In-field determination of nanomolar nitrite in seawater using a sequential injection technique combined with solid phase enrichment and colorimetric detection

A novel sequential injection method for the determination of nitrite at nanomolar level in seawater samples has been developed. The pink azo compound was formed based on the Griess reaction and quantitatively adsorbed onto a Sep-Pak C18 cartridge. The enriched azo compound was rinsed with water and ethanol (28%, v/v) in turn, and then eluted with an eluent containing 26.6% (v/v) ethanol and 0.108 mol L⁻¹ H₂SO₄. Finally the azo compound was measured using a spectrophotometer at 543 nm. Under the optimized conditions, the linear calibration ranges were 0.71–42.9 nmol L⁻¹ for a 150-mL sample and 35.7–429 nmol L⁻¹ for a 15-mL sample. The relative standard deviation of 8 measurements was 1.44% for 14.3 nmol L⁻¹ nitrite. For the 150 mL sample, the detection limit was estimated to be 0.1 nmol L⁻¹. The throughput of the method was about 4 samples per hour. The proposed method has been successfully applied to the in-field determination of nanomolar concentrations of nitrite in seawater.     

Determination of iron and copper in seawater at pH 1.7 with a new commercially available chelating resin, NTA Superflow

The use of a commercially available chelating resin with NTA-type functional groups for concentration of trace metals from seawater is described. Trace metal recoveries from this NTA Superflow chelating resin are pH dependent. At a pH of ≤2 only iron(III) and copper are quantitatively recovered from the resin. Iron(II) cannot be quantitatively recovered from this resin below a pH of 5. However, oxidation of acidified seawater samples (pH 1.7) with H₂O₂ prior to loading onto the resin has been demonstrated to allow quantitative recovery of total dissolved iron. Deferrioxamine and Rhodoturlic Acid, two commercially available siderophores were used to investigate the effect of strong Fe(III)-binding organic ligands on the ability to retain iron at different pH values. Acidification of seawater samples to pH 1.7 dissociates the iron complexed to these organic ligands, thereby allowing total dissolved iron and copper to be determined. Acidified samples from Monterey Bay were analyzed by a flow injection method coupled to ICP-SFMS detection using the NTA Superflow resin in the pre-concentration step. Results from this study show that when seawater samples are stored acidified (pH 1.7) over time, a portion of iron(III) is reduced to iron(II), thus necessitating the use of H₂O₂ to reoxidize the Fe(II) to Fe(III) prior to analysis. Total dissolved concentrations of iron and copper can be directly obtained on seawater samples at pH 1.7 with this method, eliminating the need to buffer the sample to a higher pH prior to column loading. This resin has the potential to be used in shipboard or in situ flow injection methods.     

Competition Between O2 and H2O2 in the Oxidation of Fe(II) in Natural Waters

The oxidation rates of nanomolar levels of Fe(II) in seawater (salinity S = 36.2) by mixtures of O₂ and H₂O₂ has been measured as a function of pH (5.8–8.4) and temperature (3–35∘C). A competition exists for the oxidation of Fe(II) in the presence of both O₂ (μ mol⋅L⁻¹ levels) and H₂O₂ (nmol⋅L⁻¹ levels). A kinetic model has been applied to explain the experimental results that considers the interactions of Fe(II) with the major ions in seawater. In the presence of both oxidants, the hydrolyzed Fe(II) species dominate the Fe(II) oxidation process between pH 6 and 8.5. Over pH range 6.2–7.9, the FeOH⁺ species are the most active, whereas above pH 7.9, the Fe(OH)⁰₂ species are the most active at the levels of CO²⁻₃ concentration present in seawater. The predicted Fe(II) oxidation rate at [Fe(II)]₀ = 30nmol⋅L⁻¹ and pH = 8.17 in the oxygen-saturated seawater with [H₂O₂]₀ = 50nmol⋅L⁻¹ (log ₁₀ k = −2.24s⁻¹) is in excellent agreement with the experimental value of log ₁₀ k = −2.29s⁻¹ ([H₂O₂]₀ = 55nmol⋅L⁻¹, pH = 8).     

Electrochemical surface plasmon resonance studies on the deposition of the charge-transfer complex from electrooxidation of o-tolidine and effects of dermatan sulfate

The electrochemical surface plasmon resonance (ESPR) technique was used to investigate the electrodeposition of the charge-transfer complex (CTC) generated during electrooxidation of o-tolidine (o-TD) in pH 4.5 Britton–Robinson buffers and the effects of coexisting dermatan sulfate (DS). The peak-type surface plasmon resonance (SPR) responses (versus time) observed in the cyclic voltammetric experiments indicated the precipitation and dissolution of a poorly soluble CTC, an oxidation intermediate, formed during the redox switching of o-TD in a weakly acidic medium. The effects of potential scan rate and solution pH were examined. The height of the peak-type SPR response to the redox switching of the o-TD/CTC “couple” was notably enhanced by the introduction of DS, due to the formation of a mass-enhanced CTC-DS adduct, as also supported by UV–vis spectroelectrochemistry. The SPR signal responded linearly to the DS concentration up to 14 μmol L⁻¹, with a limit of detection (LOD) down to 8 nmol L⁻¹ (S/N = 3). The analytical performance of the ESPR technique was found to be better than that of the quartz crystal microbalance technique with an LOD value of 70 nmol L⁻¹. The CTC-based ESPR assay is recommended as a new, highly sensitive and dynamically surface-regenerated biosensing technology for other species.     

Use of high resolution continuum source atomic absorption spectrometry as a detector for chemically generated noble and transition metal vapors

Vapor generation and atomization conditions in a heated quartz tube to detect Ag, Cd, Co, Cu, Ni and Zn using High Resolution Continuum Source AAS (HRCSAAS), were optimized. Vapors were generated after mixing acidified solutions containing 8-hydroxiquinoline (oxine) with sodium tetrahydroborate. Afterwards, they were swept to the heated quartz cell by an argon flow.Reaction loop size and temperature of the quartz cell were optimized for each element. A temperature of 960 °C was selected as a compromise value to detect most of the metals. Afterwards, a Plackett–Burmann design was proposed to select which parameters were most important. Type of acid and its concentration were the most statistical significant variables. Optimum conditions for sequential detection of Cd, Cu, Ni and Zn were: 1 mg L^− 1 Co as catalyst, 250 mg L^− 1 oxine, 0.6 M nitric acid, 1.75% (w/w) sodium tetrahydroborate (prepared in 0.4 (w/v)% NaOH), a reaction loop of 250 µL, and a 25 L h^− 1 carrier Ar flow. Ag and Co were each detected in their own optimized conditions. Analytical performance of the system was evaluated in connection with a selected pixel number, and spectral correction was used to eliminate NO absorption bands interference in Zn detection. Detection limits were in the range of 1.5–18 μg L^− 1 for Ag, Cu, Cd and Zn, whereas sensitivity was worst for Co (169 μg L^− 1) and Ni (586 μg L^− 1). Atomization in a quartz cell of Co and Ni volatile species, generated by an addition of sodium tetrahydroborate to an acidified solution of the analytes, was reported for the first time in this paper. Precision expressed as RSD(%) had values lower than 10% except for Ni.     

Determination of Trace Amount of Silver by Atomic-Absorption-Spectrometry-Coupled Flow Injection On-Line Coprecipitation Preconcentration Using DDTC–Copper as Coprecipitate Carrier

A flow injection on-line coprecipitation preconcentration system with diethyldithiocarbamate (DDTC) chelate of copper used as the coprecipitate carrier was coupled with flame atomic absorption spectrometry (FAAS) for the determination of trace silver. Silver was on-line coprecipitated with DDTC-Cu(II) in 0.5 moL · L⁻¹HCl, and the precipitate was collected in a knotted reactor. The precipitate was then dissolved by isobutyl methyl ketone and transported directly into the nebulizer–burner system of a flame atomic absorption spectrometer. A detection limit (3ς) of 0.6 μg · L⁻¹was achieved for a loading period of 30 s, a relative standard derivation of 2.0% was obtained for 11 determinations of 20 μg · L⁻¹Ag(I). Interference-free levels were 10 mg · L⁻¹for Cd²⁺, 50 mg · L⁻¹for Cu²⁺, 50 mg · L⁻¹for Mn²⁺, 25 mg · L⁻¹for Ni²⁺, 100 mg · L⁻¹for Pb²⁺, 50 mg · L⁻¹for Zn²⁺, 500 mg · L⁻¹for Fe³⁺, and 2000 mg · L⁻¹for Fe²⁺reduced from Fe³⁺by ascorbic acid. The developed method has been successfully applied to the determination of trace amount of silver in geological samples.     

Equilibrium, kinetics and thermodynamic aspects of Promethazine hydrochloride sorption by iron rich smectite

Equilibrium, kinetics and thermodynamic aspects of sorption of Promethazine hydrochloride (PHCl) onto iron rich smectite (IRS) from aqueous solution were investigated. The effect of pH on sorption of PHCl onto IRS was also found out. Experimental data were evaluated by using Langmuir, Freundlich and Dubinin–Raduschkevich (DR) isotherm equations. Freundlich and DR equations provided better compatibility than Langmuir equation. Besides, it was determined that the maximum sorption of PHCl takes place at about pH 5. From kinetic studies, it was obtained that sorption kinetics follow pseudo-second-order kinetic model for PHCl sorption onto IRS. When thermodynamic studies are concerned, the values of activation energy (E_a), ΔG°, ΔH° and ΔS° were obtained. ΔG° values are in the range of −8.84 and −9.45 kJ mol⁻¹ indicating spontaneous nature of physisorption. The negative value of the ΔH° (−3.20 kJ mol⁻¹) indicates exothermic nature of adsorption. FTIR analysis and SEM observations of IRS and PHCl adsorbed IRS were also carried out. Sorption experiments indicate that IRS may be used effectively for the adsorption of PHCl.     

Absorption-based highly sensitive and reproducible biochemical oxygen demand measurement method for seawater using salt-tolerant yeast Saccharomyces cerevisiae ARIF KD-003

Salt-tolerant yeast Saccharomyces cerevisiae ARIF KD-003 was applied to highly sensitive and reproducible absorbance-based biochemical oxygen demand (BOD_AB-ScII) measurement for seawater. In the previous work, we have studied the BOD_AB-ScI method using normal Baker's yeast S. cerevisiae, and the excellent feature of the Baker's yeast as uniformly sustainable in solution could successfully be utilized. However, the BOD_AB-ScI responses were disappeared by the existence of chloride ion as well as seawater. In the present method, uniformity in solution was also observed with S. cerevisiae ARIF KD-003, and salt-tolerance of the yeast was observed even in saturate concentration of sodium chloride. Next, characterizations of the influences of pH and incubation temperature were investigated. After optimum conditions were obtained, two calibration curves were made between 0.33 and 22 mg O₂ L⁻¹ BOD using standard solution of glucose glutamic acid (GGA) or mixture of GGA and artificial seawater. Then, excellent reproducibility as the averages of relative standard deviation (R.S.D._av) in two calibration curves (nine points each) was successfully obtained at 1.10% at pure water or 1.03% at artificial seawater standard, respectively. In addition, the 3σ lower detection limit was calculated to be 0.07 mg O₂ L⁻¹ BOD, and 0.11 mg O₂ L⁻¹ BOD was experimentally detected by increase of the sample volume at 1.5-folds. The storage stability of the S. cerevisiae ARIF KD-003 was obtained at least 4 weeks.     

The standard partial molar entropy of the aqueous tetra-n-butylammonium cation

The standard partial molar entropy of the aqueous tetrabutylammonium cation, not known previously, has now been obtained, based on the molar entropy of two of its crystalline salts, the iodide and the tetraphenylborate, recently determined experimentally for this purpose. The calculation required also published molar enthalpies of solution and solubilities of these two salts as well as of the perchlorate. The choice of the anions depended mainly on the limited solubilities of the examined salts in water, facilitating the estimation of the relevant activity coefficients. The result is S^∞(Bu₄N⁺, aq) = (380 ± 20) J · K⁻¹ · mol⁻¹ at T = 298.15 K, on the mol · dm⁻³ scale and based on S^∞(H⁺, aq) = (−22.2 ± 1.2) J · K⁻¹ · mol⁻¹ (yielding the ‘absolute’ value). The molar entropy of this cation in the ideal gas standard state, S(Bu₄N⁺, g) = (798 ± 8) J · K⁻¹ · mol⁻¹ then yielded the molar entropy of hydration Δ_hydS^∞ (Bu₄N⁺) = (−418 ± 23) J · K⁻¹ · mol⁻¹.     

Synthesis, spectroscopic and theoretical studies of two novel tripodal imine-phenol ligands and their complexation with Fe(III)

Two novel tripodal imine-phenol ligands, cis,cis-1,3,5-tris{(2-hydroxybenzilidene)aminomethyl}cyclohexane (TMACHSAL, L¹) and of cis,cis-1,3,5-tris{[(2-hydroxyphenyl)ethylidene]aminomethyl}cyclohexane (Me₃-TMACHSAL, L²) have been synthesized and characterized by elemental analyses and various spectral (UV–vis, IR and ¹H and ¹³C NMR) data. The complexation reactions of the ligands with H⁺ and Fe(III) were investigated by potentiometric and spectrophotometric methods at an ionic strength of 0.1 M KCl and 25 ± 1 °C in aqueous medium. Three protonation constants each for ligands L¹ and L² were determined and were used as input data to evaluate the formation constants of the metal complexes. Formations of metal complexes of the types FeLH₃, FeLH₂, FeLH, FeL and FeLH₋₁ were depicted in solution. Experimental evidences suggested for a formation of tris(iminophenolate) type metal complex by the ligands. The ligand L¹ showed higher affinity towards iron(III) than L². The pFe value related to L¹ (pFe = 20.14) is approximately four units higher than L² (pFe = 16.41) at pH = 7.4. The structures of the metal complexes were proposed through the molecular mechanics calculation using MM3 force field followed by semi-empirical PM3 method.     

A multi-syringe flow injection system for the spectrophotometric determination of trace levels of iron in waters using a liquid waveguide capillary cell and different chelating resins and reaction chemistries

A method integrating a long waveguide capillary cell with a preconcentration resin in a multi-syringe flow injection analysis (MSFIA) system for iron determination in waters was developed. The determination of iron is based on a colorimetric reaction and two reagents were tested, ferrozine and ammonium thiocyanate. A liquid waveguide capillary cell (1.0 m pathlength, 550 µm i.d. and 250 µL internal volume) with a preconcentration resin were used to improve the sensitivity of the determination. Two different preconcentration resins were also tested, Chelex 100 and NTA Superflow. The developed method employing the NTA Superflow with ferrozine colorimetric reagent provided a detection limit of 0.05 µg L^− 1 with a linear response up to 8 µg L^− 1 and a sample throughput rate of 12 per hour. The developed system presents low reagents/sample consumptions. The accuracy was assessed using a certified reference water sample.     

Dinitrogen and carbon monoxide hydrogen bonding in protonic zeolites: Studies from variable-temperature infrared spectroscopy

Adsorption (at a low temperature) of nitrogen on the protonic zeolite H-Y results in hydrogen bonding of the adsorbed N₂ molecules with the zeolite Si(OH)Al Brønsted-acid groups. This hydrogen-bonding interaction leads to activation, in the infrared, of the fundamental N–N stretching mode, which appears at 2334 cm⁻¹. From infrared spectra taken over a temperature range, the standard enthalpy of formation of the OH···N₂ complex was found to be ΔH⁰ = −15.7(±1) kJ mol⁻¹. Similarly, variable-temperature infrared spectroscopy was used to determine the standard enthalpy change involved in formation of H-bonded CO complexes for CO adsorbed on the zeolites H-ZSM-5 and H-FER; the corresponding values of ΔH⁰ were found to be −29.4(±1) and −28.4(±1) kJ mol⁻¹, respectively. The whole set of results was analysed in the context of other relevant data available in the literature.     

Comparative studies on hydrolysis of bis(p-nitrophenyl) phosphate catalyzed by short- and long-alkyl-multiamine metallomicelles

Four short- and long-alkyl-multiamine ligands L¹–L⁴ have been synthesized and characterized. The catalytic efficiency of complex CuL¹ and functional metallomicelles CuL²–CuL⁴ were comparatively investigated for the hydrolysis of bis(p-nitrophenyl) phosphate (BNPP) in buffered solution at 30 °C. The ternary kinetic model for metallomicellar catalysis was suggested to analyze the experimental data. The kinetic and thermodynamic parameters k^′_N, K_T and pK_a were obtained. The results indicated that the complexes with 1:1 ratio of ligands L²–L⁴ to copper(II) ion were the kinetic active catalysts, and the deprotonized Cu(II) complex formed by activated water molecule was the real active species for BNPP catalytic hydrolysis. The real rate constant of the reaction catalyzed by CuL¹–CuL⁴ was 4.00 × 10⁻⁶, 7.44 × 10⁻⁵, 1.42 × 10⁻⁴ and 4.10 × 10⁻⁴ s⁻¹, respectively. The effects of ligand and microenvironment on the hydrolytic reaction of BNPP have been discussed in detail.     

Precise measurement of Fe isotopes in marine samples by multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS)

A novel analytical technique for isotopic analysis of dissolved and particulate iron (Fe) from various marine environments is presented in this paper. It combines coprecipitation of dissolved Fe (DFe) samples with Mg(OH)₂, and acid digestion of particulate Fe (PFe) samples with double pass chromatographic separation. Isotopic data were obtained using a Nu Plasma MC-ICP-MS in dry plasma mode, applying a combination of standard-sample bracketing and external normalization by Cu doping. Argon interferences were determined prior to each analysis and automatically subtracted during analysis. Sample size can be varied between 200 and 600 ng of Fe per measurement and total procedural blanks are better than 10 ng of Fe. Typical external precision of replicate analyses (1S.D.) is ±0.07‰ on δ⁵⁶Fe and ±0.09‰ on δ⁵⁷Fe while typical internal precision of a measurement (1S.E.) is ±0.03‰ on δ⁵⁶Fe and ±0.04‰ on δ⁵⁷Fe. Accuracy and precision were assured by the analysis of reference material IRMM-014, an in-house pure Fe standard, an in-house rock standard, as well as by inter-laboratory comparison using a hematite standard from ETH (Zürich). The lowest amount of Fe (200 ng) at which a reliable isotopic measurement could still be performed corresponds to a DFe or PFe concentration of ∼2 nmol L⁻¹ for a 2 L sample size. To show the versatility of the method, results are presented from contrasting environments characterized by a wide range of Fe concentrations as well as varying salt content: the Scheldt estuary, the North Sea, and Antarctic pack ice. The range of DFe and PFe concentrations encountered in this investigation falls between 2 and 2000 nmol L⁻¹ Fe. The distinct isotopic compositions detected in these environments cover the whole range reported in previous studies of natural Fe isotopic fractionation in the marine environment, i.e. δ⁵⁶Fe varies between −3.5‰ and +1.5‰. The largest fractionations were observed in environments characterized by redox changes and/or strong Fe cycling. This demonstrates the potential use of Fe isotopes as a tool to trace marine biogeochemical processes involving Fe.     

Chitosan–magnetite nanocomposites (CMNs) as magnetic carrier particles for removal of Fe(III) from aqueous solutions

This research focuses on removal of Fe(III) from aqueous solution using chitosan–magnetite nanocomposites as potential sorbent. The presence of nanosized magnetic particles within the nanocomposites was confirmed by TEM and SAED analysis. The particles with diameter 508 μm and 84 μm, follow Frendlich sorption isotherm at 30 °C, and the Frendlich constants (K_F, 1/n) have been found to be 5.974 mg g⁻¹, 2.66 and 35.98 mg g⁻¹, 1.385, respectively. Out of various kinetic models, the experimental data for dynamic uptake of Fe(III) is best fitted on ‘pseudo-second order’ kinetic model. The linear nature of plots between log (% sorption) and log (time) is indicative of intra-particle diffusion. For the particles with diameters 508 μm and 84 μm, the value of k_id was found to be 1.78 mg l⁻¹ min^−0.5 and 2.13 mg l⁻¹ min^−0.5. The sorption mean free energy from the Dubinin–Radushkevic isotherm was found to be 7.04 kJ mol⁻¹ indicating chemical nature of sorption. The increase in chitosan content in sorbent particles is found to enhance the Fe(III) uptake. The various thermodynamic parameters have also been evaluated. Finally, the presence of Cu²⁺ ions in the sorbate is found to decrease the uptake of Fe(III).     

Existence of clathrate-like structures in supercooled water: X-ray diffraction evidence

X-ray diffraction study of supercooled water has been performed using an imaging-plate X-ray detector down to −15 °C. The peak at 10.8 Å, which grows with decreasing temperature, in the radial distribution function {D(r) − 4πr²ρ₀} indicates the existence of clathrate-like structures in supercooled water. It is suggested that anomalous properties of water, which become more pronounced at low temperatures, are closely linked to the development of clathrate-like structures in water at low temperatures.     

A novel separation/preconcentration system based on solidification of floating organic drop microextraction for determination of lead by graphite furnace atomic absorption spectrometry

Solidified floating organic drop microextraction (SFODME) was successfully used as a sample preparation method for graphite furnace atomic absorption spectrometry (GFAAS). 20 μL of 1-undecanol containing dithizone as the chelating agent (2 × 10⁻⁴ mol L⁻¹) was transferred to the water samples containing lead ions, and the solution was stirred for the prescribed time. The sample vial was cooled in an ice bath for 5 min. The solidified extract was transferred into a conical vial where it melted immediately, and then 10 μL of it was analyzed by GFAAS.Factors that influence the extraction and complex formation, such as pH, concentration of dithizone, extraction time, sample volume, and ionic strength were optimized. Under the optimized conditions, a good relative standard deviation of ±5.4% at 10 ng L⁻¹ and detection limit of 0.9 ng L⁻¹ were obtained. The procedure was applied to tap water, well water, river water and sea water, and accuracy was assessed through the analysis of certified reference water or recovery experiments.     

Kinetic and thermodynamic analysis of 10-hydroxy-camptothecin hydrolysis at physiological pH

To derive accurately the thermodynamic parameters governing the hydrolysis of the lactone ring at physiological pH, a derivative spectrophotometric technique was used for the simultaneous estimation of lactone and carboxylate forms of the 10-hydroxy-camptothecin (10-HC). Validation of the analytical method was done with respect to reproducibility, percent recovery, and level of detection. Hydrolysis of the lactone ring of 10-HC followed a 1st order decay with a rate constant equal to (0.0281 ± 0.001) min⁻¹ in PBS at pH 7.4 and at a temperature of 310 K. The activation energy for the hydrolysis reaction as calculated from the Arrhenius equation was (79.41 ± 0.92) kJ · mol⁻¹, whereas the enthalpy and entropy of hydrolysis of 10-hydroxy-camptothecin were on average 12.45 kJ · mol⁻¹ and 52.37 J · K⁻¹ · mol⁻¹, respectively. The positive enthalpy and entropy values of the 10-HC-lactone hydrolysis indicate that the reaction is endothermic and entropically driven.     

Diffusion of Sr and Zr in BaTiO3 single crystals

The diffusion of strontium and zirconium in single crystal BaTiO₃ was investigated in air at temperatures between 1000 °C and 1250 °C. Thin films of SrTiO₃, deposited by spin coating a precursor solution and thin films of zirconium, deposited onto the sample surfaces by sputtering, were used as diffusion sources. The diffusion profiles were measured by SIMS depth profiling on a time-of-flight secondary ion mass spectrometer (ToF-SIMS). The diffusion coefficients of strontium and zirconium were given by D_Sr = 3.6 × 10^2.0±4.4 exp[−(543 ± 117) kJ mol⁻¹/(RT)] cm² s⁻¹ and D_Zr = 1.1 × 10^1.0±2.1 exp[−(489 ± 56) kJ mol⁻¹/(RT)] cm² s⁻¹. The results are discussed in terms of different diffusion mechanisms in the perovskite structure of BaTiO₃.     

Selective trace analysis of diclofenac in surface and wastewater samples using solid-phase extraction with a new molecularly imprinted polymer

A new molecularly imprinted polymer (MIP) for trace analysis of diclofenac in environmental water samples was prepared by a non-covalent protocol in which diclofenac was used as a template molecule. Diclofenac is a member of the class of drugs termed non-steroidal anti-inflammatory drugs (NSAIDs) which belong to the most frequently detected pharmaceuticals in the water-cycle in Europe. The MIP was synthesized using 2-vinylpyridine (2-VP) and ethylene glycol dimethacrylate (EGDMA) as a functional monomer and cross-linker, respectively, and bulk thermal polymerization method. ¹H NMR spectroscopy was used to study the interaction between diclofenac and 2-VP mixed in toluene-d₈ in pre-polymerization complex. Two non-covalent bonds were formed i.e. ionic interaction and hydrogen bonding. The binding characteristics of the MIP and diclofenac were evaluated using equilibrium binding experiments. Scatchard plot analysis revealed that two classes of binding sites were formed with dissociation constants of 55.6 μmol L⁻¹ and 1.43 mmol L⁻¹, respectively. Various parameters affecting the extraction efficiency of the polymers have been evaluated to achieve the selective preconcentration of diclofenac from aqueous samples and to reduce non-specific interactions. This resulted in an MISPE-LC/DAD method allowing the direct extraction of the analyte from sample matrix with a selective wash using dichloromethane/acetonitrile (94:6, v/v) followed by elution with dichloromethane/methanol (85:15, v/v). The recovery of a 100 ng diclofenac standard spiked into 200 mL of blank surface water was 96%, with good precision (RSD = 3.3%, n = 3). The MISPE was demonstrated to be applicable to the analysis of diclofenac in raw influent and final effluent wastewater samples from sewage treatment plant and revealed diclofenac concentrations of 1.31 ± 0.055 μg L⁻¹ (n = 3) and 1.60 ± 0.049 μg L⁻¹ (n = 3), respectively. Yielded results were in good agreement with the corresponding LC/TIS/MS/MS data obtained by an independent laboratory which were 1.40 and 1.50 μg L⁻¹ for influent and effluent samples.