# Multi-sorbent passive sampler for the preconcentration of contaminants with broad polarity spectrum in drinking water, including very polar compounds

Vincent Dufour, Guilhem Zerbini, Laure Wiest, Aurélie Fildier, Xavier Dauchy, Samuel Robert, Jerôme Enault, Mar Esperanza, Emmanuelle Vulliet

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## ► To cite this version:

Vincent Dufour, Guilhem Zerbini, Laure Wiest, Aurélie Fildier, Xavier Dauchy, et al. Multi-sorbent passive sampler for the preconcentration of contaminants with broad polarity spectrum in drinking water, including very polar compounds. Journal of Hazardous Materials, 2026, 501, pp.140754. 10.1016/j.jhazmat.2025.140754. hal-05517566

HAL Id: hal-05517566

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Submitted on 18 Feb 2026

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# Multi-sorbent passive sampler for the preconcentration of contaminants with broad polarity spectrum in drinking water, including very polar compounds

Vincent Dufour<sup>a, *,</sup>, Guilhem Zerbini<sup>a, †</sup>, Laure Wiest<sup>a, †</sup>, Aurélie Fildier<sup>a</sup>, Xavier Dauchy<sup>b, ‡</sup>, Samuel Robert<sup>c</sup>, Jerôme Enault<sup>c, †</sup>, Mar Esperanza<sup>c, †</sup>, Emmanuelle Vulliet<sup>a, *,</sup>

## HIGHLIGHTS

* A passive sampler with HLB, SAX, and SCX sorbents was developed.

* First passive sampler specifically suitable for ultra-polar compounds.

* Robust evaluation over 47 molecules, showing resilience to pH variations.

* Field tests revealed complementary sorbent for water contaminant monitoring.

* Detection of 37 molecules, including 20 with $logP < 1$ in drinking water.

## GRAPHICAL ABSTRACT

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## ARTICLE INFO

### Keywords:

Chemcatcher
PMOC
LC-MS/MS
High polarity
PMT

## ABSTRACT

The occurrence of Persistent and Mobile Organic Contaminants (PMOCs), especially very polar compounds (log P <1), remains poorly characterized in drinking water due to analytical limitations. These compounds are highly soluble, weakly retained on conventional $C_{18}$ materials, and may persist through treatment processes, raising concerns about potential health and environmental impacts. To address this challenge, we developed a passive sampler combining three complementary sorbents (HLB, SAX, and SCX) to enhance retention across a wide polarity range. The device was evaluated under controlled conditions (47 target substances, 3 concentrations, triplicates) to assess sorption performance and pH sensitivity. Results confirmed the complementarity of the sorbents with broad retention for HLB and more specific patterns for SAX and SCX. The tool was then deployed for 15 days in both raw and treated waters across seven drinking water treatment plants. A total of 37 contaminants were detected, including 20 with log P < 1. The treatment processes proved effective, with an average 13-fold reduction in the accumulated quantities between RW and TW, although the contamination profile in TW appeared more complex, likely reflecting presence of transformation products and residual highly polar compounds. Compounds with log P < 1 were found to pass more efficiently through drinking water treatment processes, consistent with their higher polarity and lower affinity for conventional removal pathways. By

<footnote><sup>a</sup> Université Claude Bernard Lyon 1, CNRS, ISA, UMR5280, 5 rue de la Doua, F-69100 Villeurbanne, France</footnote>

<footnote><sup>b</sup> ANSES, Laboratoire d'Hydrologie de Nancy, 40 Rue Lionnois, Nancy F-54000, France</footnote>

<footnote><sup>c</sup> SUEZ, CIRSEE (Centre International de Recherche Sur l'Éau et l'Environnement), 38 rue du président Wilson, Le Pecq 78230, France</footnote>

<footnote>* Corresponding authors.
E-mail addresses: dufour.vincent@live.fr (V. Dufour), emmanuelle.vulliet@isa-lyon.fr (E. Vulliet).</footnote>
integrating exposure over time, the sampler lowered detection limits and offered a more exhaustive contamination profile. This approach supports improved PMOC surveillance and lays the groundwork for future quantitative or untargeted monitoring strategies in drinking water systems.

# 1. Introduction

Water contamination in aquatic environments is a critical concern due to its ecological and health impacts. Chemical pollutants from industrial, agricultural, and domestic sources, such as pesticides and pharmaceuticals, are particularly problematic due to their ubiquity and persistence in water bodies [1,2]. Regulatory monitoring programs typically focus on a limited set of priority substances, which may represent only a small fraction of actual chemical contamination. Even broad LC-HRMS-based non-targeted screening methods capture only about 2 % of the estimated organic contaminant chemical space [3], highlighting the magnitude of the knowledge gap. Among the vast array of organic micropollutants, Persistent and Mobile Organic Contaminants (PMOCs) have recently gained attention because of their environmental mobility and resistance to degradation [4–7]. This category brings together chemicals from different uses (pesticides, pharmaceuticals, transformation products, etc.) based on common behavior: they often exhibit very low logP values (<1) or exist predominantly in ionic form at environmentally relevant pH values, making them difficult to retain [8–10]. Their persistence is particularly alarming: for instance, atrazine degradation products are still found in French aquatic ecosystems despite atrazine being banned since 2003, following the gradual degradation of atrazine trapped in agricultural soils [11,12].

To better characterize risk, European regulatory frameworks (ECHA) introduced additional hazard categories for such substances. PMOCs with specific physicochemical and toxicological properties may be further classified as Persistent, Mobile, and Toxic (PMT) or very Persistent and very Mobile (vPvM), two categories proposed to parallel the better-known PBT (Persistent, Bioaccumulative, and Toxic) and vPvB (very Persistent and very Bioaccumulative) substances [13]: while PBT/vPvB substances tend to accumulate in organisms, PMT/vPvM compounds pose a threat to drinking water resources due to their mobility in the aquatic continuum and poor removability by conventional treatments [6].

Monitoring PMOCs remains analytically challenging. Their concentrations typically fall in the ultra-trace range (pg.L⁻¹ to low ng.L⁻¹) [11, 14–17], yet they can be dangerous to aquatic environments at these levels. For instance, Tousova et al. (2017) [18] reported predicted no-effect concentrations (PNECs) below 10 ng.L⁻¹. Furthermore, environmental dynamics of PMOCs are complex, as illustrated by Halbach et al. (2021), who monitored pesticides in small agricultural streams in Germany over two years and reported strong correlations between contaminant concentrations and rainfall, with notably lower levels during dry periods [17]. For instance, they estimated that levels of 2-methyl-4-chlorophenoxyacetic acid ranged from 200 pg.L⁻¹ to 100 µg. L⁻¹, highlighting the need of a highly sensitive and robust analytical method. Traditional approaches like direct injection often lack sufficient sensitivity, making pre-concentration steps like solid-phase extraction (SPE) essential to reach the required detection limits [19]. In addition, their polarity (logP <1) limits retention on standard octadecyl-bonded silica (C₁₈) phases in LC-MS/MS analysis [8,20–22]. Alternative approaches involve specialized columns like HILIC [10,23], Hypercarb™ [24], ion exchange resins [25], or methods like supercritical fluid chromatography [10], which are not always compatible with routine workflows. This complexity is one of the main reasons why PMOCs are not consistently included in routine monitoring programs [6].

Passive sampling has emerged as a promising solution to address these constraints. By integrating contamination over time, passive samplers reduce quantification limits and improve the detection of episodic or fluctuating pollution events compared to grab sampling

[26–29]. Among available formats, Chemcatcher® samplers, composed of a sorptive phase or sorbent covered with a semi-permeable membrane, offer flexibility in targeting different contaminant classes depending on sorbent selection. Variants include reversed-phase sorbents such as C₁₈ and styrene-divinylbenzene reversed-phase sulfonate (SDB-RPS), as well as ion-exchange sorbents like styrene-divinylbenzene functionalized with carboxylic acid groups (SDB-XC), used respectively for the retention of hydrophobic and charged compounds [26,29–31]. A modified version without a membrane has also been deployed in groundwater to enhance uptake efficiency [26,30,32]. In this configuration, passive samplers achieve pre-concentration capabilities similar to SPE, a technique widely used in water analysis [33–35].

SPE with polymeric sorbents, particularly Hydrophilic-Lipophilic Balance (HLB) [36] is a reference for developing new passive sampling bounding-phases [17,31,32]. Most of these sorbents, including strong anion exchange (SAX), weak anion exchange (WAX), strong cation exchange (SCX), and weak cation exchange (WCX) sorbents, share a common styrene-divinylbenzene polymer backbone that tends to sorb hydrophobic chemicals [37–39]. Their functionalization varies: HLB incorporates n-vinylpyrrolidone for more hydrophilic retention, SAX uses quaternary amine groups for anion exchange, and SCX employs ethylbenzene sulfonic acid groups for cation exchange. Despite their potential, the use of ion exchange sorbents in passive sampling is still largely unexplored for passive sampling. Some materials, such as Molecularly Imprinted Polymers (MIP) tailored for specific very polar compounds like glyphosate [40], lack the versatility required for multi-residue analysis. A wide variety of sorbent phases are already available on the market for passive sampling applications [41] but many have not yet been evaluated for their suitability in sampling PMOC. Some studies, such as Baglietto et al. (2025) on POCIS [42], employ ion-exchange phases to target highly polar compounds, although many of these sorbents have not yet been evaluated for their suitability in sampling PMOCs. Other approaches, such as the diffusion-based microporous tube sampler described by Verhagen et al. (2020), rely on alternative passive sampler configurations rather than traditional sorbent-based uptake [43]. To date, there is a notable lack of Chemcatcher® configurations specifically optimized and validated for very polar compounds (logP <1).

The objective of this study was to develop and evaluate a new passive sampler combining three complementary sorbent phases (HLB, SAX, and SCX), with the aim of enabling broad sampling across a wide polarity range (logP –3.3–5.2), including PMOCs, and of assessing the performance of this new device. Sorption behaviors were first evaluated under controlled laboratory conditions and extraction protocols were optimized using a mixture of 30 reference compounds including pesticides, pharmaceuticals, transformation products and oxidation by-products. Analytical performances were assessed for each sorbent on an extended set of 47 relevant substances. Finally, samplers were deployed in seven drinking water treatment plants in France, which remain understudied compared to wastewater facilities [44], to assess their applicability for PMOC monitoring on field.

# 2. Material and methods

## 2.1. Chemicals, reagents and lab materials

Each analytical standard (purity >95 %) was acquired from Dr Ehrenstorfer (Augsburg - Germany), LGC (Teddington - UK), Merck (Darmstadt - Germany), or TCI Europe (Zwijndrecht - Belgium). Three types of AttractSPE® disks were used (Affinisep, Le Houlme - France):
HLB, anion exchange SR (SAX) and cation exchange SR (SCX). Acetone (Honeywell, Seelze - Germany), acetonitrile (Fisher Scientific, Loughborough - UK), isopropanol (Biosolve, Dieuse - France), methanol (Honeywell, Seelze - Germany) and water (Merck, Darmstadt - Germany) were all of LC-MS grade. Calcium sulfate dihydrate, magnesium sulfate heptahydrate, sodium bicarbonate and potassium chloride were purchased from Merck (Darmstadt - Germany), just like the sulfuric acid (95 %) and the nitric acid (65 %). The ammonium formate was purchased from Biosolve (Dieuse - France). The 15 mL polypropylene (PP) centrifuge tubes were purchased from Merck (Darmstadt - Germany), 50 mL PP centrifuge tubes from VWR (Strasbourg - France), 700 µL PP injection vials from Waters (Saint-Quentin en Yvelines - France), and 1.5 mL glass vials from Intechim (Montluçon - France). Formic acid (FA) of purity > 99 % was purchased from Biosolve.

## 2.2. Bonding phases selection

The passive samplers used in this study were derived from the original Chemcatcher® design and consisted of solid-phase disks (AttractSPE® disk) with a 47 mm diameter [32]. These polymeric sorbents are composed of a polystyrene-divinylbenzene backbone functionalized with distinct chemical moieties: HLB (hydrophilic-lipophilic balance), SAX (quaternary amine groups), and SCX (ethylbenzene sulfonic acid groups), presented in Figure SI 1.

The choice of strong ion exchange phases (SAX and SCX) for our sampler was driven by their ability to maintain consistent ionic retention across variable pH conditions, which is critical for reliable sampling of ionizable contaminants in drinking water. Strong ion-exchange sorbents feature permanently charged functional groups, making them less sensitive to pH fluctuations compared with weak exchangers whose functional groups can lose ionization and thereby retention capacity under environmental conditions [45]. In addition, a recent study demonstrated that a strong anion-exchange SPE method achieved significantly higher and more repeatable recoveries and lower matrix interferences compared with a generic mixed-mode weak anion-exchange method when analyzing acidic contaminants in drinking water [46]. Thus, SAX and SCX phases were selected to maximize coverage of the broad polarity and charge spectrum of contaminants of emerging concern, while ensuring robustness and reliability in field conditions.

## 2.3. Passive samplers conditioning

Up to four disks of the same type were placed in 50 mL PP tubes and sequentially immersed in solvent baths under rotary agitation at 10 RPM for 5 min, following a previously established protocol [30]. The conditioning solvents varied by binding-phase type: acetone, isopropanol, methanol, and water for HLB; acetone, methanol, water, 1 M sodium hydroxide, and water for SAX; and acetone, methanol, water, 50 % nitric acid, and water for SCX. After the final water rinse, the binding phases were ready for exposure. A detailed conditioning protocol is provided in Figure SI 2.

## 2.4. Lab experimentation

To maintain a controlled environment, laboratory tests were conducted in batches. First, a subset of 30 compounds was used for method development, specifically to design and optimize the sorption experiments (sorbent selection, experimental conditions, and data treatment). In a second step, the same experimental protocol was applied to an extended set of 47 target compounds for method validation and consolidation of performance, in order to cover a broader range of physicochemical properties (polarity, ionization state, molecular weight) and thus a wider diversity of sorption behaviors. Compounds are listed in Table 1.

After conditioning, each sorbent was immersed in 40 mL of synthetic

groundwater [47] (60 mg.L⁻¹ calcium sulfate, 60 mg.L⁻¹ magnesium sulfate, 90 mg.L⁻¹ sodium bicarbonate and 4 mg.L⁻¹ potassium chloride in ultrapure water) in a 50 mL PP centrifuge tube under rotary agitation at 10 RPM for precisely 1 h. Unless otherwise specified, the water was buffered at pH 7.5 and spiked with 30 analytical standards at varying concentrations (0, 100, 500, 1000 ng.L⁻¹, or 200 µg.L⁻¹). Compounds were selected based on molecular mass (84–419 g.mol⁻¹), logP (-3.3–5.1), and ionic charge at pH 7 Compounds were selected based on molecular mass (84–419 g.mol⁻¹), logP (−3.3–5.1), and ionic charge at pH 7. LogP and pKa values were retrieved from online databases [48–50], and experimentally derived values were systematically preferred over modelled estimates whenever available. In some batch experiments, the spiked synthetic water was analysed before and after passive sampler exposure to assess concentration differences and determine the sorption capacities of the binding phases.

## 2.5. Field sampling

To evaluate the performance of the sorbents under actual conditions and assess the occurrence of emerging contaminants, including PMOCs, 7 drinking water treatment plants across France were monitored. These sites were selected to cover a diversity of daily production volumes, treatment processes, and water sources (Table SI 1). Drinking water treatment processes varied across the sampled sites, ranging from simple chlorination (site1) to more advanced multi-barrier systems incorporating activated carbon filtration, ozonation, ultrafiltration, and UV disinfection. Stations 1, 2, and 7 are supplied with groundwater, while stations 3, 4, 5, and 6 treat surface water, reflecting the diversity of source water matrices considered in this study. Parallel sampling of raw water (RW) and treated water (TW) was conducted at each site to allow direct comparison of contaminant profiles before and after treatment.

For water sampling, three disks of each sorbent type were conditioned in the laboratory and mounted on a stainless-steel holder (Fig. 1), as described in previous work [30]. The stainless-steel holder consisted of two cylindrical cages: one inner (19 cm high, 4.5 cm diameter) made of fine mesh (0.25 × 0.25 cm²) and one outer with similar dimensions, to hold the sorbent phase disks. After conditioning, the entire setup was stored at + 4°C in 2 L high-density polyethylene bottles filled with LC-MS grade water until deployment. For field exposure, the holder was fully immersed at mid-height in a 35 L stainless steel tank continuously supplied with groundwater (100 L.h⁻¹ flow rate, bottom to top circulation) from a bypass pump for 15 days. The sampling period was chosen based on standard practices for passive samplers, including a previous study on groundwater contamination profile establishment [32]. Additionally, the stability of the AttractSPE® over a 14-day period has been demonstrated in recent work [38]. Both RW and TW of each sampling site were sampled at the same time and in the same conditions.

Following the exposure period, the binding phases were gently dried, individually wrapped in aluminum sheets, and frozen at −21°C until elution.

To monitor potential cross-contamination, three additional disks of each sorbent type were mounted on a stainless-steel holder and submerged in LC-MS grade water at + 4°C throughout the sampling period. These blanks were extracted alongside the environmental samples.

## 2.6. Binding phases elution

### 2.6.1. Optimization

The elution protocol was adapted from the procedure developed by Pinasseau *et al.* (2019) [30] originally designed for the same passive sampler configuration but using a different sorbent phase (SDB-XC). To optimize elution conditions, solid-phase disks were individually exposed to a mixture of 30 analytical standards (200 µg.L⁻¹) for one hour according to protocol described in Section 2.3, then dried overnight in a fume hood. Elution was performed using two successive 10 mL solvent treatments under rotary agitation (10 min, 90 RPM) in PP tubes.
<table><caption>**Table 1**
List and properties of the molecules analyzed [48].</caption><thead><tr><th>Compound</th><th>Raw formula</th><th>CAS number</th><th>Molecular mass (g.mol<sup>-1</sup>)</th><th>Log P</th><th>Basic pKa</th><th>Acid pKa</th><th>Ionic form at pH7*</th><th>Used for method development</th><th>Used for method validation</th></tr></thead><tbody><tr><td>Acephate</td><td>C<sub>4</sub>H<sub>10</sub>NO<sub>3</sub>PS</td><td>30560-19-1</td><td>183.17</td><td>-0.9</td><td>-</td><td>8.4</td><td>A</td><td></td><td>X</td></tr><tr><td>Acesulfame</td><td>C<sub>4</sub>H<sub>5</sub>NO<sub>4</sub>S</td><td>33665-90-6</td><td>163.15</td><td>-0.3</td><td>-</td><td>2</td><td>A</td><td></td><td>X</td></tr><tr><td>Acetazolamide</td><td>C<sub>4</sub>H<sub>6</sub>N<sub>4</sub>O<sub>3</sub>S<sub>2</sub></td><td>59-66-5</td><td>222.3</td><td>-0.3</td><td>-</td><td>7.2</td><td>A</td><td></td><td>X</td></tr><tr><td>Bentazon</td><td>C<sub>10</sub>H<sub>12</sub>N<sub>2</sub>O<sub>3</sub>S</td><td>25057-89-0</td><td>240.28</td><td>-0.5</td><td>-</td><td>3.3</td><td>A</td><td>X</td><td>X</td></tr><tr><td>CGA 369873<sup>1</sup></td><td>C<sub>10</sub>H<sub>12</sub>NO<sub>4</sub>S</td><td>2387071-47-6</td><td>265.26</td><td>1.4</td><td>-</td><td>-</td><td>A</td><td>X</td><td>X</td></tr><tr><td>Diclofenac</td><td>C<sub>14</sub>H<sub>11</sub>Cl<sub>2</sub>NO<sub>2</sub></td><td>15307-86-5</td><td>296.1</td><td>4.5</td><td>-2.1</td><td>4.2</td><td>A</td><td>X</td><td>X</td></tr><tr><td>Ioxynil</td><td>C<sub>7</sub>H<sub>3</sub>I<sub>2</sub>NO</td><td>1689-83-4</td><td>370.91</td><td>0.9</td><td>-</td><td>4</td><td>A</td><td>X</td><td>X</td></tr><tr><td>N-cyclohexylsulfamate</td><td>C<sub>6</sub>H<sub>13</sub>NO<sub>3</sub>S</td><td>139-05-9</td><td>179.24</td><td>-1.6</td><td>-</td><td>1.7</td><td>A</td><td>X</td><td>X</td></tr><tr><td>Oxybenzone</td><td>C<sub>14</sub>H<sub>12</sub>O<sub>3</sub></td><td>1491-59-4</td><td>228.24</td><td>3.8</td><td>-</td><td>7.1</td><td>A</td><td>X</td><td>X</td></tr><tr><td>Prosulfuron</td><td>C<sub>15</sub>H<sub>16</sub>F<sub>3</sub>N<sub>5</sub>O<sub>4</sub>S</td><td>94125-34-5</td><td>419.4</td><td>3.5</td><td>-</td><td>3.8</td><td>A</td><td></td><td>X</td></tr><tr><td>Saccharin</td><td>C<sub>7</sub>H<sub>5</sub>NO<sub>3</sub>S</td><td>81-07-2</td><td>183.19</td><td>0.9</td><td>-</td><td>1.3</td><td>A</td><td>X</td><td>X</td></tr><tr><td>Sulfadiazine</td><td>C<sub>10</sub>H<sub>10</sub>N<sub>4</sub>O<sub>2</sub>S</td><td>68-35-9</td><td>250.28</td><td>-0.2</td><td>2.1</td><td>7</td><td>A</td><td></td><td>X</td></tr><tr><td>Atenolol</td><td>C<sub>14</sub>H<sub>22</sub>N<sub>2</sub>O<sub>3</sub></td><td>29122-68-7</td><td>266.34</td><td>0.2</td><td>9.6</td><td>14.1</td><td>C</td><td>X</td><td>X</td></tr><tr><td>Chlormequat</td><td>C<sub>5</sub>H<sub>13</sub>ClN<sub>+</sub></td><td>70003-89-6</td><td>122.62</td><td>-3.3</td><td>-</td><td>-</td><td>C</td><td>X</td><td>X</td></tr><tr><td>Clothianidin</td><td>C<sub>6</sub>H<sub>8</sub>ClN<sub>5</sub>O<sub>2</sub>S</td><td>210880-92-5</td><td>249.68</td><td>0.7</td><td>11.1</td><td>-</td><td>C</td><td>X</td><td>X</td></tr><tr><td>Fenpropimorph</td><td>C<sub>20</sub>H<sub>33</sub>NO</td><td>67564-91-4</td><td>303.5</td><td>5.2</td><td>7.3</td><td>-</td><td>C</td><td>X</td><td>X</td></tr><tr><td>Imidacloprid desnitro</td><td>C<sub>9</sub>H<sub>11</sub>ClN<sub>4</sub></td><td>115970-17-7</td><td>210.66</td><td>0.7</td><td>11.5</td><td>-</td><td>C</td><td></td><td>X</td></tr><tr><td>Imidacloprid olefin</td><td>C<sub>9</sub>H<sub>8</sub>ClN<sub>5</sub>O<sub>2</sub></td><td>115086-54-9</td><td>253.64</td><td>0.6</td><td>-</td><td>-</td><td>C</td><td>X</td><td>X</td></tr><tr><td>Metformin</td><td>C<sub>4</sub>H<sub>11</sub>N<sub>5</sub></td><td>657-24-9</td><td>129.16</td><td>-2.6</td><td>12.4</td><td>-</td><td>C</td><td>X</td><td>X</td></tr><tr><td>Nitrosomorpholine</td><td>C<sub>4</sub>H<sub>8</sub>N<sub>2</sub>O<sub>2</sub></td><td>59-89-2</td><td>116.12</td><td>-2.6</td><td>8.3</td><td>-</td><td>C</td><td>X</td><td>X</td></tr><tr><td>Oseltamivir</td><td>C<sub>16</sub>H<sub>28</sub>N<sub>2</sub>O<sub>4</sub></td><td>196618-13-0</td><td>312.4</td><td>1</td><td>9.3</td><td>14</td><td>C</td><td></td><td>X</td></tr><tr><td>Quadrol</td><td>C<sub>14</sub>H<sub>32</sub>N<sub>2</sub>O<sub>4</sub></td><td>102-60-3</td><td>292.41</td><td>-0.7</td><td>14.2</td><td>-</td><td>C</td><td>X</td><td>X</td></tr><tr><td>Sitagliptin</td><td>C<sub>16</sub>H<sub>15</sub>F<sub>6</sub>N<sub>5</sub>O</td><td>486460-32-6</td><td>407.31</td><td>1.5</td><td>8.8</td><td>-</td><td>C</td><td></td><td>X</td></tr><tr><td>Sulpiride</td><td>C<sub>15</sub>H<sub>23</sub>N<sub>3</sub>O<sub>4</sub>S</td><td>15676-16-1</td><td>341.4</td><td>0.6</td><td>8.4</td><td>10.2</td><td>C</td><td></td><td>X</td></tr><tr><td>Adenine</td><td>C<sub>5</sub>H<sub>5</sub>N<sub>5</sub></td><td>73-24-5</td><td>135.13</td><td>-0.9</td><td>4.2</td><td>-</td><td>N</td><td></td><td>X</td></tr><tr><td>Ammeline</td><td>C<sub>3</sub>H<sub>5</sub>N<sub>5</sub>O</td><td>645-92-1</td><td>127.11</td><td>-1.8</td><td>-</td><td>9</td><td>N</td><td>X</td><td>X</td></tr><tr><td>Atrazine</td><td>C<sub>8</sub>H<sub>14</sub>ClN<sub>5</sub></td><td>1912-24-9</td><td>215.68</td><td>2.6</td><td>1.6</td><td>-</td><td>N</td><td>X</td><td>X</td></tr><tr><td>Boscalid</td><td>C<sub>18</sub>H<sub>12</sub>Cl<sub>2</sub>N<sub>2</sub>O</td><td>188425-85-6</td><td>343.2</td><td>3</td><td>-</td><td>-</td><td>N</td><td>X</td><td>X</td></tr><tr><td>Cyromazine</td><td>C<sub>6</sub>H<sub>10</sub>N<sub>6</sub></td><td>66215-27-8</td><td>166.18</td><td>-0.1</td><td>5.2</td><td>-</td><td>N</td><td>X</td><td>X</td></tr><tr><td>DEA<sup>2</sup></td><td>C<sub>6</sub>H<sub>10</sub>ClN<sub>5</sub></td><td>6190-65-4</td><td>187.63</td><td>1.5</td><td>4.4</td><td>14.6</td><td>N</td><td>X</td><td>X</td></tr><tr><td>DEA-OH<sup>3</sup></td><td>C<sub>6</sub>H<sub>11</sub>N<sub>5</sub>O</td><td>19988-24-0</td><td>169.19</td><td>-0.6</td><td>X</td><td>X</td><td>N</td><td></td><td>X</td></tr><tr><td>DEDIA<sup>4</sup></td><td>C<sub>3</sub>H<sub>4</sub>ClN<sub>5</sub></td><td>3397-62-4</td><td>145.55</td><td>-0.1</td><td>X</td><td>X</td><td>N</td><td>X</td><td>X</td></tr><tr><td>Dimethenamide-p</td><td>C<sub>12</sub>H<sub>18</sub>ClNO<sub>2</sub>S</td><td>163515-14-8</td><td>275.8</td><td>1.9</td><td>-</td><td>-</td><td>N</td><td>X</td><td>X</td></tr><tr><td>Dimethenamid-OXA<sup>5</sup></td><td>C<sub>12</sub>H<sub>17</sub>NO<sub>4</sub>S</td><td>380412-59-9</td><td>271.33</td><td>-2.3</td><td>-</td><td>-</td><td>N</td><td>X</td><td>X</td></tr><tr><td>Dinotefuran</td><td>C<sub>7</sub>H<sub>14</sub>N<sub>4</sub>O<sub>3</sub></td><td>165252-70-0</td><td>202.21</td><td>-0.5</td><td>-</td><td>12.6</td><td>N</td><td></td><td>X</td></tr><tr><td>Imidacloprid</td><td>C<sub>9</sub>H<sub>10</sub>ClN<sub>5</sub>O<sub>2</sub></td><td>138261-41-3</td><td>255.66</td><td>0.6</td><td>-</td><td>-</td><td>N</td><td>X</td><td>X</td></tr><tr><td>Melamine</td><td>C<sub>3</sub>H<sub>6</sub>N<sub>6</sub></td><td>108-78-1</td><td>126.12</td><td>-1.4</td><td>5</td><td>-</td><td>N</td><td>X</td><td>X</td></tr><tr><td>Metolachlor</td><td>C<sub>15</sub>H<sub>22</sub>ClNO<sub>2</sub></td><td>87392-12-9</td><td>283.79</td><td>3.1</td><td>-</td><td>-</td><td>N</td><td>X</td><td>X</td></tr><tr><td>N,N-dimethylsulfamide</td><td>C<sub>2</sub>H<sub>8</sub>N<sub>2</sub>O<sub>2</sub>S</td><td>3984-14-3</td><td>124.17</td><td>-0.8</td><td>-</td><td>10.6</td><td>N</td><td>X</td><td>X</td></tr><tr><td>Omethoate</td><td>C<sub>5</sub>H<sub>12</sub>NO<sub>4</sub>PS</td><td>1113-02-6</td><td>213.19</td><td>-0.7</td><td>-</td><td>-</td><td>N</td><td></td><td>X</td></tr><tr><td>Prosulfocarb</td><td>C<sub>14</sub>H<sub>21</sub>NOS</td><td>52888-80-9</td><td>251.39</td><td>3.9</td><td>-</td><td>-</td><td>N</td><td></td><td>X</td></tr><tr><td>Terbutryn</td><td>C<sub>10</sub>H<sub>19</sub>N<sub>5</sub>S</td><td>886-50-0</td><td>241.36</td><td>3.7</td><td>4.3</td><td>-</td><td>N</td><td>X</td><td>X</td></tr><tr><td>Theobromine</td><td>C<sub>7</sub>H<sub>8</sub>N<sub>4</sub>O<sub>2</sub></td><td>83-67-0</td><td>180.16</td><td>-0.8</td><td>-0.9</td><td>9.9</td><td>N</td><td></td><td>X</td></tr><tr><td>Gabapentine</td><td>C<sub>9</sub>H<sub>17</sub>NO<sub>2</sub></td><td>60142-96-3</td><td>171.24</td><td>-1.1</td><td>10.7</td><td>3.7</td><td>Z</td><td>X</td><td>X</td></tr><tr><td>5-fluorocytosine</td><td>C<sub>4</sub>H<sub>4</sub>FN<sub>3</sub>O</td><td>2022-85-7</td><td>129.09</td><td>-1.1</td><td>10.7</td><td>3.3</td><td>Z</td><td></td><td>X</td></tr><tr><td>Acyclovir</td><td>C<sub>8</sub>H<sub>11</sub>N<sub>5</sub>O<sub>3</sub></td><td>59277-89-3</td><td>225.2</td><td>-1.8</td><td>9.3</td><td>2.5</td><td>Z</td><td></td><td>X</td></tr><tr><td>Amitrole</td><td>C<sub>2</sub>H<sub>4</sub>N<sub>4</sub></td><td>61-82-5</td><td>84.08</td><td>-1</td><td>10.7</td><td>4.2</td><td>Z</td><td>X</td><td>X</td></tr></tbody></table>

<footnote n="1">¹: dimethachlor metabolite CGA-369873; ²: desetylatrazine; ³: desethylatrazine-2-hydroxy; ⁴: desethyl deisopropylatrazine; ⁵: dimethenamid oxanilic acid</footnote>

<footnote>*: A: anion; C: cation; N: neutral; Z: zwitterion</footnote>
<figure><img src="image_5.png" /><figcaption>Fig. 1. Detailed representation of the exposure system for field monitoring.</figcaption></figure>

Acetone and methanol (MeOH) were selected as primary eluents due to their frequent use in similar applications [32,37], and several acidic and basic conditions were tested to enhance the desorption of ionizable compounds.

For HLB, six solvent combinations were assessed: (1) MeOH, (2) acetone, (3) MeOH + 0.1 % FA, (4) MeOH + 1 % FA, (5) acetone followed by MeOH + 0.1 % FA, and (6) acetone followed by MeOH + 1 % FA. For SAX and SCX, five conditions were tested: (A) MeOH + 10 % H₂SO₄, (B) MeOH + 1 % H₂SO₄, (C) MeOH + 10 % FA, (D) 50 mM NaOH in MeOH, and (E) 50 mM NaOH in MeOH followed by MeOH + 1 % H₂SO₄.

To assess recovery performance, eluates were evaporated to ~5 mL, pooled by sample and centrifuged (10 min, 0°C, 11,000 RCF) to remove precipitates. Supernatant was transferred into a new 15 mL PP tube then evaporated to dryness and reconstituted in 500 µL of acetonitrile (ACN) prior to analysis. The detailed protocol is presented in Figure SI 2.

### 2.6.2. Final elution protocols

After thawing, the sorbent phases were dried overnight in a fume hood. Each was then placed in a 15 mL PP tube and eluted using two successive 10 mL solvent treatments under rotary agitation (90 RPM, 10 min). For SAX and SCX, elution was performed with 50 mM NaOH in MeOH, followed by 1 % H₂SO₄ in MeOH. HLB phases were eluted with two successive baths of MeOH containing 0.1 % FA. The rest of the protocol is identical to that described in section 2.5.1. (Figure SI 2).

## 2.7. LC-MS/MS

The 47 target chemicals (Table 1) were analyzed using a 1290 Infinity UPLC system (Agilent Technologies, Massy, FR) coupled with a 5500 QTRAP mass spectrometer (Sciex, Villebon-sur-Yvette, FR). Two chromatographic methods were employed.

The first used an Acclaim RSLC C₁₈ column (2.1 × 100 mm, 2.2 µm particles, Thermo Fischer Scientific), with mobile phases composed of (A) water/MeOH (90/10, v/v) and (B) MeOH, both containing 5 mM ammonium formate and 0.01 % FA. This method targeted moderately polar analytes in positive electrospray ionization (ESI) mode.

The second method utilized a SeQuant® ZIC-HILIC column (2.1 × 100 mm, 3.5 µm particle, Sigma-Aldrich) for both positive and negative ESI mode. Mobile phases consisted of (A) ACN/10 mM ammonium formate in water (95/5, v/v); and (B) ACN/10 mM ammonium formate in water (50/50, v/v). Chromatographic and mass spectrometric parameters for both methods are detailed in Table SI 2 and Table SI 3.

Injection volume was set at 10 µL for passive sampler and 20 µL for water samples. Water samples were directly injected for C₁₈ analysis, whereas for HILIC, 500 µL of water was evaporated to dryness and

reconstituted in 250 µL of ACN. A synthetic water sample was enriched to the same concentration and evaporated in parallel with the samples in order to calculate recovery rates and compensate for any losses during the process. Passive sampler extracts were diluted 10 times before injection: in a mix of 5 mM ammonium formate in water + 0.01 % FA for C₁₈ analysis, and in ACN for HILIC. To minimize analyte loss through adsorption, PP vials were systematically used for HILIC (polar compounds), while glass vials were employed for C₁₈ analysis (less polar compounds).

## 2.8. Validation and evaluation of binding performances

Validation was performed according to SANTE guideline "Analytical Quality Control and Method Validation Procedures for Pesticide Residues Analysis in Food and Feed" [51]. Extracts were quantified using matrix-matched calibration to ensure accuracy and reliability. Procedural blanks (non-exposed binding phases), extracted alongside the samples, were spiked with the analytical standards before injection to simulate accumulation levels of 0, 2, 4, 12, 20, 30 and 40 ng.disk⁻¹. Quantification was based on second order polynomial regressions for each analyte, all R² were all > 0.99. A similar procedure was applied for water analysis using synthetic water spiked with the standards at 0, 50, 100, 500, 750, 1000 ng.L⁻¹. The limit of detection (LOD) was defined as the lowest concentration corresponding to a signal-to-noise ratio of 10. The limit of quantification (LQQ) determined during validation corresponds to the lowest calibration point for which the recovery rates of the calibration range exhibit a variability of less than 20 %.

Because matrix-matched calibration based on post-extraction spiking does not, by itself, correct for extraction losses, compound-specific extraction recoveries determined during validation were systematically applied to field samples estimated concentrations in order to avoid overestimation and to ensure accurate quantification. The peak areas of compounds detected in blanks were subtracted from sample signals to further ensure reliable results.

Two key parameters were calculated to evaluate binding performance: percent sorbed (%SORBED), representing the proportion of analyte removed from solution by the binding phase relative to a control without sorbent, and extraction recovery (ER), representing the proportion of the adsorbed analyte successfully recovered after extraction, accounting for losses due to sorption onto the tube walls. The calculations are detailed in Eq.1 and Eq.2. In these equations, C*SORBENT* is the residual dissolved concentration (ng.L⁻¹) measured in the exposure solution containing a binding phase after 1 h of exposure, while C*EMPTY* is the residual dissolved concentration (ng.L⁻¹) in the control tube without sorbent. Q*REC* corresponds to the amount of analyte recovered after extraction (ng), Q*exp* to the total quantity of analyte initially present in the exposure solution (ng), and S*tube* to the percentage of analyte
sorbed onto the tube material during exposure (%). These equations respectively describe (I) the sorption capacity of the binding phase relative to the control and (II) the extraction recovery, while accounting for potential losses due to sorption onto the tube walls.

$$ \%_{\text{SORBED}} = 100 - C_{\text{SORBENT}}/C_{\text{EMPTY}} \times 100 \quad (1) $$

$$ ER = \frac{Q_{\text{REC}}}{Q_{\text{EXP}} - Q_{\text{EXP}} \times S_{\text{tube}}/100} \times 100 \quad (2) $$

# 3. Results and discussion

## 3.1. Sorption on tube

Plastic labware was preferred over glassware, as polar compounds are known to adsorb onto silanol groups present on glass surfaces, potentially leading to analyte loss and biased quantification. However, as with all plastics, the PP tubes may interact with the analytes, sorbing organic contaminants and reducing the quantities available for phase sorption [52,53], inducing lower extraction recoveries. The interaction between the PP tube and the analytes was assessed (Figure SI 3). Minimal sorption (<30 %) was observed for 22 out of 30 compounds, while 6 compounds showed moderate sorption (30–50 %), including boscalid, DEDIA (desethyl deisopropylatrazine), N,N-dimethylsulfamide, metolachlor, nitrosomorpholine, and terbutryn. In contrast, 2 compounds (fenpropimorph and oxybenzone) exhibited strong sorption (>90 %). PP is known to establish hydrophobic interactions with medium-polar to non-polar chemicals, which explains the high sorption rates of oxybenzone (logP 3.8) and fenpropimorph (logP 5.1). However, recent studies on nano- and microplastic particles have shown that PP can also sorb polar compounds via electrostatic interactions [53], which may explain the slight sorption of chlormequat (logP −3.3) and amitrole (logP −1). These results highlight the necessity of carefully selecting sample containers when analyzing trace levels of PMOCs.

## 3.2. Sorption capacity of the binding phases

The sorption capacities of HLB, SAX, and SCX, were assessed by comparing analyte concentration in synthetic water spiked with 30 standards at 500 ng.L⁻¹, after 1 h of exposure, with or without binding phases (Table SI 4–6). Overall, the three phases exhibited strong and complementary retention performances: 97 % of the compounds were retained by HLB (all but chlormequat), and all 30 compounds were retained by both SAX and SCX (including chlormequat). Sorption rates above 50 % were achieved for 67 % (n = 20), 77 % (n = 23), and 83 % (n = 25) of compounds with HLB, SAX, and SCX, respectively.

Retention efficiency was partly driven by the ionization state of analytes. Among well sorbed compounds (>50 % retention), HLB retained 70 % of anions, 75 % of cations, and 64 % of neutral compounds. In comparison, SAX and SCX showed a better affinity for charged compounds: SAX retained 86 % of anions, 88 % of cations, and 71 % of neutral compounds, while SCX retained 71 % of anions, 88 % of cations, and 86 % of neutral compounds. These results highlight the ionic selectivity of SAX and SCX, although all three sorbents exhibited broad-spectrum retention across different charge states.

When focusing on molecular polarity, SCX retained 75 % of highly polar compounds (logP <1), followed by SAX (65 %) and HLB (50 %). This confirms previous reports that HLB is most effective for compounds with logP between 1 and 3 [39], while SAX and SCX benefit from additional ionic interactions that improve retention of polar analytes. All phases efficiently retained less polar compounds (logP >1), indicating that nonpolar interactions with the polymer backbone play a consistent role. Some analytes confirmed expected retention patterns. Metformin, a permanently cationic compound, was retained only by SCX, and N-cyclohexylsulfamate (anionic) exclusively by SAX, aligning with their respective exchange mechanisms. Gabapentin and amitrole,

both zwitterionic, were retained by SCX, likely due to their amine groups, and gabapentin was also efficiently captured by SAX, probably through its carboxylic acid moiety.

However, several cases revealed unexpected behaviors. Clothianidin, imidacloprid, and terbutryn were well retained on all three phases despite differing functionalities, suggesting dominant non-specific interactions, possibly π-π stacking or Van der Waals forces with the common styrene-divinylbenzene backbone, as previously observed for chloro- and methylthio-triazines [39]. Yet atrazine, a related compound, was only well recovered by HLB, likely due to variations in elution protocols.

Finally, some apparent cross-retention was observed between SAX and SCX. For instance, bentazon (anionic) was unexpectedly retained on SCX, and chlormequat (cationic) on SAX. These observations may reflect secondary interactions (e.g. hydrogen bonding, π-π interactions) beyond the primary ionic exchange mechanism. Such retention patterns underscore that, despite sharing a polymeric matrix [38] the chemical functionalities of the sorbents drive distinct and sometimes overlapping affinities depending on analyte structure.

To conclude, the comparative sorption study of HLB, SAX, and SCX phases revealed that while all three exhibit strong retention capacities, SAX and SCX offer superior performance for charged and polar compounds due to their ionic functionalities. HLB, although less selective, ensures broad-spectrum retention, particularly for moderately polar compounds. These findings support the strategic use of mixed-phase extraction to broaden PMOC coverage.

## 3.3. Impact of pH on retention capacity

Since pH can influence solute-sorbent interactions by altering the ionic form of analytes and, in some cases, the properties of binding phases (particularly in ion-exchange materials such as SCX and SAX) [31], the effect of pH on compound retention was assessed at 6.5, 7.5, and 8.5, representative of typical French surface and groundwater conditions [54]. Most compounds exhibited stable sorption capacity across this pH range, with relative standard deviations (RSD) across replicates and pH generally below 20 %, confirming the robustness of the binding phases under environmental conditions (Tables SI 4–6). At least one phase retained each compound effectively (sorption >50 %) at all pH values, except for three highly polar compounds (nitrosomorpholine, saccharin, and dimethachlor metabolite CGA-369873), which showed poor and inconsistent retention, possibly due to insufficient affinity for the phases tested.

Some retention patterns aligned with expectations based on sorbent chemistry. For instance, metformin, a permanent cation, was retained exclusively by SCX, and N-cyclohexylsulfamate, an anion, only by SAX, consistent with their respective ionic selectivity. Similarly, gabapentin, an amphoteric compound, exhibited strong retention on SAX and SCX, but poor affinity for HLB, underlining the importance of electrostatic interactions.

However, certain compounds displayed unexpected behavior. Oxybenzone, transitioning from neutral to anionic across the pH range, was consistently retained (>95 %) by all phases. This suggests that retention may, in some cases, be driven more by π-π stacking or hydrophobic interactions with the common polymer backbone (styrene-divinylbenzene) than by ionic interactions. Conversely, fenpropimorph, shifting from cationic to neutral with increasing pH (pKa ≈7.3), showed steady retention on SAX, but a marked decrease on SCX and HLB at intermediate pH, likely due to weakened ionic and hydrophobic interactions. Finally, quadrol, which was poorly retained by SAX but efficiently captured by HLB and SCX, illustrates that polar moieties in HLB can be as effective as cation-exchange mechanisms for certain analytes.

These results highlight the value of combining complementary sorbents to ensure broad-spectrum capture, regardless of molecular charge or pH variations.
### 3.4. Elution protocol optimization

To compare the performance of the different protocols and sorbents, LC-MS/MS peak intensities were normalized to the maximum detected intensities, and only peaks exceeding 20 % of the maximum were considered significant (Fig. 2). Of the 30 compounds analyzed, the tested conditions enabled the detection of 25–30 compounds for HLB (conditions 1–6), 14–27 for SAX (conditions A to E), and 24–29 for SCX (conditions A to E).

For HLB, MeOH (1) enabled the elution of more compounds than acetone (2). Additionally, the presence of 0.1 % FA (3) increased both signal intensity and the number of detected compounds, whereas 1 % FA (4) reduced both metrics. Due to its chemical structure, the HLB sorbent is highly versatile, retaining cations, anions, and neutral compounds. The most effective elution protocol for HLB was condition 3 (MeOH + 0.1 % FA), which provided the highest detection frequencies for cations (60 %), anions (88 %), and neutral compounds (80 %), with 22 standards detected overall. No zwitterionic compounds were detected for HLB sorbent among tested elution protocols.

For SAX and SCX, only MeOH-based eluents were tested. Acidified MeOH (H₂SO₄ or FA), basic MeOH (NaOH), and combinations of both were evaluated. For SAX, manufacturer recommendations suggested acidification with 3 % FA, while previous study reported optimal elution with 10 % H₂SO₄ [55]. In our study, MeOH acidified with H₂SO₄ allowed the detection of 13 % and 25 % of anions with both 1 % (A) and 10 % (B) acidification, respectively. Conversely, 10 % FA (C) led to no anion detection. The highest anion detection frequency (50 %) was archived with condition D (50 mM NaOH in MeOH), suggesting that neutralizing the binding phase's functional groups is more effective than neutralizing the analytes themselves. However, the high NaOH concentration led to rapid clogging of the mass spectrometer. The best compromise was condition E (50 mM NaOH in MeOH followed by MeOH + 1 % H₂SO₄), enabling the detection of 25 % of anions, 47 % of neutral compounds, 60 % of cations, and all zwitterionic compounds. Although sodium sulfate precipitation occurred in the combined eluates, the solution remained compatible with LC-MS analysis after two centrifugation steps.

For SCX, the same conditions as for SAX were tested. MeOH + 10 % FA elution (C) did not release cations. Elution with NaOH alone (D) was excluded for the same reasons as above. MeOH acidified with H₂SO₄ (conditions A and B), both allowed the extraction of 86 % of cations,

while also enabling the detection of some anionic (13 % and 25 %, respectively), neutral (33 % and 47 %, respectively) and zwitterionic (100 %) compounds. The most effective SCX protocol was condition E (50 mM NaOH in MeOH followed by MeOH + 1 % H₂SO₄), detecting all cations and zwitterions, 60 % of neutral compounds and 38 % of anions, highlighting the advantage of modifying both the ionic charge of analytes and the functional groups of the sorbent phase.

In conclusion, elution protocols 3 (for HLB) and E (for SAX and SCX) provided the highest detection frequencies while remaining compatible with the LC-MS analytical system. These protocols were selected for further validation. The normalized intensities of the 30 analytes for each sampling sorbent are shown in Figure SI 4. The three phases of the passive sampler exhibit complementary recovery capabilities for very polar to moderately polar contaminants. A passive sampler using a single sorbent type would provide only a partial view of environmental contamination, whereas a multi-sorbent sampler would offer broader and more representative coverage.

### 3.5. Evaluation of binding phases performances

Validation was performed according to the SANTE guideline [51]. Experiments were conducted in triplicate on three different days, at pH 7.5, with 47 standards at 100, 500 and 1000 ng·L⁻¹. Synthetic groundwater and passive sampler extracts were analyzed to estimate the sorption capacity of each sorbent. Results are summarized in Table 2 and Table SI 7.

Calibration curves showed excellent linearity for all analytes (R² >0.99). Low-level contamination (< 5 % of the nominal concentration) was occasionally detected in blank extracts for a limited number of compounds (Table 2) and was systematically subtracted from sample signals to prevent false positives. LOD values ranged from 0.01 to 8 ng·disk⁻¹. Overall, 75 % of the LODs were below 0.25 ng·disk⁻¹ for HLB, 0.42 ng·disk⁻¹ for SAX and 0.77 ng·disk⁻¹ for SCX, while 50 % were below 0.07, 0.16 and 0.6 ng·disk⁻¹, respectively, indicating high sensitivity. The highest LODs were obtained for ammeline with HLB, acetazolamide with SAX and acyclovir with SCX, in line with their ionisation and expected interactions with the sorbents (poor retention on HLB for ammeline; strong binding on SAX/SCX for acetazolamide and acyclovir, leading to low recoveries).

ER and %SORBED (Section 2.8) were determined for all 47 compounds. Eight compounds were not recovered by any sorbent (recovery <20 %

<figure><img src="image_6.png" /><figcaption>**Fig. 2.** Detection frequency of anions, cations, neutral and zwitterionic analytical standards in HLB, SAX and SCX phases according to the extraction protocol involved after a standardized exposure (with 1: MeOH, 2: acetone, 3: MeOH +0.1 % FA, 4: MeOH +1 % FA, 5: acetone then MeOH +0.1 % FA, 6: acetone then MeOH +1 % FA, A: MeOH +1 % H₂SO₄, B: MeOH +10 % H₂SO₄, C: MeOH +10 % FA, D: NaOH 50 mM in MeOH, E: NaOH 50 mM in MeOH then MeOH +1 % H₂SO₄).</figcaption></figure>
<table><caption>**Table 2**

Analytical parameters of the validated method (LOD: limit of detection; %SORBED: the proportion of analyte sorbed by the binding phase).</caption><thead><tr><th rowspan="2">Molecules</th><th colspan="3">HLB (n = 3)</th><th colspan="3">SAX (n = 3)</th><th colspan="3">SCX (n = 3)</th><th colspan="2">Blanks (n = 27)</th></tr><tr><th>LOD<br>(ng.disk<sup>-1</sup>)</th><th>R<sup>2</sup></th><th>%SORBED<br>± RSD</th><th>LOD<br>(ng.disk<sup>-1</sup>)</th><th>R<sup>2</sup></th><th>%SORBED<br>± RSD</th><th>LOD<br>(ng.disk<sup>-1</sup>)</th><th>R<sup>2</sup></th><th>%SORBED<br>± RSD</th><th>Min-max<br>(ng.disk<sup>-1</sup>)</th><th>DF<br>(%)</th></tr></thead><tbody><tr><td>5-fluorocytosine</td><td>0.02</td><td>0.9986</td><td>53 ± 18</td><td>0.02</td><td>0.9943</td><td>80 ± 13</td><td>0.02</td><td>0.9987</td><td>100 ± 0</td><td>0-0</td><td>0</td></tr><tr><td>Acephate</td><td>0.33</td><td>0.9993</td><td>35 ± 43</td><td>0.63</td><td>0.9969</td><td>61 ± 57</td><td>1.08</td><td>0.9947</td><td>82 ± 38</td><td>0-0</td><td>0</td></tr><tr><td>Acesulfame</td><td>0.01</td><td>0.9990</td><td>46 ± 27</td><td>0.15</td><td>0.9977</td><td>15 ± 101</td><td>0.01</td><td>0.9980</td><td>29 ± 66</td><td>0-0</td><td>0</td></tr><tr><td>Acetazolamide</td><td>0.11</td><td>0.9979</td><td>76 ± 16</td><td>1.83</td><td>0.9950</td><td>100 ± 0</td><td>3.67</td><td>0.9976</td><td>95 ± 9</td><td>0-0</td><td>0</td></tr><tr><td>Acyclovir</td><td>0.13</td><td>0.9995</td><td>75 ± 29</td><td>0.10</td><td>0.9953</td><td>42 ± 57</td><td>5.16</td><td>0.9995</td><td>96 ± 12</td><td>0-0</td><td>0</td></tr><tr><td>Adenine</td><td>0.01</td><td>0.9999</td><td>12 ± 70</td><td>0.08</td><td>0.9980</td><td>92 ± 6</td><td>0.15</td><td>0.9976</td><td>96 ± 3</td><td>0.2-1.9</td><td>26</td></tr><tr><td>Amitrole</td><td>0.01</td><td>0.9998</td><td>0 ± 0</td><td>0.39</td><td>0.9939</td><td>0 ± 0</td><td>4.22</td><td>0.9979</td><td>88 ± 15</td><td>0-0</td><td>0</td></tr><tr><td>Ammeline</td><td>8.00</td><td>0.9977</td><td>74 ± 42</td><td>0.25</td><td>0.9947</td><td>13 ± 110</td><td>0.83</td><td>0.9979</td><td>36 ± 92</td><td>2.7-9.7</td><td>19</td></tr><tr><td>Atenolol</td><td>0.08</td><td>0.9981</td><td>77 ± 8</td><td>0.04</td><td>0.9980</td><td>69 ± 12</td><td>0.06</td><td>0.9952</td><td>83 ± 7</td><td>0-0</td><td>0</td></tr><tr><td>Atrazine</td><td>0.02</td><td>0.9986</td><td>92 ± 3</td><td>0.02</td><td>0.9995</td><td>88 ± 7</td><td>0.02</td><td>0.9994</td><td>96 ± 2</td><td>0-0</td><td>0</td></tr><tr><td>Bentazon</td><td>0.01</td><td>0.9975</td><td>75 ± 6</td><td>0.50</td><td>0.9977</td><td>49 ± 26</td><td>0.01</td><td>0.9982</td><td>90 ± 5</td><td>0-0</td><td>0</td></tr><tr><td>Boscalid</td><td>0.03</td><td>0.9991</td><td>99 ± 1</td><td>0.02</td><td>0.9973</td><td>98 ± 2</td><td>0.04</td><td>0.9964</td><td>93 ± 4</td><td>0-0</td><td>0</td></tr><tr><td>CGA-369873<sup>1</sup></td><td>0.01</td><td>0.9997</td><td>82 ± 6</td><td>0.01</td><td>0.9998</td><td>22 ± 90</td><td>0.01</td><td>0.9968</td><td>74 ± 41</td><td>0-0</td><td>0</td></tr><tr><td>Chlormequat</td><td>0.01</td><td>0.9993</td><td>3 ± 300</td><td>0.07</td><td>0.9965</td><td>60 ± 76</td><td>0.09</td><td>0.9987</td><td>69 ± 22</td><td>0-0</td><td>0</td></tr><tr><td>Clothianidin</td><td>0.08</td><td>0.9975</td><td>83 ± 5</td><td>0.04</td><td>0.9995</td><td>97 ± 3</td><td>0.22</td><td>0.9994</td><td>81 ± 6</td><td>0-0</td><td>0</td></tr><tr><td>Cyromazine</td><td>0.01</td><td>0.9993</td><td>44 ± 15</td><td>0.06</td><td>0.9991</td><td>25 ± 62</td><td>0.04</td><td>0.9978</td><td>99 ± 3</td><td>0-0</td><td>0</td></tr><tr><td>DEA<sup>2</sup></td><td>0.01</td><td>0.9985</td><td>80 ± 5</td><td>0.03</td><td>0.9995</td><td>74 ± 10</td><td>0.01</td><td>0.9981</td><td>91 ± 2</td><td>0-0</td><td>0</td></tr><tr><td>DEA-OH<sup>3</sup></td><td>0.16</td><td>0.9978</td><td>47 ± 8</td><td>0.05</td><td>0.9965</td><td>69 ± 19</td><td>0.15</td><td>0.9978</td><td>86 ± 8</td><td>0.2-0.3</td><td>11</td></tr><tr><td>DEDIA<sup>4</sup></td><td>1.02</td><td>0.9965</td><td>40 ± 32</td><td>0.77</td><td>0.9984</td><td>51 ± 28</td><td>0.94</td><td>0.9975</td><td>51 ± 57</td><td>0-0</td><td>0</td></tr><tr><td>Diclofenac</td><td>0.07</td><td>0.9983</td><td>93 ± 3</td><td>0.30</td><td>0.9989</td><td>100 ± 0</td><td>0.14</td><td>0.9997</td><td>98 ± 2</td><td>0.1-0.2</td><td>11</td></tr><tr><td>Dimethenamide-p</td><td>0.01</td><td>0.9977</td><td>92 ± 5</td><td>0.03</td><td>0.9990</td><td>89 ± 7</td><td>0.01</td><td>0.9944</td><td>87 ± 3</td><td>0-0</td><td>0</td></tr><tr><td>Dimethenamid-OXA<sup>5</sup></td><td>0.76</td><td>0.9983</td><td>72 ± 29</td><td>0.44</td><td>0.9997</td><td>96 ± 5</td><td>1.20</td><td>0.9998</td><td>66 ± 23</td><td>0-0</td><td>0</td></tr><tr><td>Dinotefuran</td><td>0.10</td><td>0.9979</td><td>61 ± 4</td><td>0.23</td><td>0.9984</td><td>77 ± 10</td><td>0.12</td><td>0.9986</td><td>43 ± 56</td><td>0-0</td><td>0</td></tr><tr><td>Fenpropimorph</td><td>0.06</td><td>0.9987</td><td>59 ± 58</td><td>0.08</td><td>0.9983</td><td>66 ± 60</td><td>0.36</td><td>0.9973</td><td>0 ± 0</td><td>0.9-2.5</td><td>26</td></tr><tr><td>Gabapentine</td><td>1.14</td><td>0.9979</td><td>29 ± 30</td><td>0.36</td><td>0.9975</td><td>87 ± 7</td><td>0.70</td><td>0.9980</td><td>96 ± 6</td><td>0-0</td><td>0</td></tr><tr><td>Imidacloprid</td><td>0.14</td><td>0.9985</td><td>82 ± 6</td><td>0.13</td><td>0.9989</td><td>91 ± 6</td><td>0.08</td><td>0.9986</td><td>89 ± 6</td><td>0-0</td><td>0</td></tr><tr><td>Imidacloprid-desnitro</td><td>0.12</td><td>0.9994</td><td>77 ± 24</td><td>0.45</td><td>0.9983</td><td>64 ± 17</td><td>0.33</td><td>0.9915</td><td>91 ± 5</td><td>0-0</td><td>0</td></tr><tr><td>Imidacloprid-olefin</td><td>2.01</td><td>0.9940</td><td>84 ± 6</td><td>0.27</td><td>0.9989</td><td>95 ± 6</td><td>0.91</td><td>0.9965</td><td>83 ± 11</td><td>0-0</td><td>0</td></tr><tr><td>Ioxynil</td><td>0.01</td><td>0.9999</td><td>79 ± 4</td><td>0.01</td><td>0.9976</td><td>75 ± 14</td><td>0.01</td><td>0.9959</td><td>82 ± 22</td><td>0-0</td><td>0</td></tr><tr><td>Melamine</td><td>0.02</td><td>0.9993</td><td>0 ± 0</td><td>0.31</td><td>0.9991</td><td>52 ± 66</td><td>0.18</td><td>0.9963</td><td>99 ± 2</td><td>0-0.4</td><td>11</td></tr><tr><td>Metformin</td><td>0.01</td><td>0.9996</td><td>9 ± 170</td><td>0.68</td><td>0.9968</td><td>80 ± 9</td><td>0.01</td><td>0.9991</td><td>100 ± 0</td><td>0-0</td><td>0</td></tr><tr><td>Metolachlor</td><td>0.01</td><td>0.9988</td><td>85 ± 14</td><td>0.21</td><td>0.9993</td><td>92 ± 6</td><td>0.01</td><td>0.9994</td><td>93 ± 6</td><td>0.6-0.8</td><td>11</td></tr><tr><td>N,N-dimethylsulfamide</td><td>2.22</td><td>0.9983</td><td>29 ± 46</td><td>1.54</td><td>0.9955</td><td>68 ± 15</td><td>1.94</td><td>0.9991</td><td>3 ± 204</td><td>0-0</td><td>0</td></tr><tr><td>N-cyclohexylsulfamate</td><td>0.81</td><td>0.9958</td><td>16 ± 62</td><td>0.56</td><td>0.9960</td><td>91 ± 3</td><td>1.16</td><td>0.9974</td><td>12 ± 123</td><td>0-0</td><td>0</td></tr><tr><td>Nitrosomorpholine</td><td>3.11</td><td>0.9966</td><td>0 ± 0</td><td>1.32</td><td>0.9969</td><td>40 ± 94</td><td>3.56</td><td>0.9966</td><td>70 ± 35</td><td>0-0</td><td>0</td></tr><tr><td>Omethoate</td><td>0.63</td><td>0.9994</td><td>7 ± 110</td><td>0.34</td><td>0.9953</td><td>100 ± 0</td><td>0.16</td><td>0.9956</td><td>79 ± 29</td><td>1-5.4</td><td>15</td></tr><tr><td>Oseltamivir</td><td>0.06</td><td>0.9995</td><td>78 ± 13</td><td>0.15</td><td>0.9940</td><td>96 ± 6</td><td>0.26</td><td>0.9959</td><td>87 ± 5</td><td>0-0</td><td>0</td></tr><tr><td>Oxybenzone</td><td>0.37</td><td>0.9983</td><td>95 ± 15</td><td>0.97</td><td>0.9998</td><td>99 ± 3</td><td>0.60</td><td>0.9964</td><td>0 ± 0</td><td>0.1-2</td><td>44</td></tr><tr><td>Prosulfocarb</td><td>0.09</td><td>0.9987</td><td>83 ± 22</td><td>0.23</td><td>0.9993</td><td>96 ± 5</td><td>0.12</td><td>0.9986</td><td>0 ± 0</td><td>0.3-2.2</td><td>78</td></tr><tr><td>Prosulfuron</td><td>0.12</td><td>0.9976</td><td>90 ± 4</td><td>0.11</td><td>0.9994</td><td>99 ± 1</td><td>0.20</td><td>0.9983</td><td>94 ± 4</td><td>0-0</td><td>0</td></tr><tr><td>Quadrol</td><td>0.01</td><td>0.9996</td><td>90 ± 9</td><td>0.27</td><td>0.9993</td><td>28 ± 77</td><td>0.01</td><td>0.9997</td><td>99 ± 2</td><td>0.1-0.1</td><td>4</td></tr><tr><td>Saccharin</td><td>0.04</td><td>0.9986</td><td>67 ± 12</td><td>0.08</td><td>0.9984</td><td>26 ± 60</td><td>0.31</td><td>0.9956</td><td>55 ± 28</td><td>0.1-0.2</td><td>22</td></tr><tr><td>Sitagliptin</td><td>0.02</td><td>0.9998</td><td>77 ± 17</td><td>0.16</td><td>0.9968</td><td>67 ± 20</td><td>0.31</td><td>0.9958</td><td>96 ± 4</td><td>0-0</td><td>0</td></tr><tr><td>Sulfadiazine</td><td>0.02</td><td>0.9998</td><td>69 ± 10</td><td>0.14</td><td>0.9980</td><td>72 ± 15</td><td>0.08</td><td>0.9973</td><td>100 ± 0</td><td>0.4-0.4</td><td>4</td></tr><tr><td>Sulpiride</td><td>0.01</td><td>0.9995</td><td>61 ± 16</td><td>0.01</td><td>0.9981</td><td>48 ± 21</td><td>0.04</td><td>0.9975</td><td>87 ± 7</td><td>0-0</td><td>0</td></tr><tr><td>Terbutryn</td><td>0.08</td><td>0.9990</td><td>97 ± 2</td><td>0.11</td><td>0.9987</td><td>97 ± 4</td><td>0.14</td><td>0.9997</td><td>99 ± 1</td><td>0.1-0.6</td><td>41</td></tr><tr><td>Theobromine</td><td>0.36</td><td>0.9985</td><td>4 ± 208</td><td>1.17</td><td>0.9982</td><td>53 ± 27</td><td>2.81</td><td>0.9958</td><td>53 ± 47</td><td>0-0</td><td>0</td></tr></tbody></table>

on all phases), highlighting the intrinsic limitations of the current configuration. HLB was the most versatile phase, with 31 compounds above 20% recovery, including 13 sampled exclusively by HLB. SAX recovered 16 compounds, 3 of which were unique to this phase, while SCX recovered 20 compounds, including 3 sampled exclusively by SCX. Fig. 3 presents a Venn diagram of compounds with recoveries > 20%, clearly illustrating the overlap and complementarity of the three sorbents and supporting the need to combine HLB, SAX and SCX to achieve broader and more representative coverage of PMOCs.

## 3.6. Field sampling

### 3.6.1. Treatment efficiency

To address the lack of monitoring data on Persistent and Mobile Organic Contaminants (PMOCs) in drinking water systems, passive sampling campaigns were conducted at seven DWTPs across France. Both RW and TW were analyzed to evaluate the performance of multi-sorbent solid-phase samplers under real-world environmental

conditions, where occurrence data remain scarce [44]. Raw results are provided in Table SI 8–10. Since the flow rates experienced by the passive samplers were of the same order of magnitude, the accumulated quantities can be directly compared except for the RW flow rates at site 4 that were three times lower than at the other sites (technical problem).

Of the 47 monitored compounds, 37 were detected (26 with HLB, 17 with SAX, and 10 with SCX) including 20 classified as highly polar (logP <1). The most frequently detected contaminants included theobromine (85%), saccharin (63%), clothianidin (49%), N-cyclohexylsulfamate (44%), and DEA-OH (40%), confirming the widespread occurrence of anthropogenic compounds consistent with previous studies [11,26,30, 56–58]. The UpSet diagram (Fig. 4) summarizes the distribution of detected compounds among the HLB, SAX, and SCX sorbents for RW and TW samples. Vertical bars represent the number of compounds shared between different extraction conditions (sorbent × water type), while connected dots indicate the specific combinations involved. Horizontal bars show the total number of compounds detected for each individual set. RW samples exhibited a higher number of detected compounds and

<footnote n="1">¹: dimethachlor metabolite CGA-369873; ²: desetylatrazine; ³: desetylatrazine-2-hydroxy; ⁴: desethyl deisopropylatrazine; ⁵: dimethenamid oxanilic acid</footnote>

<footnote>DF: detection frequency</footnote>
<figure><img src="image_7.png" /><figcaption>Fig. 3. Venn diagram illustrating the sampling capacities of HLB, SAX, and SCX sorbents. Only compounds with recoveries greater than 20 % were included.</figcaption></figure>

intersections between sorbents (n = 9) than TW samples (n = 4), reflecting greater chemical diversity and complexity in environmental matrices.

Contamination levels were systematically higher in RW than in TW, both in terms of the number of compounds and total concentrations (Figure SI 5). Total accumulated mass ranged from 4.2 to 1 992.8 ng. disk⁻¹ in RW and from 2.1 to 492.0 ng.disk⁻¹ in TW, with average totals of 597.1 and 116.7 ng.disk⁻¹ respectively. Across all sites and sorbents, the mean reduction factor was approximately 13. Active substances generally exhibited higher accumulated levels than their transformation products (TPs). While the number of detected parent compounds typically decreased after treatment, the number of TPs remained stable or

increased, likely due to degradation of parent compounds into the studied transformation products. However, given the limited coverage of both parent compounds and their TPs, this trend remains difficult to quantify precisely in our study context. Treatments based on activated carbon, filtration and chlorination are efficient to remove contamination but with a certain variability depending on the complexity of the treatment chain considered, that is consistent with previous studies [56]. It is noteworthy that simple chlorination, as applied at Site 1, appeared quite ineffective for contaminant removal and tended to generate additional TPs without fully eliminating the initial substances, that have already been pointed out by other studies [27,56].

A relationship was observed between compound polarity and treatment efficiency. Among three abatement categories (non-removed: <-10 %, stable: -10 % to +10 %, and removed: >10 %) compounds with logP < 1 represented 82 %, 50 %, and 38 %, respectively. This trend aligns with the nature of the applied treatments, primarily based on activated carbon filtration, which preferentially retains more hydrophobic compounds [27,56]. Consequently, highly polar contaminants tend to pass through treatment processes more efficiently, making drinking water a potential vector of human exposure [56,59]. However, removal is a step-dependent and compound-specific, non-linear process. A more mechanistic understanding is required to determine which treatment steps affect which compounds, particularly for polar substances, for which information remains scarce [27].

### 3.6.2. Feedback on the passive sampler

The UpSet diagram (Fig. 4) also provides insight into the behaviour of the different sorbents under field conditions. The largest intersections corresponded to compounds detected in both RW and TW with SAX (n = 6) and those shared between SAX and HLB (n = 5). Overall, SAX exhibited the broadest detection coverage and highest specificity in field samples, whereas HLB had shown superior extraction efficiency under controlled laboratory conditions. This discrepancy likely reflects matrix

<figure><img src="image_8.png" /><figcaption>Fig. 4. Venn diagrams and upset diagram showing the contamination profile of passive samplers exposed to raw water (RW) and treated water (TW) from French drinking water treatment plants, considering the nature of the sorbent.</figcaption></figure>
effects, as natural organic matter in environmental waters can modify compound-sorbent interactions compared to synthetic matrices used during laboratory calibration [47].

Across all samples, 20 of the 33 detected compounds (54 %) were recovered by at least two sorbents, while 9 were unique to SAX, 2 to HLB, and 2 to SCX. This distribution emphasizes the complementary nature of the three phases and supports the combined use of mixed sorbent systems for comprehensive contaminant profiling. SAX yielded the highest detection frequencies and concentrations for anionic compounds such as acesulfame, dimethachlor metabolite CGA-369873, N-cyclohexylsulfamate, diclofenac, dimethenamid-OXA, prosulfuron, and saccharin, as well as for the amphoteric compound 5-fluorocytosine. In contrast, SAX was less effective for acephate and oxybenzone, which were more frequently detected with HLB. This may be explained by their acidic pKa values (8.4 and 7.1, respectively), placing them in a pH range where both neutral and anionic forms coexist. While the efficient retention of bentazon by HLB is well documented [38], its limited recovery with SAX remains unexpected given its anionic character at environmental pH. SCX effectively retained several cationic substances, but clothianidin, fenpropimorph, nitrosomorpholine, and oseltamivir were better captured with HLB or SAX.

Among the detected substances, the most polar compounds were chlormequat (log P = -3.5), metformin (-1.8), and melamine (-1.4). While metformin and melamine have previously been reported in tap water at average concentrations of 26 and 33 ng L⁻¹, respectively [60, 61], data on chlormequat remain extremely limited, reflecting both a monitoring gap and the analytical challenges posed by highly polar compounds. In contrast, the sampler also retained more hydrophobic contaminants, such as oxybenzone (log P = 3.8) and prosulfocarb (log P = 4.5), previously reported in surface waters at concentrations up to 379 and ~20 ng L⁻¹, respectively [62,63]. This wide polarity range highlights the strong potential of the developed sampler to address chemical diversity and improve the representativeness of contaminant characterization in drinking water systems.

## 4. Conclusion

This study presents a novel passive sampling approach specifically designed to improve the detection of Persistent and Mobile Organic Contaminants (PMOCs), with a particular focus on very polar compounds that are largely overlooked in routine drinking water monitoring. By combining three complementary sorbents (HLB, SAX, and SCX) the device offers broad polarity coverage and enhanced retention of highly polar compounds. Laboratory validation demonstrated its robustness against pH variations and confirmed its ability to lower detection limits through time-integrated sampling. Field deployment at seven drinking water treatment plants led to the successful detection of 37 contaminants, including 20 very polar compounds, in both raw and treated waters. While conventional treatment processes achieve substantial contaminant removal, very polar compounds still pass through, highlighting a potential health risk and the need for targeted monitoring strategies. This passive sampler provides a more representative picture of contamination by capturing transient pollution events, and holds strong potential for untargeted screening of emerging contaminants when coupled with high-resolution mass spectrometry.

### CRediT authorship contribution statement

**Vincent Dufour:** Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Project administration, Validation, Visualization, Writing – original draft, Writing – review & editing.
**Guilhem Zerbini:** Conceptualization, Investigation, Visualization, Writing – original draft, Writing – review & editing.
**Laure Wiest:** Conceptualization, Visualization, Writing – review & editing.
**Aurélie Fildier:** Conceptualization, Visualization, Writing – review & editing.
**Xavier Dauchy:** Conceptualization.
**Robert Samuel:** Investigation.
**Jerôme Enault:** Conceptualization.

**Mar Esperanza:** Conceptualization, Writing – review & editing.
**Emmanuelle Vulliet:** Conceptualization, Funding acquisition, Project administration, Resources, Supervision, Writing – review & editing.

### Declaration of Competing Interest

The authors 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

This action is led by the Ministries for Agriculture, Food Sovereignty and Forestry, for ecological Transition, Energy, Climate and Risk Prevention, for Health and Access to Care, and of Higher Education and Research, with the financial support of the French Office for Biodiversity, with the fees for diffuse pollution coming from the Ecophyto II+ - plan - (convention n°OFB.21.0448).

## Appendix A. Supporting information

Supplementary data associated with this article can be found in the online version at doi:10.1016/j.jhazmat.2025.140754.

### Data availability

Data will be made available on request.

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