Solid-phase Extraction Preconcentration Research Articles

Ultrasound-assisted dispersive magnetic solid phase extraction for preconcentration and determination of trace amount of Hg (II) ions from food samples and aqueous solution by magnetic graphene oxide (Fe3O4@GO/2-PTSC): Central composite design optimization

In this work, the synthesis of the magnetic graphene oxide modified by 2-pyridinecarboxaldehyde thiosemicarbazone groups (Fe3O4@GO/2-PTSC) was utilized for preconcentration and determination of mercuric ions in a trace amount by inductively coupled plasma-optical emission spectrometry (ICP-OES). Characterization of the adsorbent was performed using various techniques, such as FT-IR, VSM, SEM and XRD analysis. Central composite design (CCD) under response surface methodology (RSM) was used for obtaining the most important parameters and probable interactions in variables. The variables such as adsorbent dosage, pH, desorption time, and eluent volume was optimized. These values were 8mg, 5.4min, 0.5mL (HCl, 0.1M), respectively. Sonication had an important role in shortening the adsorption time of Hg (II) ions by enhancing the dispersion of adsorbent in solution. Under the optimal conditions, the proposed method presented high enrichment factor of 193, an extraction percentage of 96.5, a detection limit of 0.0079µgL−1 and a relative standard deviation (RSD %) of 1.63%. Finally, the application of the synthesized material was evaluated for preconcentration and determination of mercuric ions from foods and environmental waters samples.

Detection of reactive aldehyde biomarkers in biological samples using solid-phase extraction pre-concentration and liquid chromatography with fluorescence detection

Fluorescence derivatization allows for detection of lipid peroxidation biomarkers of epilepsy-induced oxidative stress.

Photocatalytic ozonation of urban wastewater and surface water using immobilized TiO2 with LEDs: Micropollutants, antibiotic resistance genes and estrogenic activity

Photocatalytic ozonation was employed for the first time in continuous mode with TiO2-coated glass Raschig rings and light emitting diodes (LEDs) to treat urban wastewater as well as surface water collected from the supply area of a drinking water treatment plant (DWTP). Different levels of contamination and types of contaminants were considered in this work, including chemical priority substances (PSs) and contaminants of emerging concern (CECs), as well as potential human opportunistic antibiotic resistant bacteria and their genes (ARB&ARG). Photocatalytic ozonation was more effective than single ozonation (or even than TiO2 catalytic ozonation) in the degradation of typical reaction by-products (such as oxalic acid), and more effective than photocatalysis to remove the parent micropollutants determined in urban wastewater. In fact, only fluoxetine, clarithromycin, erythromycin and 17-alpha-ethinylestradiol (EE2) were detected after photocatalytic ozonation, by using solid-phase extraction (SPE) pre-concentration and LC-MS/MS analysis. In surface water, this treatment allowed the removal of all determined micropollutants to levels below the limit of detection (0.01–0.20 ng L−1). The efficiency of this process was then assessed based on the capacity to remove different groups of cultivable microorganisms and housekeeping (16S rRNA) and antibiotic resistance or related genes (intI1, blaTEM, qnrS, sul1). Photocatalytic ozonation was observed to efficiently remove microorganisms and ARGs. Although after storage total heterotrophic and ARB (to ciprofloxacin, gentamicin, meropenem), fungi, and the genes 16S rRNA and intI1, increased to values close to the pre-treatment levels, the ARGs (blaTEM, qnrS and sul1) were reduced to levels below/close to the quantification limit even after 3-days storage of treated surface water or wastewater. Yeast estrogen screen (YES), thiazolyl blue tetrazolium reduction (MTT) and lactate dehydrogenase (LDH) assays were also performed before and after photocatalytic ozonation to evaluate the potential estrogenic activity, the cellular metabolic activity and the cell viability. Compounds with estrogenic effects and significant differences concerning cell viability were not observed in any case. A slight cytotoxicity was only detected for Caco-2 and hCMEC/D3 cell lines after treatment of the urban wastewater, but not for L929 fibroblasts.

On-line flow injection molecularly imprinted solid phase extraction for the preconcentration and determination of 1-hydroxypyrene in urine samples

New analytical strategies tend to automation of sample pre-treatment and flow analysis techniques provided a number of enhanced analytical methods allowing high throughput. Flow techniques are usually faster, more robust and more flexible than their batch equivalents. In addition, flow methods use less sample and reagent amounts and reduce analytical costs and waste.A flow injection solid-phase extraction pre-concentration system using a molecularly imprinted polymer (MIP) packed micro-column was developed for the determination of 1-hydroxypyrene in human urine with fluorescence detection. The pre-concentration of 1-hydroxypyrene on the MIP was carried out based on the specific retention of analyte by on-line introducing the sample into the micro-column system. Methanol and dichloromethane mixture was used to elute the retained analyte for fluorometric analysis. Important influencing factors were studied in detail, in batch and in flow (MISPE procedure optimisation, sample and eluent volumes, flow rate, dimensions of MIP micro-column and amounts of packing material, etc).To the best of our knowledge, this is the first on-line flow injection molecularly imprinted solid phase extraction for the pre-concentration and determination of hydroxylate PAH metabolite in urine samples.The optimised method was successfully applied to the determination of 1-Hydroxypyrene in spiked urine samples, with recoveries in the range of 74–85% and RSD<4.6%. Under optimum experimental conditions, the linearity concentration range used was 10–400μgL−1, R2>0.996. We obtained limit of detection and quantification of 3.1μgL−1 and 10.5μgL−1, respectively.

Solid Phase Extractive Pre-Concentration of Uranium(VI) from Liquid Waste onto Peach Stone Steam Pyrolysis Activated Carbon

Solid Phase Extractive Pre-Concentration of Uranium(VI) from Liquid Waste onto Peach Stone Steam Pyrolysis Activated Carbon

New approach for the simultaneous determination fungicide residues in food samples by using carbon nanofiber packed microcolumn coupled with HPLC

Solid-phase extraction preconcentration system using carbon nanofibers (CNFs) packed microcolumn was developed for the simultaneous determination of the fungicides carbendazim (MBC) and thiabendazole (TBZ) by high performance liquid chromatography (HPLC). CNFs exhibited a good affinity to target analytes. Important influence factors were studied in detail, such as amounts of packing material, sample solution acidity, sample flow rate and volume, eluent flow rate and volume. Under the optimal conditions, excellent linearity was obtained in a range of 2.0–500.0 ng mL−1 with a correlation coefficient of r2 ≥ 0.9964. The limits of quantification and detection were in the range of 1.50–1.80 ng mL−1 and 0.45–0.54 ng mL−1, respectively. The present method was applied to the analysis of fruit, vegetable and juice samples, and the recoveries of analytes were in the range of 96.1–103.5% with the relative standard deviations ranging from 1.27% to 3.90% (n = 3). Intra-day and inter-day repeatability values expressed as relative standard deviation were 1.08–2.74% and 2.82–3.94%, respectively. The results showed that the present method was a simply, convenient and feasible method for the determination of MBC and TBZ in real samples.

Determination of Cu(2+), Zn(2+) and Pb(2+) in biological and food samples by FAAS after preconcentration with hydroxyapatite nanorods originated from eggshell.

Hydroxyapatite nanorods (HAPNRs) were prepared from recycled eggshell by using precipitation method. The structure of the HAPNRs was physicochemically and morphologically characterized by X-ray diffraction, transmission electron microscopy and Fourier transform infrared spectroscopy. The resulting HAPNRs were used for solid phase extractive preconcentration of Cu(2+), Zn(2+) and Pb(2+) prior to its determination by flame atomic absorption spectrometry. Experimental variables that influence the quantitative extraction of metal ions were optimized by both batch and column methods. The analytes were quantitatively sorbed on the matrix between pHs6 and 9. The maximum sorption capacity of the HAPNRs has been found to be 2.43, 2.37 and 2.53 mmol g(-1) for Cu(2+), Zn(2+) and Pb(2+), respectively, with the preconcentration factor of 250. The 3σ detection limit and 10σ quantification limit for Cu(2+), Zn(2+) and Pb(2+) were found to be 0.72, 0.55 and 5.12 μg L(-1) and 2.40, 1.83 and 17.06 μg L(-1), respectively. The calibration curves were linear up to 250 μg L(-1) for Cu(2+), 300 μg L(-1) for Zn(2+) and 400 μg L(-1) for Pb(2+). Accuracy of the proposed method was verified using certified reference materials (NCS ZC85006 Tomato, Seronorm Trace Elements Whole Blood L-1, Seronorm Trace Elements Whole Blood L-3 and Seronorm Trace Elements Urine). The present method was successfully applied to the analysis of these metal ions in sea water, biological and food samples.

Mercury speciation in seawater by liquid chromatography-inductively coupled plasma-mass spectrometry following solid phase extraction pre-concentration by using an ionic imprinted polymer based on methyl-mercury–phenobarbital interaction

Trace levels of inorganic mercury, methyl-mercury and ethyl-mercury have been assessed in seawater by high performance liquid chromatography (HPLC) hyphenated with inductively coupled plasma-mass spectrometry (ICP-MS) after solid phase extraction (SPE) pre-concentration with a novel synthesized ionic imprinted polymer. The adsorbent material was prepared by trapping a non-vinylated chelating ligand (phenobarbital) via imprinting of a ternary mixed ligand complex of the non-vinylated chelating agent, the template (methyl-mercury), and the vinyl ligand (metacrylic acid, MAA). Ethylene dimetacrylate (EDMA) and 2,2′-azobisisobutyronitrile (AIBN) were used as cross-linker and initiator reagents, respectively; and the precipitation polymerization technique was used in a porogen of acetonitrile/water (4:1). The best retention properties for methyl-mercury, inorganic mercury and ethyl-mercury species from seawater were obtained when loading 200mL of sample adjusted to pH 8.0 and at a flow rate of 2.0mLmin−1 on a column-packed with 200mg of the material. Quantitative mercury species recoveries were obtained using 4mL of an eluting solution consisting of 0.8% (v/v) 2-mercaptoethanol and 20% (v/v) methanol (pH adjusted to 4.5) pumped at a flow rate of 2.0mLmin−1. Mercury species separation was achieved on a Kinetex C18 column working under isocratic conditions (0.4% (v/v) 2-mercaptoethanol, 10% (v/v) methanol, pH 2.5, flow rate 0.7mLmin−1). ICP-MS detection was performed by monitoring the mercury mass to charge ratio of 202. The limits of quantification of the method were 11, 6.7, and 12ngL−1, for inorganic mercury, methyl-mercury and ethyl-mercury, respectively (pre-concentration factor of 50); whereas, analytical recoveries ranged from 96 to 106%. The developed method was successfully applied to several seawater samples from unpolluted areas.

Ultrasonic-Assisted Solid-Phase Extraction Pre-concentration and Determination of Nicotinamide and Nicotinic Acid by High-Performance Liquid Chromatography Using Anthracite

This study introduces a novel method of ultrasonic-assisted solid-phase extraction, pre-concentration, and reversed-phase high-performance liquid chromatography to determine nicotinamide (NAM) and nicotinic acid (NAC) from an aqueous solution using anthracite particles (ANTCs). Results demonstrated that ANTCs were quite efficient for use in extraction and pre-concentration of traces of NAM and NAC at 25 °C. Tests investigated the effects of the parameters: pH, buffer and its volume, electrolyte concentration, composition and volume of the desorbing solvent, accepted tolerable volume, amount of adsorbent, ultrasonic radiation time, and evidence of some co-existing ions on pre-concentration and determinations of NAM and NAC. The method showed good linearity for determination of these compounds in the range of 0.0025–10 μg mL−1 with regression coefficients of 0.999. Evaluations for limits of detection were 6 × 10−4 and 7 × 10−4 μg mL−1 for NAM and NAC, respectively. Intra- and inter-day relative standard deviations for 0.2 and 5 μg mL−1 were below 3.5 % and 4.6 %, respectively. Samples of rice, coffee, spice, spaghetti, tea, and B-complex syrup with potential niacin content were used as real samples, and NAM and NAC in the samples and spiked samples were pre-concentrated and determined successfully.

Solid-Phase Extractive Preconcentration of Trace Copper as its Calmagite Anionic Chelate using a Polyaniline Column for Flame Atomic Absorption Spectrometric Determination

A new solid phase extraction method based on the application of polyaniline as the sorbent and calmagite as the anionic chelating agent is reported for selective preconcentration of trace copper, prior to its determination by microsample injection system-flame atomic absorption spectrometry. The parameters that influence the extraction and chelate formation were optimized. The copper was retained on a polyaniline minicolumn at pH 4.0 and eluted with 2.0 mL of 3.0 mol L−1 nitric acid. Under the optimum conditions, the limit of detection, the relative standard deviation, and the preconcentration factor were 1.98 µg L−1, less than 5.4%, and 50 to 200, respectively. The method was validated through the analysis of certified reference water samples and standard addition measurements. Quantitative recoveries between 93.4% and 103.5% were obtained. The method was successfully applied to the determination of copper in water.

Suspension Dispersive Solid Phase Extraction for Preconcentration and Determination of Cobalt, Copper, and Nickel in Environmental Water by Flame Atomic Absorption Spectrometry

A novel preconcentration technique termed suspension dispersive solid phase extraction (SDSPE) was developed for selective separation and preconcentration of cobalt, nickel, and copper in environmental water. The method is based on the reaction of zinc sulfate and sodium hydroxide to form zinc hydroxide. The suspension results from the dispersion of the fine particles of the sorbent in the aqueous sample. The complexes of metal ions in the bulk aqueous sample with 1-(2-pyridylazo)-2-naphthol (PAN) were loaded on sorbents. After extraction, phase separation was performed by centrifugation and the enriched analyte in the sedimented phase was eluted by methanol and determined by flame atomic absorption spectrometry. Key parameters such as the type and mass of sorbent, type and volume of eluent, concentration of the chelating agent, equilibration time, and sample volume were optimized and an enrichment factor of 20 was obtained with a sample volume of 40 mL. The limits of detection for Co, Ni, and Cu were 2.4, 1.7, and 1.5 µg L−1, respectively. The relative standard deviations were 4.3%, 2.7%, and 1.6% at 10 µg L−1 for Co, Ni, and Cu, respectively. The method was successfully employed for the determination of these metals in environmental waters.

Application of molecular imprinted polymer nanoparticles as a selective solid phase extraction for preconcentration and trace determination of 2,4-dichlorophenoxyacetic acid in the human urine and different water samples.

A molecular-imprinted polymer nanoparticles (MIP-NP) for the selective preconcentration of 2,4-dichlorophenoxyacetic acid (2,4-D) is described. It was obtained by precipitation polymerization from methacrylic acid (the functional monomer), ethylene glycol dimethacrylate (the cross-linker), 2,2′-azobisisobutyronitrile (the initiator) and 2,4-D (the template molecule) in acetonitrile solution. The MIP-NPs were characterized by thermogravimetric analysis, and by scanning electron microscopy. Imprinted 2,4-D molecules were removed from the polymeric structure using acetic acid in methanol (15:85 v/v %) as the eluting solvent. The sorption and desorption process occur within 10 min and 15 min, respectively. The maximum sorbent capacity of the molecular imprinted polymer is 89.2 mg g−1. The relative standard deviation and limit of detection for water samples by introduced selective solid phase extraction were 4.2% and 1.25 μg L−1, and these data for urine samples were 4.7% and 1.80 μg L−1, respectively. The method was applied to the determination of 2,4-D in the urine and different water samples.

Computer-assisted design and synthesis of molecularly imprinted polymers for the simultaneous determination of six carbamate pesticides from environmental water.

The computer-assisted design and synthesis of molecularly imprinted polymers for the simultaneous capture of six carbamate pesticides from environmental water are reported in this work. The quantum mechanical computational approach was employed to design the molecularly imprinted polymers with carbofuran as template. The interaction energies between the template molecule and different functional monomers in various solvents were calculated to assist in the selection of the functional monomer and porogen. The optimised molecularly imprinted polymer was subsequently used as a class-selective sorbent in solid-phase extraction for pre-concentration and determination of carbamates from environmental water. The parameters influencing the extraction efficiency of the molecularly imprinted solid-phase extraction procedure were systematically investigated to facilitate the class-selective extraction. For the proposed method, linearity was observed over the range of 2-500ng/mL with the correlation coefficient ranging from 0.9760 to 1.000. The limits of detection ranged from 0.2 to 1.2ng/mL, and the limit of quantification was 4ng/mL. These results confirm that computer-assisted design is an effective evaluation tool for molecularly imprinted polymers synthesis, and that molecularly imprinted solid-phase extraction can be applied to the simultaneous analysis of carbamates in environmental water.

Multivariate optimization of dual-bed solid phase extraction for preconcentration of Ag, Al, As and Cr in gasoline prior to inductively coupled plasma optical emission spectrometric determination

In this work, a dual-bed resin solid phase extraction (SPE) for preconcentration of Ag, Al, As and Cr prior to their inductively coupled plasma-optical emission spectroscopy (ICP-OES) determination has been developed. Dowex 50W-x8 and Dowex 1-x8 packed in a column were used as metal ion sorbents. The optimization of the dual-bed SPE procedure was carried out using a two level full factorial design with three central points. Under optimized conditions, the limits of detection and quantification (n=21) ranged from 0.16 to 0.22 and 0.52 to 0.76μgL−1, respectively. Enrichment factors of 100, 130, 130 and 150 and relative standard deviations (n=15) of 1.2%, 2.0%, 1.8% and 1.3% were obtained in the determination of Ag, Al, As and Cr, respectively. The validity of the proposed method was checked by applying the standard addition method and the recoveries at the 20μgL−1 level using both inorganic and organic metal standards ranged from 95% to 99%. The proposed method presented an analytical throughput of about 18 samples per hour and was applied for the determination of metal ions in ten gasoline samples. In addition, the accuracy of the method was evaluated using microwave-assisted digestion method and the results were not significantly different (at 95% confidence level).

Solid phase extractive preconcentration of Uranium from Jordanian phosphoric acid using 2-hydroxy-4-aminotriazine-anchored activated carbon

Jordanian phosphate ore contains 70–150parts per million (ppm) uranium. The uranium in the ore tends to dissolve during the leaching of phosphate ore with sulfuric acid to produce phosphoric acid (PA). Solvent extraction (SX) using various extracting agents is widely used to extract uranium from PA. Meanwhile, much research work has been carried out to develop suitable solid phase extractants in order to reduce cost and enhance efficiency. In this study, a new solid phase extractant has been synthesized by anchoring 2-hydroxy-4-aminotriazine onto activated carbon (ACH). The extraction of uranium from Jordanian PA using ACH and the synergistic mixture of di-ethylhexyl phosphoric acid and trioctyl phosphine oxide (DEPA–TOPO) diluted in kerosene were investigated and the performance of each extractant was evaluated and compared. The results showed that 91% extraction and 559.9ppm loading capacity were achieved after 2 to 3min mixing time using 0.5M DEPA–0.125M TOPO at 20°C, 410mV and 1/1 phase ratio. The activation energy (Ea) of the solvent extraction (−26.03kJmol−1), calculated from Arrhenius plot, indicates that the reaction is barrier-less and exothermic in nature. On the other hand, uranium sorption onto ACH reaches equilibrium after 10min and about 92% extraction can be achieved at 20°C, Co=70mg/l, V=200ml, W=100mg and 410mV; the rate constant for the uranium sorption onto ACH (16.54×10−3gmg−1min−1) was calculated from the pseudo-second order equation. The countercurrent extraction results showed that ACH has high physical, chemical stability and loading capacity about 618mgg−1. Thermodynamic parameters (ΔHads°=20.61kJmol−1, ΔSads°=160.47Jmol−1K−1, ΔGads° (333.3K)=−32.87kJmol−1) suggest that the adsorption is endothermic and spontaneous in nature, which confirm the feasibility of the process.

Determination of traces of copper and zinc in honeys by the solid phase extraction pre-concentration followed by the flame atomic absorption spectrometry detection.

A simple and fast solid phase extraction procedure was developed to pre-concentrate traces of Cu and Zn prior to their determination in honey samples by flame atomic absorption spectrometry. The sample preparation included dissolution of honey samples and the passage (at 20 ml/min) of resulting 10 % m/v solutions (100 ml) through Dowex 50W × 8-400 resin beds in order to quantitatively retain Cu and Zn and separate them from the glucose and fructose matrix. Enriched Cu and Zn traces were recovered with 5.0 ml of a 3.0 mol/l HCl solution and quantified by flame atomic absorption spectrometry. The procedure proposed was used to analyze sixty nine commercially available and freshly ripened honey samples coming from the Lower Silesia region (Poland). It enabled to measure Cu and Zn within the range of 0.01–1.42 and 0.03–15.38 μg/g, respectively, with precision better than 4 %. Accuracy, assessed on the basis of the recovery test and the comparison of results with those obtained using wet digestion and inductively coupled plasma optical emission spectrometry, was ranged from −4 % to +6 %. Detection limits of Cu and Zn achieved with this method were 5 and 7 ng/g, respectively.

The Simultaneous Determination of Six Flame Retardants in Water Samples Using SPE Pre-concentration and UHPLC-UV Method

Analytical method for the determination of six flame retardants (FRs) from two groups was proposed. These groups included the brominated flame retardants (BFRs) 3,3′,5,5′-tetrabromobisphenol A (TBBPA), 1,2,5,6,9,10-hexabromocyclododecane (HBCD) and tetrabromophthalic anhydride (TBPA) and triester organophosphate flame retardants (OPFRs) tris(2,3-dibromopropyl) phosphate (TBPP), ethylhexyl diphenyl phosphate (EHDP) and triphenyl phosphate (TPhP). Reversed phase ultrahigh-performance liquid chromatography (UHPLC) with a UV detector, different chromatographic columns, different mobile phases and gradient elution programmes were used to obtain the best separations within the shortest possible time. Solid-phase extraction (SPE) was examined as a pre-concentration step from distilled water. The column with the highest recoveries (the Bond Elut ENV column gave recoveries over 70 % for all compounds) was then tested on 1-L blank surface water samples. The proposed analytical procedure was applied for the determination of FRs in surface water samples. The concentrations of FRs found in water samples ranged from 0.03 (TPhP) to 3.10 μg L−1 (HBCD). Method detection limits (MDLs) ranged from 0.008 to 0.518 μg L−1, and method quantification limits (MQLs) ranged from 0.023 to 1.555 μg L−1 for all compounds.

Ligand-Lessin situSurfactant-Based Solid Phase Extraction for Preconcentration of Cobalt, Nickel and Zinc from Water Samples Prior to their FAAS Determination

A new simple and rapid ligand-less in situ surfactant-based solid phase extraction (LL-ISSPE) was developed for preconcentration of cobalt, nickel and zinc in water samples. In this method, a cationic surfactant containing a proper alkyl group (n-dodecyltrimethylammonium bromide) is dissolved in the aqueous sample and then a proper ion-pairing agent (ClO4−) is added. Due to the interaction between surfactant and ion-pairing agent, solid particles are formed and precipitate of the analytes was adsorbed on surface of sorbent. After centrifugation, the sediment is dissolved in 3.0 mL HNO3 in ethanol and then aspirated directly into the flame atomic absorption spectrometer. Variables affecting the extraction efficiencies such as pH, concentrations of surfactant and ion pair, CO32− amount, extraction time, time and rate of centrifuge were optimized. Detection limits for Co(II), Ni(II) and Zn(II) based on 3Sb/m were 1.0, 1.5 and 0.3 ng mL−1, respectively. The proposed method has been successfully applied for the determination of cobalt, nickel and zinc ions in real water samples.

A new method for preconcentration and determination of mercury in fish, shellfish and saliva by cold vapour atomic absorption spectrometry

The development of a method using solid phase extraction for preconcentration and determination of mercury by cold vapour atomic absorption spectrometry is described. Hg (II) ions are sorbed on a minicolumn packed with Amberlite XAD-4 sorbent functionalised with 2-(2′-benzothiazolylazo)-p-cresol (BTAC). Then, a reducing solution was used for desorption and the transport of the analyte for subsequent detection. The assay presented a limit of detection of 0.011μgL−1 (0.011μgg−1, for solid samples), a limit of quantification of 0.038μgL−1 (0.038μgg−1, for solid samples), a precision of 0.50% (1.000μgL−1 Hg solution) and an enrichment factor of 46. The proposed method was applied to the determination of mercury in human saliva (0.055–0.200μgL−1). The following seafood collected in Todos os Santos Bay, Brazil was also analysed: bass (0.169–0.195μgg−1), mullet (0.043–0.361μgg−1), shrimp (0.075–0.374μgg−1) and mussel (0.206–0.397μgg−1).

An FAAS assay utilizing graphene nanosheets-based solid-phase extraction for preconcentration and determination of trace amounts of palladium

A solid-phase extraction procedure is presented for the separation and preconcentration of trace levels of Pd(II) ion by using exfoliated graphene nanosheets (GNs). Experimental parameters such as extraction time, pH, type of eluent, sample volume and temperature were studied in detail. The Pd(II) adsorbed on the GNs was eluted with 1.5 mol L−1 sodium thiosulfite and then determined by flame atomic absorption spectrometry. The effects of potentially interfering ions on the recovery of Pd(II) were also examined. Under optimized conditions, the method provided a preconcentration factor of 100, had a linear range from 5.0 to 100 ng mL−1 of Pd(II), a limit of detection 2.1 ng mL−1, and a relative standard deviation 1.1 % at 20 ng mL−1 of Pd(II). The method was validated by the extraction and determination of Pd(II) in water, tea, lentil and bovine liver samples.