Development of new polar monolithic coatings for stir bar sorptive extraction.

Polar vinyl monomers have been used for the synthesis of several polymer monoliths, to serve as novel coatings for stir bar sorptive extraction; the monovinyl monomers 2-hydroxyethyl methacrylate (HEMA) and poly(ethylene glycol) monomethacrylate) (PEGMA) were copolymerized with (apolar) divinylbenzene (DVB) and/or pentaerythritol triacrylate (PETRA), both of which are cross-linking agents. After the optimization of the most important synthesis parameters, which included the ratio between total monomers and porogen, the nature of the porogen, and the monomer ratios, inter alia, three mechanically stable, polar monolithic coatings for stir bar sorptive extraction were obtained that were based on poly(HEMA-co-DVB), poly(HEMA-co-PETRA), and poly(PEGMA-co-PETRA). Thereafter, and in order to evaluate the hydrophilicity of the resulting monoliths, they were applied as materials in the stir bar sorptive extraction of a group of emerging pollutants with a wide range of polarities. The results showed that both the poly(HEMA-co-DVB) and poly(PEGMA-co-PETRA) materials could be used to extract both polar and nonpolar compounds by stir bar sorptive extraction, in an effective manner. Taking into account the desired chemical and morphological properties, as well as the extraction efficiencies, the poly(PEGMA-co-PETRA) material seemed to be a particularly promising monolith for application as a novel coating in stir bar sorptive extraction.

Evaluation of strong cation-exchange polymers for the determination of drugs by solid-phase extraction-liquid chromatography-tandem mass spectrometry.

This paper presents eight distinct strong cation-exchange resins, all of which were derived from precursor resins that had been synthesised using either precipitation polymerisation or non-aqueous dispersion polymerisation. The precursor resins were transformed into the corresponding strong cation-exchange resins by hypercrosslinking followed by polymer analogous reactions, to yield materials with high specific surface areas and strong cation-exchange character. These novel resins were then evaluated as strong cation-exchange (SCX) sorbents in the solid-phase extraction (SPE) of a group of drugs from aqueous samples. Following preliminary experiments, the two best-performing resins were then evaluated in solid-phase extraction-liquid chromatography-tandem mass spectrometry (SPE/LC-MS/MS) to determine a group of drugs from sewage samples. In general, use of these sorbents led to excellent recovery values (75-100%) for most of the target drugs and negligible matrix effects (ME) (<20% ion suppression/enhancement of the analyte signal), when 50mL and 25mL of effluent and influent sewage water samples, respectively, were percolated through the resins. Finally, a validated method based on SPE/LC-MS/MS was used to quantify the target drugs present in different sewage samples.

Selective determination of pharmaceuticals and illicit drugs in wastewaters using a novel strong cation-exchange solid-phase extraction combined with liquid chromatography-tandem mass spectrometry.

In this study, two materials are presented with strong cation-exchange (SCX) behaviour synthesised by two different approaches and then crushed for their application as sorbents for solid-phase extraction (SPE) to extract a group of pharmaceuticals and illicit drugs selectively from wastewater samples. The first SCX polymer was obtained by copolymerisation of three monomers: 2-acrylamido-2-methylpropane sulphonic acid (AMPSA), 2-hydroxyethyl methacrylate (HEMA) and pentaerythritol triacrylate (PETRA), while the second was obtained by post-modification with sulphuric acid (H2SO4) of a copolymer based on HEMA and divinylbenzene (DVB). After their syntheses, both polymers were evaluated as SPE sorbents, with all parameters affecting SPE being optimised, such as sample pH, washing and elution solvents and volumes. Thanks to the sulphonic groups present in the structure of the polymers, all of the compounds with basic functionalities were retained on the sorbents after the washing step, removing the acidic analytes and other interfering compounds, providing successful results in terms of ion suppression/enhancement (-12% and 21%) when wastewater samples were analysed. However, AMPSA/HEMA/PETRA (20/60/20) failed to retain the analytes after loading wastewater samples (25 or 50mL), decreasing analyte recovery values significantly, whereas the sulphonated HEMA/DVB (50/50) enabled good SPE performance with recovery values between 70% and 98%, except for ranitidine and EDDP (39% and 43%, respectively). Therefore, this polymer was selected for further method validation and quantification of wastewater samples, providing low method detection limits (MDLs) in this matrix (from 2 to 40ngL(-1)). Finally, most of the studied compounds were detected and quantified in wastewater samples, especially atenolol, ranitidine, cocaine and its metabolite benzoylecgonine.

Preparation of a polar monolithic coating for stir bar sorptive extraction of emerging contaminants from wastewaters.

A new polar monolith based on poly(poly(ethylene glycol) methacrylate-co-pentaerythritol triacrylate) (poly(PEGMA-co-PETRA)) was first synthesised, after the optimisation of the polymerisation conditions, and applied as a coating for the stir bar sorptive extraction (SBSE) of a group of pharmaceuticals and personal care products (PPCPs) from environmental water samples. Several parameters affecting extraction and liquid desorption in SBSE were investigated to achieve the optimal sorption efficiencies for the studied analytes. Under the optimised experimental conditions, a rapid, simple and sensitive SBSE performance was provided by the in-house monolithic stir bar. Moreover, the in-house coating was able to extract and desorb most of the studied analytes more effectively and quickly, due to its polar behaviour and suitable mechanical and physical properties, in comparison with the recently commercialised polar stir bars (EG Silicone Twister(®) and Acrylate Twister(®)). The analytical methodology, including SBSE followed by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS), was validated and successfully applied for the determination of a group of PPCPs in wastewater samples.

A rapid determination of acidic pharmaceuticals in environmental waters by molecularly imprinted solid-phase extraction coupled to tandem mass spectrometry without chromatography.

This study presents a rapid analytical method that involves an off-line molecularly imprinted solid-phase extraction (MISPE) specific for non-steroidal anti-inflammatory drugs (NSAIDs) as a selective sample pretreatment coupled directly to tandem mass spectrometry (MS/MS). The developed methodology provided sensitive and selective detection and quantification of six acidic pharmaceuticals in wastewaters without the chromatographic separation. The optimised MISPE procedure enabled to extract effectively the studied analytes from effluent and influent wastewaters with satisfactory recovery values (from 62% to 103%). The analytical method developed was validated using 50 mL of effluent wastewaters, obtaining limits of detection (LODs) lower than 0.1 µg L(-1) for all the compounds studied. The method was successfully applied for the determination of these acidic pharmaceuticals in effluent and influent wastewaters. The analytes and their concentration are in line with other studies in which these analytes are determined by SPE-LC-MS/MS in similar samples.

Novel coatings for stir bar sorptive extraction to determine pharmaceuticals and personal care products in environmental waters by liquid chromatography and tandem mass spectrometry.

Two new commercially available polar coatings for stir bar sorptive extraction (SBSE), consisting of polyacrylate (PA) with a proportion of polyethyleneglycol (PEG) (Acrylate Twister(®)) and PEG modified silicone (EG Silicone Twister(®)), were evaluated and compared with the classic coating based on polydimethylsiloxane (PDMS Twister(®)) for the extraction of a group of pharmaceuticals and personal care products (PPCPs) from wastewater samples. The SBSE parameters, such as sample pH, agitation speed, extraction temperature, extraction time, desorption solvent and time, were optimised in order to achieve suitable sorption of the target analytes. The EG Silicone coating enabled more efficient extraction of some polar compounds as well as improving the sorption of apolar compounds, in comparison with the other two coatings. Finally, the method of SBSE followed by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) using the EG Silicone coating was validated achieving good linearity (r(2)>0.994, except for CBZ (r(2)>0.989)), precision (%RSD<17%) and low limits of quantification (LOQs) (20-40 ng L(-1)). The SBSE/LC-MS/MS methodology was applied for the determination of PPCPs in wastewater samples.

Determination of pharmaceuticals in wastewaters using solid-phase extraction-liquid chromatography-tandem mass spectrometry.

Four different commercial sorbents for solid-phase extraction have been evaluated for the extraction of a group of acidic pharmaceuticals in terms of selectivity and capacity: Oasis hydrophilic-lipophilic balance (HLB), Oasis MAX (strong anion exchange), Oasis WAX (weak anion exchange) and a commercial available molecularly imprinted polymer specific for non-steroidal anti-inflammatory drugs. Among the sorbents studied, molecularly imprinted polymer proved to be very effective in the reduction of matrix interferences and the selective extraction of acidic pharmaceuticals, such as salicylic acid, ibuprofen, fenoprofen, diclofenac and naproxen, among others, from effluent wastewater samples. Moreover, molecularly imprinted solid-phase extraction protocol was applied to liquid chromatography coupled to tandem mass spectrometry (MS/MS) with the purpose of evaluating the clean-up effect on ion suppression/enhancement when the complexity of the samples increases and a reduction of this effect was observed. Molecularly imprinted solid-phase extraction followed by liquid chromatography coupled to ultraviolet detection and liquid chromatography coupled to tandem mass spectrometry validation methodologies with effluent wastewaters were developed, obtaining recoveries between 70 and 85% and limits of detection at low levels of µg/L (0.15-1 µg/L) and ng/L (0.5-2 ng/L), respectively. The final application of molecularly imprinted solid-phase extraction and liquid chromatography coupled to MS/MS detection showed the presence of acidic pharmaceuticals studied in this work in effluent wastewaters (