Development of a maleic acid-based material to selectively solid-phase extract basic compounds from environmental samples.

This study presents a novel mixed-mode weak cation-exchange (WCX) material. This material was prepared by means of the functionalization of a mesoporous divinylbenzene (DVB) resin with maleic acid (maleic acid-DVB), which yielded a high carboxylic moiety content resulting in WCX interactions as well as suitable specific surface area for reversed-phase interactions. After the optimization of the solid-phase extraction (SPE) protocol to enhance the selectivity of the sorbent, this material was evaluated as a novel WCX sorbent in the SPE of a group of drugs from environmental water samples. The method is based on SPE followed by liquid chromatography (LC) coupled to high resolution mass spectrometry (HRMS) with an Orbitrap analyzer, and was validated and applied for the determination of basic drugs in river, effluent and influent wastewater samples. Maleic acid-DVB sorbent yielded suitable recovery rates (57% to 89%) and an acceptable matrix effect (<32%) thanks to the effective washing step included when these environmental waters were loaded through the novel resin. The method was applied to different environmental water samples and some basic drugs were suitably quantified in these environmental samples.

Management actions to mitigate the occurrence of pharmaceuticals in river networks in a global change context.

Human consumption of pharmaceuticals leads to high concentrations of pharmaceuticals in wastewater, which is usually not or insufficiently collected and treated before release into freshwater ecosystems. There, pharmaceuticals may pose a threat to aquatic biota. Unfortunately, occurrence data of pharmaceuticals in freshwaters at the global scale is scarce and unevenly distributed, thus preventing the identification of hotspots, the prediction of the impact of Global Change (particularly streamflow and population changes) on their occurrence, and the design of appropriate mitigation actions. Here, we use diclofenac (DCL) as a typical pharmaceutical contaminant, and a global model of DCL chemical fate based on wastewater sanitation, population density and hydrology to estimate current concentrations in the river network, the impact of future changes in runoff and population, and potential mitigation actions in line with the Sustainable Development Goals. Our model is calibrated against measurements available in the literature. We estimate that 2.74 ± 0.63% of global river network length has DCL concentrations exceeding the proposed EU Watch list limit (100 ng L-1). Furthermore, many rivers downstream from highly populated areas show values beyond 1000 ng L-1, particularly those associated to megacities in Asia lacking sufficient wastewater treatment. This situation will worsen with Global Change, as streamflow changes and human population growth will increase the proportion of the river network above 100 ng L-1 up to 3.10 ± 0.72%. Given this background, we assessed feasible source and end-of-pipe mitigation actions, including per capita consumption reduction through eco-directed sustainable prescribing (EDSP), the implementation of the United Nations Sustainable Development Goal (SDG) 6 of halving the proportion of population without access to safely managed sanitation services, and improvement of wastewater treatment plants up to the Swiss standards. Among the considered end-of-pipe mitigation actions, implementation of SDG 6 was the most effective, reducing the proportion of the river network above 100 ng L-1 down to 2.95 ± 0.68%. However, EDSP brought this proportion down to 2.80 ± 0.64%. Overall, our findings indicate that the sole implementation of technological improvements will be insufficient to prevent the expected increase in pharmaceuticals concentration, and that technological solution need to be combined with source mitigation actions.

Global CO2 emissions from dry inland waters share common drivers across ecosystems.

Many inland waters exhibit complete or partial desiccation, or have vanished due to global change, exposing sediments to the atmosphere. Yet, data on carbon dioxide (CO2) emissions from these sediments are too scarce to upscale emissions for global estimates or to understand their fundamental drivers. Here, we present the results of a global survey covering 196 dry inland waters across diverse ecosystem types and climate zones. We show that their CO2 emissions share fundamental drivers and constitute a substantial fraction of the carbon cycled by inland waters. CO2 emissions were consistent across ecosystem types and climate zones, with local characteristics explaining much of the variability. Accounting for such emissions increases global estimates of carbon emissions from inland waters by 6% (~0.12 Pg C y-1). Our results indicate that emissions from dry inland waters represent a significant and likely increasing component of the inland waters carbon cycle.

Solid-phase extraction followed by liquid chromatography-high resolution mass spectrometry to determine synthetic cathinones in different types of environmental water samples.

Synthetic cathinones have become popular in recent years, which would explain why their determination in influent sewage samples has already been documented. In the present study a method based on solid-phase extraction followed by liquid chromatography and high resolution mass spectrometry is developed, validated and applied to determine twelve cathinones and one of their metabolites in different environmental samples including influent and effluent sewage and river water. Two cation-exchange sorbents (Oasis MCX and Oasis WCX) were compared, with better results achieved with Oasis WCX in terms of apparent recoveries (70-100%) and matrix effects (lower than -34%). The method was validated with effluent sewage samples providing suitable figures of merit, with method quantification limits ranging from 1ng/L to 5ng/L and method detection limits from 0.1ng/L to 0.5ng/L for all the compounds. Of the different cathinones studied, three, namely methylone, mephedrone metabolite and methylenedioxypyrovalerone, were quantified at concentration levels of low ng/L in each of the different samples analysed, while a number of the other cathinones were also detected in some of the samples.

Incorporating model uncertainty into the evaluation of interventions to reduce microcontaminant loads in rivers.

Models of microcontaminant fate and transport in wastewater treatment plants (WWTPs) and rivers have been developed and used to assist decision-making in the field of water management. These models come with parameter uncertainties that must be properly incorporated in the decision-making process. The main goal of this study is to evaluate how the magnitudes of key model parameter uncertainties influence the selection of end-of-pipe interventions (at WWTPs) designed to reduce the microcontaminant loads in rivers. We developed a model that describes the fate and removal of pharmaceuticals in WWTPs and the river network based on 3 key parameters: human pharmaceutical consumption and excretion (F) and the pharmaceutical degradation constants in WWTPs (kWWTP) and rivers (kriver). We modelled the fate and transport of diclofenac in the Llobregat River basin (NE Spain). We calibrated the model using a Bayesian approach, which resulted in an accurate prediction of measured diclofenac loads at 9 locations along the Llobregat River and at the influents and effluents of 2 WWTPs (R2 = 0.95). Using different scenarios, we evaluated three levels of uncertainty in the key model parameters. The first level of uncertainty corresponded to the reference distributions obtained from the Bayesian calibration. Then, for each parameter, we generated a narrower PDF (decreased uncertainty with respect to the reference) and a wider PDF (increased uncertainty). For each level of uncertainty, we evaluated increasing removal efficiencies of diclofenac at the WWTPs, from 38% to 98%. We assumed that removal efficiencies of up to 75% can be achieved by upgrading secondary treatment; beyond 75%, tertiary treatment is needed. The scenario analysis showed that achieving diclofenac removal efficiencies corresponding to tertiary treatment results in apparent concentration reductions (statistically significant differences relative to the reference situation), regardless of the level of uncertainty applied to the model parameters. However, upgrades in the secondary treatment resulted in apparent reductions only in the case of reduced uncertainty. We concluded that model uncertainty greatly influences the decisions that river basin authorities must make to reduce the microcontaminant loads released by WWTPs into rivers. In addition, we discussed research priorities to help reduce model uncertainty and thereby make more appropriate decisions.

Comparison of triple quadrupole mass spectrometry and Orbitrap high-resolution mass spectrometry in ultrahigh performance liquid chromatography for the determination of veterinary drugs in sewage: benefits and drawbacks.

This paper presents a comparison of triple quadrupole tandem mass spectrometry (MS/MS) and Orbitrap high-resolution mass spectrometry (HRMS) combined to ultrahigh performance liquid chromatography for the determination of glucocorticoids and polyether ionophores in sewage, in order to show the major benefits and drawbacks for each mass spectrometry analyser. Overall, HRMS measurements have enhanced performance in terms of confirmatory capabilities than MS/MS measurements. Moreover, similar limits of quantification, limits of detection, linear range and repeatability for glucocorticoids with both the MS/MS and HRMS methods were compared, but in the case of polyether ionophores, slightly better limits of detection and limits of quantification were obtained with the HRMS method because of the high sensitivity obtained when diagnostic ions are used for quantification instead of selected reaction monitoring transitions for these compounds. The two methods have been applied to the analysis of several influent and effluent sewage samples from sewage treatment plants located in the Tarragona region (Catalonia, Spain), showing an excellent correlation between the two methods.

A pressurised hot water extraction and liquid chromatography-high resolution mass spectrometry method to determine polar benzotriazole, benzothiazole and benzenesulfonamide derivates in sewage sludge.

Benzothiazole, benzotriazole and benzenesulfonamide derivates are well-known aquatic contaminants, although very few studies have been published about their occurrence in sewage sludge samples. In this paper, a pressurised hot water extraction (PHWE) method has been developed for the simultaneous determination of these families of compounds. The compounds were determined by LC-Orbitrap-HRMS and several clean-up strategies such as in-cell PHWE and solid-phase extraction (SPE) were tested to reduce the high matrix effect that occurs when sludge samples are analysed. Absolute recoveries using the whole method were above 80% and the matrix effect was under -20% for most of the compounds studied. Repeatability and reproducibility were usually under 10% (%RSD, 50 and 250ngg(-1) (d.w.), n=5), while LODs and LOQs were between 0.25 and 25ngg(-1) (d.w.) and 0.5 and 50ngg(-1) (d.w.), respectively. The PHWE/SPE/LC-HRMS method developed was used to analyse several sludge samples collected from five sewage treatment plants (STPs) in Catalonia that use different sewage treatments. The most frequently determined compounds were benzotriazole derivates and the most abundant compound found was 2-hydroxybenzothiazole.

Determination of N-nitrosamines and nicotine in air particulate matter samples by pressurised liquid extraction and gas chromatography-ion trap tandem mass spectrometry.

N-nitrosamines are potentially hazardous pollutants, classified as probable carcinogenic and mutagenic by the U.S. Environmental Protection Agency (EPA). In this paper, the presence of these pollutants was studied in air samples taken at different locations of Tarragona (urban and harbour). As a result, a reliable method has been developed for determining N-nitrosamines and nicotine based on pressurised liquid extraction (PLE) and gas chromatography-(chemical ionisation) ion trap tandem mass spectrometry (GC-(CI)MS/MS). The chromatographic analysis enables the determination of these compounds in less than 13 min with total separation and good resolution between the compounds. Recovery values were higher than 80% for most of the compounds and the repeatability of the method was under 18% (5 ng m(-3), %RSD, n=4). MDLs were between 0.1 ng m(-3) (NMor and NPip) and 2 ng m(-3) (NMEA). NMor, NPyr, NPip and nicotine were the most frequent compounds in urban and harbour samples at concentration levels between 0.3 ng m(-3) (NPyr) and 12.5 ng m(-3) (nicotine) and between 0.13 ng m(-3) (NPyr) and 3.8 ng m(-3) (nicotine), respectively.

Efficient tandem solid-phase extraction and liquid chromatography-triple quadrupole mass spectrometry method to determine polar benzotriazole, benzothiazole and benzenesulfonamide contaminants in environmental water samples.

An analytical method has been developed that allows the simultaneous determination of five benzotriazole (BTRs), four benzothiazole (BTs) and five benzenesulfonamide (BSAs) derivates. The method is based on tandem solid-phase extraction (SPE) with Oasis HLB followed by a clean-up step with Florisil. The chromatographic analysis was performed in less than 15min and detection was carried out with a triple quadrupole mass analyser operating in multiple reaction monitoring (MRM) mode. A comparison was performed between Oasis HLB and Oasis MAX sorbents for the solid-phase extraction, with Oasis HLB being the sorbent that gave the highest recoveries, ranging between 75% and 106%, depending on the compound and the matrix analysed. The proposed clean-up with Florisil sorbent reduced the matrix effect to below 20%. The repeatability (%RSD, 50-3000ng/L, n=3) of the method was less than 15% for all of the compounds in all of the matrices. The limits of detection (LODs) achieved ranged from 1ng/L for BTR in river water up to 100ng/L for BT in influent sewage. All of the compounds were determined in environmental waters such as river water and sewage. The highest concentrations determined corresponded to influent sewage samples in which the sum of concentrations for all compounds were between 4.6µg/L and 8.0µg/L. These concentrations were slightly reduced in secondary effluent and tertiary effluent sewage. Moreover, samples from tertiary effluent sewage based on ultra-filtration membrane treatments were also analysed and preliminary results seem to indicate that these treatments may be most effective for removing BTR, BT and BSA derivates.

Thermal desorption-gas chromatography-mass spectrometry method to determine phthalate and organophosphate esters from air samples.

A method based on thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) has been developed to determine four organophosphate esters, seven phthalate esters, and bis(2-ethylhexyl) adipate in the gas phase from harbour and urban air samples. The method involves the sampling of 1.5L of air in a Tenax TA sorbent tube followed by thermal desorption (using a Tenax TA cryogenic trap) coupled to gas chromatography-mass spectrometry. The repeatability of the method expressed as %RSD (n=3) is less than 15% and the MQLs are between 0.007µgm(-3) (DMP, TBP, BBP, TPP and DnOP) and 6.7µgm(-3) (DEHP). The method was successfully applied in two areas (urban and harbour) testing two and three points in each one, respectively. Some of these compounds were found in both urban and harbour samples. Di-(2-ethylhexyl)phthalate was the most abundant compound found in both areas at concentration levels between 6.7µgm(-3) and 136.4µgm(-3). This study demonstrates that thermal desorption is an efficient method for the determination of these semi-volatile compounds in the gas phase fraction of air samples.

Determination of polyether ionophores in urban sewage sludge by pressurised liquid extraction and liquid chromatography-tandem mass spectrometry: study of different clean-up strategies.

A method for the determination of five polyether ionophores in urban sewage sludge has been developed. The extraction of compounds was performed by pressurised liquid extraction using acetone, while florisil was used for in-cell clean-up to minimise the matrix effect in the sludge extracts. An amide polar-embedded reversed-phase column was used for the chromatographic separation with a rapid-resolution liquid chromatograph coupled to a tandem mass spectrometer. Moreover, several clean-up strategies such as in-cell and on-cell clean-up and solid-phase extraction clean-up, among others, were tested and their results are discussed in the present paper. Recoveries (10 and 250 µg/kg in dry weight (d.w.), n=6) were close to 90%, repeatability and reproducibility (%RSD, 10 and 250 µg/kg (d.w.), n=6) were less than 10% and 12%, respectively. Limits of detection (LODs) and limits of quantification (LOQs) ranged between 0.5 and 1 µg/kg (d.w.) and between 1 and 5 µg/kg (d.w.), respectively. The method was applied to samples collected in five sewage treatment plants in Catalonia. Monensin and narasin were determined in some sludge samples at concentrations from

Pressurised liquid extraction and ultra-high performance liquid chromatography-tandem mass spectrometry to determine endogenous and synthetic glucocorticoids in sewage sludge.

Glucocorticoids are a type of steroid hormones classified as endocrine disrupting chemicals (EDCs) and they are widely used by human and animal medicine. In this paper, we describe the development and validation of an analytical method for the determination of 9 selected glucocorticoids (betamethasone, cortisol (hydrocortisone), cortisone, dexamethasone, flumethasone, methylprednisolone, prednisolone, prednisone and triamcinolone acetonide) in sewage sludge by pressurised liquid extraction (PLE) and ultra-high performance liquid chromatography with tandem mass spectrometry (UHPLC-MS/MS). PLE with on-cell clean-up followed by solid-phase extraction (SPE) clean-up (Oasis HLB) has been applied to extract the analytes and clean up the matrix. Recoveries of the method were from 8% for prednisone and cortisone to 73% for triamcinolone acetonide. The developed method achieves limits of detection (LODs) between 1 and 5 µg/Kg dry weight (d.w.) in sludge and the repeatability expressed as relative standard deviation (%RSD, 50 µg/Kg (d.w.), n=3) is less than 8%. The PLE/SPE/UHPLC-MS/MS method was successfully applied to determine these pollutants in sludge samples from two sewage treatment plants located in the Tarragona area. Cortisone was found at levels below LOQ, cortisol between 5.2 and 6.1 µg/Kg (d.w.) and prednisolone between

Determination of phthalates and organophosphate esters in particulated material from harbour air samples by pressurised liquid extraction and gas chromatography-mass spectrometry.

A method based on gas chromatography-mass spectrometry (GC-MS) combined with a pressurised liquid extraction (PLE) to determine four organophosphates, seven phthalate esters and bis(2-ethylhexyl) adipate in particulated material of harbour air samples has been developed. Some studies show that these compounds may cause hormone disrupting effects on human health. Moreover, the U.S. Environmental Protection Agency (EPA) has classified benzyl butyl phthalate and di(2-ethylhexyl) phthalate as possible human carcinogens.The chromatographic time per run analysis is less than 15 min and the complete separation of all compounds is achieved. The PLE was optimised with recoveries above 90% and the repeatability of the method with real samples is less than 11% (%RSD, n=4). The MDLs (0.004-0.4 ng m(-3)) and MQLs (0.02-2 ng m(-3)) are limited by the fact of some compounds are present in low levels in sampling blank filters.The method was successfully applied in several samples and most of the compounds under study were found. The most relevant values were the high concentration of di-iso-butyl phthalate (between 28 and 529 ng m(-3)) and the significant concentration of di(2-ethylhexyl) phthalate (between MQL and 22 ng m(-3)). In addition, benzyl butyl phthalate was also detected in some samples but at low concentration levels (between MQL to 0.2 ng m(-3)).

Novel amide polar-embedded reversed-phase column for the fast liquid chromatography-tandem mass spectrometry method to determine polyether ionophores in environmental waters.

A fast chromatographic method has been developed that takes less than 5 min per run to determine five polyether ionophores with a novel amide polar-embedded reversed-phase column coupled to a triple quadrupole mass spectrometer. A comparison between Oasis HLB and Oasis MAX sorbents for the solid-phase extraction was done. Oasis HLB sorbent gave recoveries close to 90% and the repeatability (%RSD, 25-100 ng/L, n=3) of the method was less than 7% for all compounds in all matrices. The presence of polyether ionophores in environmental waters such as river water and sewage was investigated. Monensin and narasin were frequently determined in influent and effluent sewage at concentrations from 10 ng/L to 47 ng/L in influents and from 6 ng/L to 34 ng/L in effluents. In river waters, polyether ionophores were not detected in any sample.

Determination of glucocorticoids in sewage and river waters by ultra-high performance liquid chromatography-tandem mass spectrometry.

In this paper we present a method based on ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) combined with a solid-phase extraction to determine nine glucocorticoids in river waters and sewage. In addition, we attempt the chromatographic separation of two glucocorticoid epimers (betamethasone and dexamethasone) which until now had not been determined simultaneously in environmental matrices. For SPE, we have tested three commercial polymeric polar/non-polar balanced sorbents. The recoveries were close to or above 90% in rivers and sewage influents and effluents. The repeatability expressed as relative standard deviation (%RSD, n=3, 10 ng/L) was less than 8% in all cases. The method obtains LODs for glucocorticoids at low ng/L levels in aqueous environmental matrices (0.5-20 ng/L depending on the matrix and the analyte). The method was applied to determine these compounds in three Catalan rivers (Ebre, Ter and LLobregat) and two sewage treatment plants in the Tarragona area. Cortisone, cortisol, prednisone and prednisolone were frequently determined in influent sewage samples between 21 and 285 ng/L. Moreover, the two epimers were successfully determined below LOQs in some influent sewage samples.

Preparation of a polar monolithic stir bar based on methacrylic acid and divinylbenzene for the sorptive extraction of polar pharmaceuticals from complex water samples.

A monolithic, hydrophilic stir bar coating based upon a copolymer of methacrylic acid and divinylbenzene [poly(MAA-co-DVB)] was synthesised and evaluated as a new polymeric phase for the stir bar sorptive extraction (SBSE) of polar compounds from complex environmental water samples. The experimental conditions for the extraction and liquid desorption in SBSE were optimised. Liquid chromatography-triple quadrupole mass spectrometry (LC-MS/MS) was used for the determination of a group of polar pharmaceuticals in environmental water matrices. The extraction performance of the poly(MAA-co-DVB) stir bar was compared to the extraction performance of a commercially available polydimethylsiloxane stir bar; it was found that the former gave rise to significantly higher extraction efficiency of polar analytes (% recovery values near to 100% for most of the studied analytes) than the commercial product. The developed method was applied to determine the studied analytes at low ng L⁻¹ in different complex environmental water samples.

Development and application of a polar coating for stir bar sorptive extraction of emerging pollutants from environmental water samples.

In the present study, a stir bar coated with hydrophilic polymer based on poly(N-vinylpyrrolidone-co-divinylbenzene) was prepared for the sorptive extraction of polar compounds. The main parameters affecting the polymerisation of the coating were investigated. The new stir bar was applied successfully in stir bar sorptive extraction with liquid desorption followed by liquid chromatography-mass spectrometry in tandem with a triple quadrupole for the determination of a group of polar pharmaceuticals and personal care products (PPCPs) in environmental water matrices. Different variables affecting extraction and desorption such as agitation speed, temperature, ionic strength and extraction time were optimised. The results showed that the stir bar is able to enrich the selected analytes effectively. The developed method was applied to determine a group of PPCPs in different complex environmental samples, including river, effluent and influent waste water.

Molecularly imprinted polymer with high-fidelity binding sites for the selective extraction of barbiturates from human urine.

In this paper we describe the synthesis of a molecularly imprinted polymer (MIP) by precipitation polymerisation, with barbital as the template molecule, and the application of the barbital MIP as a molecularly selective sorbent in the solid-phase extraction (SPE) of barbiturates from human urine samples. The MIP was synthesised by precipitation polymerisation using 2,6-bis-acrylamidopyridine as the functional monomer and DVB-80 as the cross-linking agent. The spherical MIP particles produced were 4.2 ± 0.4 µm in diameter; a non-imprinted control polymer (NIP) in bead form was 4.8 ± 0.4 µm (mean±standard deviation) in diameter. The particles were packed into a solid-phase extraction cartridge and employed as a novel sorbent in a molecularly imprinted solid-phase extraction (MISPE) protocol. The MIP showed high selectivity for the template molecule, barbital, a feature which can be ascribed to the high-fidelity binding sites present in the MIP which arose from the use of 2,6-bis-acrylamidopyridine as the functional monomer. However, the MIP also displayed useful cross-selectivity for other barbiturates besides barbital. For real samples, the MIP was applied for the extraction of four barbiturates from human urine. However, due to the high urea concentration in this sample which interfere the proper interaction of barbiturates onto the MIP, a tandem system using a commercially available sorbent was developed.

Synthetic approaches to parabens molecularly imprinted polymers and their applications to the solid-phase extraction of river water samples.

In this paper we describe the synthesis, characterisation and use of two distinct molecularly imprinted polymers (MIPs) prepared using esters of p-hydroxybenzoic acid (parabens) as templates: one MIP was synthesised by precipitation polymerisation using a semi-covalent molecularly imprinting strategy with methyl paraben as the template/target (MIP 1); the second MIP was prepared in monolithic form through a conventional non-covalent molecular imprinting strategy, with butyl paraben as the template (MIP 2). MIP 1 recognized methyl paraben, showed cross-selectivity for other parabens analytes used in the study and higher affinity towards these compounds than did a non-imprinted control polymer. Similarly, MIP 2 demonstrated higher affinity towards paraben analytes than a non-imprinted control polymer. For the analysis of environmental water samples, a solid-phase extraction (SPE) protocol was developed using MIP 2 as sorbent, and results were compared to a SPE using a commercial sorbent (Oasis HLB). With MIP 2 as sorbent and butyl paraben as target, when percolating 500 mL of river water spiked at 1 µg L(-1) through the SPE cartridge, and using 1 mL of isopropanol as cleaning solvent, a higher recovery of butyl 4-hydroxybenzoate (butyl paraben) and a cleaner chromatogram where achievable when using the MIP compared to the commercial sorbent.

Synthesis and application of hypercrosslinked polymers with weak cation-exchange character for the selective extraction of basic pharmaceuticals from complex environmental water samples.

The synthesis of high specific surface area sorbents (HXLPP-WCX) in the form of hypercrosslinked polymer microspheres with narrow particle size distributions, average particle diameters around 6 microm, and weak cation-exchange (WCX) character, is described. The WCX character arises from carboxylic acid moieties in the polymers, derived from the comonomer methacrylic acid. A novel HXLPP-WCX sorbent with an attractive set of chemical and physical properties was then used in an off-line solid-phase extraction (SPE) protocol for the selective extraction of a group of basic compounds from complex environmental samples, a priority being the clean separation of the basic compounds of interest from acidic compounds and interferences. The separation power of the new sorbent for basic pharmaceuticals was compared to two commercially available, mixed-mode sorbents, namely Oasis WCX and Strata-X-CW. Under identical experimental conditions, HXLPP-WCX was found to deliver both higher capacity and better selectivity in SPE than either of the two commercially available materials. In an optimised SPE protocol, the HXLPP-WCX sorbent gave rise to quantitative and selective extractions of low microg l(-1) levels of basic pharmaceuticals present in 500 ml of river water and 250 ml of effluent waste water.