17] M.M. Moein, A. Abdel-Rehim, M. Abdel-Rehim, Microextraction by packed sorbent (MEPS), TrAC Trends Anal. Chem. 67 (2015) 34–44, https://doi.org/10.1016/j.trac.2014.12.003. Apr.

[18] N. Ochiai, et al., Stir bar sorptive extraction and comprehensive two-dimensional gas chromatography coupled to high-resolution time-of-flight mass spectrometry for ultra-trace analysis of organochlorine pesticides in river water, J. Chromatogr. A 1218 (39) (2011) 6851–6860, https://doi.org/10.1016/j.chroma.2011.08.027. Sep.

[19] O. Canlı, K. Çetintürk, E.E. Öktem Olgun, Determination of 117 endocrine disruptors (EDCs) in water using SBSE TD-GC-MS/MS under the European Water Framework Directive, Anal. Bioanal. Chem. 412 (21) (2020) 5169–5178, https://doi.org/10.1007/s00216-020-02553-4. Aug.

[20] F. David, P. Sandra, Stir bar sorptive extraction for trace analysis, J. Chromatogr. A 1152 (1–2) (2007) 54–69, https://doi.org/10.1016/j.chroma.2007.01.032. Jun.

[21] P. Popp, P. Keil, L. Montero, M. Rückert, Optimized method for the determination of 25 polychlorinated biphenyls in water samples using stir bar sorptive extraction followed by thermodesorption-gas chromatography/mass spectrometry, J. Chromatogr. A 1071 (1–2) (2005) 155–162, https://doi.org/10.1016/j.chroma.2005.01.066. Apr.

[22] N. Ochiai, K. Sasamoto, F. David, P. Sandra, Recent developments of stir bar sorptive extraction for food applications: extension to polar solutes, J. Agric. Food Chem. 66 (28) (2018) 7249–7255, https://doi.org/10.1021/acs.jafc.8b02182. Jul.

[23] N. Maslamani, E. Manandhar, D.K. Geremia, B.A. Logue, ICE Concentration Linked with Extractive Stirrer (ICECLES), Anal. Chim. Acta 941 (2016) 41–48, https://doi.org/10.1016/j.aca.2016.09.003. Oct.

[24] N. Ochiai, K. Sasamoto, F. David, P. Sandra, Solvent-assisted stir bar sorptive extraction by using swollen polydimethylsiloxane for enhanced recovery of polar solutes in aqueous samples: application to aroma compounds in beer and pesticides in wine, J. Chromatogr. A 1455 (2016) 45–56, https://doi.org/10.1016/j.chroma.2016.05.085. Jul.

[25] P. Sandra, E. Baltussen, F. David, A. Hoffmann, 'Stir Bar Sorptive Extraction (SBSE) applied to environmental aqueous samples', Gerstel, Glob. Anal. Sol. 2/200.

[26] N. Gilart, R.M. Marcé, F. Borrull, N. Fontanals, New coatings for stir-bar sorptive extraction of polar emerging organic contaminants, TrAC Trends Anal. Chem. 54 (2014) 11–23, https://doi.org/10.1016/j.trac.2013.10.010. Feb.

[27] Z. Zhang, M.A. Mwadini, Z. Chen, Polytetrafluoroethylene-jacketed stirrer modified with graphene oxide and polydopamine for the efficient extraction of polycyclic aromatic hydrocarbons: sample preparation, J. Sep. Sci. 39 (20) (2016) 4011–4018, https://doi.org/10.1002/jssc.201600716. Oct.

[28] P. Poormoghadam, S. Bahar, Extraction of lead in human blood serum using functionalized metal-organic framework-coated glass magnet as adsorbent through stir bar sorptiven extraction, Microchem. J. 196 (2024) 109684, https://doi.org/10.1016/j.microc.2023.109684. Jan.

[29] M. Safaei, M.M. Foroughi, N. Ebrahimpoor, S. Jahani, A. Omid, M. Khatami, A review on metal-organic frameworks: synthesis and applications, TrAC Trends Anal. Chem. 118 (2019) 401–425, https://doi.org/10.1016/j.trac.2019.06.007. Sep.

[30] J. Sun, X. Lian, L. Wang, Z. Duan, Development and application of a robust imine-based covalent organic framework for stir bar sorptive extraction of estrogens in environmental water, Molecules 29 (23) (2024) 5763, https://doi.org/10.3390/molecules29235763. Dec.

[31] Z. Xiao, M. He, B. Chen, B. Hu, Polydimethylsiloxane/metal-organic frameworks coated stir bar sorptive extraction coupled to gas chromatography-flame photometric detection for the determination of organophosphorus pesticides in environmental water samples, Talanta 156–157 (2016) 126–133, https://doi.org/10.1016/j.talanta.2016.05.001. Aug.

[32] C. Zhong, M. He, H. Liao, B. Chen, C. Wang, B. Hu, Polydimethylsiloxane/covalent triazine frameworks coated stir bar sorptive extraction coupled with high performance liquid chromatography-ultraviolet detection for the determination of phenols in environmental water samples, J. Chromatogr. A 1441 (2016) 8–15, https://doi.org/10.1016/j.chroma.2016.02.073. Apr.

[33] Q. Zhang, X. Yao, M. He, B. Chen, N. Zhu, B. Hu, Porous aromatic framework/polydimethylsiloxane coated stir bar sorptive extraction coupled with high performance liquid chromatography-dioxide array detection of trace polychlorinated biphenyls analysis in environmental waters, J. Chromatogr. A 1688 (2023) 463709, https://doi.org/10.1016/j.chroma.2022.463709. Jan.

[34] W. Fan, M. Gao, M. He, B. Chen, B. Hu, Cyromazine imprinted polymers for selective stir bar sorptive extraction of melamine in animal feed and milk samples, Analyst 140 (12) (2015) 4057–4067, https://doi.org/10.1039/C5AN00325C.

[35] C. Wang, W. Zhou, X. Liao, W. Li, Z. Chen, Covalent immobilization of ionic liquid-based porous polymer onto poly(ether ether ketone) for stir bar sorptive extraction and its application in analysis of chlorophenoxy acid herbicides in soil, Talanta 208 (2020) 120442, https://doi.org/10.1016/j.talanta.2019.120442. Feb.

[36] J. Feng, H.M. Loussala, S. Han, X. Ji, C. Li, M. Sun, Recent advances of ionic liquids in sample preparation, TrAC Trends Anal. Chem. 125 (2020) 115833, https://doi.org/10.1016/j.trac.2020.115833. Apr.

[37] W. Fan, X. Mao, M. He, B. Chen, B. Hu, Development of novel sol–gel coatings by chemically bonded ionic liquids for stir bar sorptive extraction—application for the determination of NSAIDS in real samples, Anal. Bioanal. Chem. 406 (28) (2014) 7261–7273, https://doi.org/10.1007/s00216-014-8141-9. Nov.

[38] A. Chisvert, J.L. Benedé, J.L. Anderson, S.A. Pierson, A. Salvador, Introducing a new and rapid microextraction approach based on magnetic ionic liquids: stir bar dispersive liquid microextraction, Anal. Chim. Acta 983 (2017) 130–140, https://doi.org/10.1016/j.aca.2017.06.024. Aug.

[39] J.L. Benedé, J.L. Anderson, A. Chisvert, Trace determination of volatile polycyclic aromatic hydrocarbons in natural waters by magnetic ionic liquid-based stir bar dispersive liquid microextraction, Talanta 176 (2018) 253–261, https://doi.org/10.1016/j.talanta.2017.07.091. Jan.

[40] J.P. Koelmel, et al., An actionable annotation scoring framework for gas chromatography-high-resolution mass spectrometry, Exposome 2 (1) (2022) osac007, https://doi.org/10.1093/exposome/osac007. Mar.

[41] A. Curat, Elaboration de Phases stationnaires à haute stabilité thermique à base de liquide ionique pour la chromatographie en Phase gazeuse, Ph.D Thesis, University of Rouen Normandie, Mont Saint Aignan, 2015.

[42] A. Curat, S. Tisse, V. Agasse-Peulon, D. Villemin, P. Cardinael, Incorporation of imidazolium ionic liquids in GC stationary phases via the sol–gel process, Chromatographia 83 (3) (2020) 439–449, https://doi.org/10.1007/s10337-020-03854-7. Mar.

[43] Y. Jeon, et al., Structures of ionic liquids with different anions studied by infrared vibration spectroscopy, J. Phys. Chem. B 112 (15) (2008) 4735–4740, https://doi.org/10.1021/jp7120752. Apr.

[44] L. Cammarata, S.G. Kazarian, P.A. Salter, T. Welton, Molecular states of water in room temperature ionic liquids Electronic Supplementary Information available, Phys. Chem. Chem. Phys. 3 (23) (2001) 5192–5200, https://doi.org/10.1039/b106900d. http://www.rsc.org/suppdata/cp/b1/b106900d/. Nov.

[45] J.L. Anderson, D.W. Armstrong, High-stability ionic liquids. A new class of stationary phases for gas chromatography, Anal. Chem. 75 (18) (2003) 4851–4858, https://doi.org/10.1021/ac0345749. Sep.