Eluent Volume Research Articles

A new method for the speciation of arsenic species in water, seafood and cigarette samples using an eggshell membrane

This work is based on the application of the eggshell membrane (ESM) of fresh chicken as a sorbent in a solid phase extraction procedure for arsenic speciation with detection by electrothermal atomic absorption spectrometry. The ESM can adsorb several heavy metal ions from a dilute aqueous solution with high affinity and short contact time, depending on pH and ionic characteristics. It thusly becomes a promising candidate as a solid adsorbent in extraction systems. The procedure is based on the solid phase extraction of the complex formed by As(III) with ammonium pyrrolidine dithiocarbamate (APDC). Solutions of As(III) were percolated through the eggshell membrane-filled minicolumn (ESM). Then, the analyte contained in the sorbent was desorbed by a 4.0 mol L−1 HNO3/ethanol solution (2:3). The influence of variables such as eluent, sample volume, pH effect, APDC volume, eluent volume, atomization, pyrolysis temperature, and sample flow was studied. Under optimized conditions, the method presented a limit of detection and enrichment factor of 0.01 μg L−1 and 17, respectively. Arsenic speciation was also tested because As(V) does not react with APDC, but is retained by ESM. Thus, the determination of total arsenic and As(V) allows the determination of both species. The procedure was applied to the determination of arsenic species in water, seafood, and cigarette samples.

Electrospun Nylon-66/5-(4-dimethylaminobenzyliden) rhodanine composite nanofibres for solid phase extraction of palladium ions from wastewater samples

ABSTRACTIn the present work, a simple procedure is presented for the extraction and determination of pre-concentrated trace amounts of palladium ions through solid phase extraction (SPE) and flame atomic absorption spectrophotometry. This process was performed using Nylon-66/5-(4-dimethylaminobenzylidene) rhodanine composite nanofibres. These nanofibres were produced under optimised conditions via two-axial electrospinning technique and characterised by scanning electron microscopy and Fourier-transform infrared spectroscopy. The effect of experimental parameters including solution pH, the type and volume of eluent and contact time was investigated in extraction and desorption process. Under the optimised conditions, good linearity in the range of 0.07–8 μg L−1 and low detection limit of 0.015 μg L−1 were obtained. High enrichment factor of 187.5 and good relative standard deviation of ±2.2% at 5 μg L−1 of palladium had been achieved. The sorbent capacity for palladium adsorption was obtained 27 mg palladium per gram of nanofibres. So, the SPE was successfully applied to pre-concentrate and determine Pd(II) ions with flame atomic absorption spectrophotometer in real samples.

Cesium removal from AP-105 Hanford tank waste using spherical resorcinol formaldehyde resin

ABSTRACTSpherical resorcinol formaldehyde (SRF) resin is planned for use in removing cesium (137Cs) from Hanford tank waste supernates in preparation for waste vitrification at the Waste Treatment and Immobilization Plant. The results of six complete load/elute cycles using 12 L of Hanford tank waste supernatant collected from Tank AP-105 are provided. Testing exposed SRF to the combined sources of chemical degradation, physical stresses, and radiolytic exposure. Decreased flowrates and increased elution volumes improved performance. Increased cycling decreased performance; increased flowrate increased mass transfer zones; Cs leakage into ensuing cycle increased with decreased eluate volume, and analyte mass fractionation were examined.

Determination of Six Macrolide Antibiotics in Chicken Sample by Liquid Chromatography-Tandem Mass Spectrometry Based on Solid Phase Extraction.

In this paper, a simple and effective method for the determination of six macrolide antibiotics (MACs), including tylosin, tilmicosin, azithromycin, clarithromycin, roxithromycin, and kitasamycin, in the chicken sample using liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed based on a self-built porous aromatic framework- (PAF-) based solid phase sorbent. The main parameters influencing the extraction efficiency, such as sorbent amounts, type of the eluent, pH of the sample, and the eluent volume, were evaluated. Under the optimized condition, the limits of detection were from 0.2 to 0.5 μg·kg−1. The recoveries of the method ranged from 82.1% to 101.4% with the relative standard deviations less than 11.1%. All the results demonstrated that the established method is potential for the determination of macrolide antibiotics in food safety analysis and monitoring.

Application of magnetized MOF‐74 to phthalate esters extraction from Chinese liquor

In this study, magnetized MOF-74 (Ni) was prepared using an ultrasound-assisted synthesis method. This novel functional magnetic adsorbent was characterized using various techniques. Using the prepared material as adsorbents, a magnetic solid-phase extraction method coupled with high-performance liquid chromatography was proposed for determining four phthalate esters in Chinese liquor samples. The extraction parameters, including solution pH, adsorbent amount, extraction time, and eluent type and volume, were optimized. Under the optimized conditions, proposed method showed good linearity within the range of 1.53-200 μg/L for diphenyl phthalate, 2.03-200 μg/L for butyl benzyl phthalate, 7.02-200 μg/L for diamyl phthalate, and 6.03-200 μg/L for dicyclohexyl phthalate, with correlation coefficients>0.9944, low limits of detection (0.46-2.10 μg/L, S/N=3), and good extraction repeatability (relative standard deviations of 3.7%, n=6). This method was successfully used to analyze phthalate esters in Chinese liquor samples with recoveries of 74.4-104.8%. Two phthalate esters were detected in two samples, both at concentrations that satisfied the Chinese national standard, indicating this method has practical application prospects. The extraction efficiency of this method was also compared with conventional solid-phase extraction using commercial C18 cartridges. The results demonstrated that the proposed magnetic solid-phase extraction is a simple, time-saving, efficient, and low-cost method.

Solid-Phase Extraction Method by Magnetic Nanoparticles Functionalized with Murexide for Trace U(VI) from Sea Water Prior to Spectrophotometric Determination

In this study, magnetic nanoparticles (Fe3O4/SiO2/APTES) functionalized with murexide were used for the determination of uranium(VI) in sea water by spectrophotometric method in perchloric acid medium using Arsenazo-III as chromogenic reagent. The effects of some analytical parameters, such as pH, contact time, and eluent volume, on the recovery of uranium(VI) were examined in synthetic sea water. The optimum conditions were achieved with a 15 min adsorption time and 2 min elution time with 1 mL of 5 mol L-1 HClO4 at pH of 6.5 and 25 mg of the magnetic sorbent. The linear range, detection limit, and precision (as RSD%) of the method were found to be 0.02-4.0 mg L-1, 0.001 mg L-1 and 3.0%, respectively. The proposed method is simple, rapid, and cost-effective for the determination of U(VI) in sea water, with a total analysis time of approximately 30 min. The adsorption isotherm was well fitted to the Langmuir model, with a correlation coefficient of 0.9997 and Qmax value was found to be 77.51 mg g-1. The magnetic sorbent was successfully used for the rapid determination of trace quantities of U(VI) ions in different sea waters, and satisfactory results were obtained.

Nanostructured polyaniline based pipette tip solid phase extraction coupled with high-performance liquid chromatography for the selective determination of trace levels of three sulfonamides in honey and milk samples with the aid of experimental design methodology

In this study, a miniaturized solid-phase extraction based on 2-(hexyloxy) naphthalene-sulfate doped polyaniline polymer as a new nanostructured sorbent packed into a 200 μL pipette tip (PT-SPE) as a rapid and efficient method was developed for the simultaneous and selective extraction of three sulfonamide (SAs) antibiotics in aqueous solution. The resultant polymer was well characterized by FT-IR, UV–Vis., FESEM, EDX and XRD. In this strategy, the pipette tip containing the sorbent was matched to a syringe and the sample solution was loaded onto the sorbent using a microsyringe pump. The eluate was analyzed with high performance liquid chromatography using UV–Vis. spectrometry detection (HPLC/UV–Vis). In preliminary experiments, sample pH, sorbent dosage, sample volume and eluent volume were identified as critical variables affecting the solid phase micro-extraction of SAs by the developed sorbent. The response surface methodology (RSM) based on a rotatable central composite design (CCD) was employed for modeling the chromatographic peak areas of SAs as responses and optimized the effective extraction variables. This method is cost-effective because only 7.4 mg sorbent amount and 0.6 mL methanol as eluent were required for the extraction of analytes. The multiple response criteria were used to optimize simultaneous responses of the analytes using the desirability function. Under the optimal conditions, a good linear relationship between the peak areas and concentrations of the SAs was found in the range of 50–50,000 ng mL−1 with correlation coefficients above 0.999. The developed method was successfully applied to the analysis of SAs in milk, and honey samples.

Antibiotic elution and compressive strength of gentamicin/vancomycin loaded bone cements are considerably influenced by immersion fluid volume.

The effect of doubling the immersion fluid (eluate) volume on antibiotic concentrations and on mechanical stability from vancomycin and gentamicin loaded bone cements was investigated in vitro. Antibiotic loaded bone cements containing premixed 1.34% gentamicin antibiotic concentration in the cement powder (wt), premixed 1.19% gentamicin wt and 4.76% vancomycin wt and premixed 1.17% wt gentamicin additionally manually blended with 4.68% wt vancomycin were tested. Six specimens per group were immersed in 4 ml and 8 ml for 6 weeks while the eluate was exchanged every 24 h. The antibiotic concentrations were repeatedly measured. Then the specimens were tested for compressive strength. Doubling the eluate volume significantly decreased gentamicin and vancomycin concentrations from 6 h and 24 h on, except for the gentamicin concentration of the additionally manually blended formulation after 3 weeks. The additionally manually blended vancomycin formulation produced significantly higher gentamicin concentrations in 8 ml compared to the other formulations. The reduction ratios of the vancomycin concentrations were significantly smaller than the reduction ratios of the gentamicin concentrations for the manually blended vancomycin formulation. Vancomycin containing formulations showed significantly lower compressive strengths than the vancomycin free formulation after immersion. Doubling the eluate volume lead to significant compressive strength reduction of the vancomycin containing formulations. Eluate volume change influences antibiotic elution dependent on the antibiotic combination and loading technique. The reducing effect is higher on vancomycin than on gentamicin elution. Compressive strength of gentamicin/vancomycin loaded bone cements after immersion is eluate volume dependent.

Dispersive solid phase extraction of lead in water samples using embedded 1,5-diphenylcarbazone grafted graphene oxide in microporous magnetic chitosan coupled with flame atomic absorption spectrometry

In the current study, an embedded 1,5-diphenylcarbazone (DPC) grafted graphene oxide (GO) in porous magnetic chitosan (MC) nanocomposite was synthesized and used for preconcentration of trace amount of Pb(II). For this purpose, a magnetic dispersive solid phase extraction (MDSPE) was utilized prior to determination by flame atomic absorption spectrometry (FAAS). The adsorbent was characterized using Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). The parameters influencing the extraction efficiency such as pH, extraction and desorption time, adsorbent amount and type, concentration and volume of eluent were optimized by design of experiment. Under the optimum conditions, calibration curve was linear within the range of 3.0–300 ng mL−1 with regression coefficient of 0.9957. The enhancement factor was obtained as 13.5 corresponding to the absolute recovery of 81%. The limits of detection (LOD, 3Sb/m) and quantification (LOQ) were found to be 0.13 ng mL−1 and 0.43 ng mL−1, respectively. Intra- and inter-day precisions (n = 5) were estimated using the relative standard deviation (RSD%) at three concentrations of 25, 100 and 250 ng mL−1 and were less than 3.2% and 5.6%, respectively. The maximum adsorption capacity (qm), calculated by the Langmuir equation, was found to be 57.47 mg g−1. The method was validated by analysis of an SRM-1643f standard reference material for trace elements in water. Finally, the method was successfully applied for the determination of trace amount of Pb(II) in various water samples with good relative recoveries ranged from 92.3 to 105%.

Ultrasound-assisted dispersive solid phase extraction based on Fe3O4/reduced graphene oxide nanocomposites for the determination of 4-tert octylphenol and atrazine by gas chromatography–mass spectrometry

A magnetic Fe3O4/reduced graphene oxide composite was synthesized by a one-step chemical coprecipitation method and characterized by different methods. The synthesized magnetic composite was used as magnetic sorbent in dispersive solid phase extraction process for preconcentration of 4-tert octylphenol and atrazine. The experimental variables in dispersive solid phase extraction were optimized based on two strategies: one-factor-at-a-time for mixing type and buffer pH; Box Behnken design for sorbent amount, mixing period, eluent volume and buffer volume. Analysis of variance study for proposed model resulted to high determination coefficient (R2) of 0.957 and adjusted-R2 of 0.929 indicating a good adjustment of regression model with observed values. Under the optimum extraction conditions, the determination of analytes was carried out by a gas chromatography–mass spectrometry system. The limits of detection and quantification values under the optimum conditions were found to be 1.23 and 4.10 ng mL−1 for 4-tert octylphenol and 6.81 and 22.71 ng mL−1 for atrazine, respectively. The low relative standard deviation (≤ 6.2%) indicated good repeatability and satisfactory percent recovery values (96.3–112.6%) demonstrated the applicability of proposed method to tap water, river water and waste water samples.

Composite MOFs as adsorbents for solid phase extraction combined with high performance liquid chromatography for the determination of polycyclic aromatic hydrocarbons in water

Metal-organic frameworks (MOFs) are a kind of porous materials, which has large specific surface area, high porosity, diverse structure, excellent thermal stability and solvent stability etc. So, it has attracted extensive attention as an adsorbent for solid phase extraction (SPE). Polycyclic aromatic hydrocarbons (PAHs) are a kind of persistent organic pollutants that can lead serious hurts to the ecological environment and human health. The purpose of this paper is to optimize the types and proportion of mixed lanthanum based MOFs, and to improve the enrichment efficiency of SPE. Then a method to analysis PAHs by SPE-HPLC was established. Several main factors that could effected the pre-treatment efficient, such as the amount of adsorbent, the amount and pH of PAHs water sample, and the volume of eluent, were investigated. After optimized, the extraction of seven PAHs in water sample was achieved and the recovery rates were 80.67%, 80.06%, 54.69%, 82.62%, 118.87%, 70.30% and 95.57% respectively.

Synthesis, characterization and application of a new nano-structured samarium(III) ion-imprinted polymer

This work presents the synthesis of a new nano-structured samarium ion-imprinted polymer (Sm(III)-IIP) by precipitation polymerization. The Sm(III)-IIP nanoparticles were prepared by the copolymerization of Sm(III)–acrylic acid–4-vinylpyridine ternary complex with ethylene glycol dimethacrylate and methyl methacrylate, and then, Sm(III) was leached to obtain Sm(III)-IIP leached particles. Moreover, non-imprinted polymer particles were similarly prepared without Sm(III) ions. The characterization of polymers was carried out by Fourier transform IR spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), thermogravimetric analysis–differential scanning calorimetry (TGA–DSC) and surface analysis. The effect of several parameters such as solution’s pH, sorption and desorption time, type, concentration and volume of eluent on the extraction of the polymers was investigated and optimized by one variable at the time. Optimized parameters were as follows: pH 4; mass sorbent 0.1 g; sorption time, 120 min; desorption time, 120 min; aqueous phase volume, 10 mL. Moreover, it is found that 30 mL of HCl (3 M) provided the most effective elution of Sm3+ ion from IIP beads. The maximum sorbent capacity of the IIPs is 14.91 mg g−1. The sorbent was used for purification of samarium-152 stable isotope. The samarium-152 stable isotope recovery yield was % 99.67. The detection limit of the method was evaluated to be 0.27 ng mL−1. The precision of the method (%RSD, n = 6) was % 0.47.

DNA extraction from FFPE tissue samples - a comparison of three procedures.

Aim of the studyOne of the critical steps in molecular oncology diagnostics is obtaining high quality genomic DNA. Therefore, it is important to evaluate and compare the techniques used to extract DNA from tissue samples. Since formalin-fixed, paraffin-embedded (FFPE) tissues are routinely used for both retrospective and prospective studies, we compared three commercially available methods of nucleic acid extraction in terms of quantity and quality of isolated DNA.Material and methodsSlides prepared from 42 FFPE blocks were macro-dissected. Resulting material was divided and processed simultaneously using three extraction kits: QIAamp DNA FFPE Tissue Kit (QIAGEN), Cobas DNA Sample Preparation Kit (Roche Molecular Systems) and Maxwell 16 FFPE Plus LEV DNA Purification Kit (Promega). Subsequently, quantity and quality of obtained DNA samples were analysed spectrophotometrically (NanoDrop 2000, Thermo Scientific). Results of quantitative analysis were confirmed by a fluorometric procedure (Qubit 3.0 Fluorometer, Life Technologies).ResultsThe results demonstrated that the yields of total DNA extracted using either Maxwell or Cobas methods were significantly higher compared to the QIAamp method (p < 0.001). The Maxwell Extraction Kit delivered DNA samples of the highest quality (p < 0.01). However, the highest total yield of extracted DNA was achieved with the Cobas technique, which may be due to a higher volume of eluate compared to the Maxwell method.ConclusionsTo our knowledge, this is the first paper which directly compares three extraction methods: Cobas, Maxwell and QIAamp. The data herein provide information required for the selection of a protocol that best suits the needs of the overall study design in terms of the quantity and quality of the extracted DNA.

Trace determination and occurrence of eight chlorophenylacetonitriles: An emerging class of aromatic nitrogenous disinfection byproducts in drinking water

Two chlorophenylacetonitriles (CPANs) (2-chloro- and 3,4-dichlorophenylacetonitrile), representatives of an emerging class of aromatic nitrogenous disinfection byproducts, were recently identified in chlor(am)inated drinking water with liquid/liquid extraction and gas chromatography/mass spectrometry (GC/MS). Due to their high cytotoxicity, they are potentially significant drinking water contaminants. The detection limit for these two CPANs with the previous method was 100 ng L−1. To search for additional CPAN isomers, a more sensitive method for the simultaneous determination of eight CPANs was developed using solid-phase extraction (SPE)-GC/MS. GC/MS parameters and SPE pre-concentration conditions, including SPE cartridge, eluent type, eluent volume, and sample pH, were optimized. Under optimized conditions, the new method had method detection limits, method quantification limits, and precision ranging from 0.15 to 0.37 ng L−1, 0.50–0.95 ng L−1, and 5.8%–11%, respectively. The recoveries of the eight CPANs ranged from 92% to 102%. The concentrations of the eight CPANs in nine finished drinking waters were determined to be at concentrations ranging from 0.5 to 155 ng L−1. Seven CPANs were detectable in all samples. CPANs were detected at concentrations between 0.8 and 155 ng L−1 in chlorinated waters, and from 0.5 to 15 ng L−1 in chloraminated waters. Across all waters, the sum of all CPANs in chloraminated waters was 13% of that in chlorinated systems.

Fast determination of bisphenol A in spiked juice and drinking water samples by pipette tip solid phase extraction using cobalt metal organic framework as sorbent

A cobalt metal organic framework was prepared with rapid ultrasound assisted method by treatment of cobalt nitrate with pyridine 2,6-dicarboxilic acid dissolved in ethanolic media and used as a sorbent for pipette tip solid phase extraction of Bisphenol A (BPA) and its determination in spiked juice and drinking water samples by HPLC. Parameters which influence extraction efficiency such as pH, sample volume, amount of sorbent, type and volume of eluent, and number of draw/eject cycles for extraction and elusion were tested and optimized. Results showed that best extraction efficiency could be obtained at pH 3, 150 ‎µL of sample volume, 3 mg of adsorbent and 10 ‎µL of methanol as elution solvent. Numbers of draw/eject cycles for both sample extraction and elution were 7 cycles. Limit of detection and limit of quantification of this method were 0.07 and 0.3 µg L -1 , respectively, with linear dynamic range of 0.3 to 300 µg L -1 for BPA. This method was applied successfully for determination of BPA in five spiked juices and drinking water samples. KEY WORDS : Cobalt metal organic framework, Bisphenol A, Pipette-tip solid phase extraction, Juice analysis Bull. Chem. Soc. Ethiop. 2018 , 32(3), 595-602. DOI: https://dx.doi.org/10.4314/bcse.v32i3.17

Investigation and prediction of retention characteristics of imidazoline and serotonin receptor ligands and their related compounds on mixed-mode stationary phase

Investigation of the retention behavior of a wide range of analytes, 43 nitrogen containing heterocyclic and guanidine derivatives such, as imidazoline and serotonin receptor ligands or their related compounds, was performed on mixed-mode stationary phase in the combined reversed-phase (RP) and hydrophilic interaction liquid chromatography (HILIC) modes.Suitability of the linear retention modelling in the HILIC and RP modes was tested including separate contributions from adsorption and partition. For the HILIC retention, the partition model was found to provide better description compared with the adsorption model. In a wider range of the aqueous eluent volume fractions, φ(aq), retention was described as a function of volume fractions and total polarity of mobile phase using the mixed-mode retention modelling. The obtained results revealed that the shift of the chromatographic mode can be calculated from the change of total polarity of mobile phase in a multi-modal relation, logarithm of retention factor vs. total polarity, with the minimum value representing the turning point between the HILIC and the RP mode.Molecular properties of the investigated compounds that influence the retention behavior and the turning point were selected using Multiple Linear Regression (MLR) and Support Vector Machine (SVM). Slightly better statistical results were found for the logkwRP(aq)/MLR, logkwHILIC(org)/MLR, logkbHILIC(aq)/MLR, and φmin (aq)/SVM (RBF) QSRR models than for the logkwRP(aq)/SVM, logkwHILIC(org)/SVM, logkbHILIC(aq)/SVM, and φmin(aq)/MLR modelling. With this insight, it is possible to precisely define and predict the retention characteristics based on physico-chemical properties of imidazoline and piperazine related compounds.

Optimization of solid-phase extraction of parabens and benzophenones in water samples using a combination of Plakett-Burman and Box-Behnken designs.

An automated method for the analysis of methylparaben, propylparaben, benzophenone-3, and benzophenone-4 in water effluents via on-line solid-phase extraction coupled with high-performance liquid chromatography/ultraviolet detection was proposed. The preconcentration parameters were studied using Plackett-Burman and Box-Behnken experimental designs using a C18 sorbent material. The results demonstrated that the eluent volume, composition, and sorbent amount were statistically significant. Optimal conditions for these variables were an eluent volume of 1.55mL, eluent composition of acetonitrile 100% v/v, and sorbent amount of 100mg. The eluted sample was analyzed on-line using high-performance liquid chromatography equipped with a reversed-phase C18 column and ultraviolet detection. Separation of the analytes was achieved in 15min using gradient elution with acetonitrile/water. A simple, sensitive, and rapid analytical method was proposed for personal care compounds without sophisticated or expensive equipment. The limits of detection were 1.20, 1.73, 2.51, and 4.67μg/L for propylparaben, methylparaben, benzophenone-3, and benzophenone-4, respectively. The analysis time was 48min, consuming only 1.59mL of eluent acetonitrile for the solid phase extraction step, with minimal sample handling. The method was applied to the analysis of spiked swimming pool and wastewater, with recoveries between 65-107%. These results indicate the reliability of the flow-based procedure.

A simple liquid chromatography-high resolution mass spectrometry method for the determination of glyphosate and aminomethylphosphonic acid in human urine using cold-induced phase separation and hydrophilic pipette tip solid-phase extraction

Recently, the phenomenon of acute poisoning events caused by glyphosate (GLY) had frequently occurred all over the world. The present work reported a simple liquid chromatography-high resolution mass spectrometry (LC-HRMS) method for direct determination of GLY and its metabolite aminomethylphosphonic acid (AMPA) in human urine by combining cold-induced phase separation (CIPS) with hydrophilic pipette tip solid-phase extraction (PTSPE). First, a urine sample was mixed with acetonitrile at a 80% concentration to precipitate proteins. After centrifugation, the mixture was performed a CIPS at −20 °C to enrich GLY and AMPA (six-fold) in the lower water phase which was further performed PTSPE procedure. PTSPE as a miniaturized procedure of SPE, combined with a manual accu-jet® Pro Pipette Controller, was used to extract GLY and AMPA, in which a new type of hydrophilic adsorbent (HILIC powder) based on amide-modified silica was selected as the adsorption of GLY and AMPA. The key factors including the type and the amount of adsorbent, the loading extraction solution, the type and volume of eluent, and the number of aspirating/dispensing cycles were investigated in detail. Meanwhile, the selectivity and sensitivity of GLY and AMPA analysis were improved by the use of LC-HRMS based on targeted single ion monitoring (tSIM) mode without tedious derivatization. This method made a full use of the advantages of these techniques by combining efficient enrichment, effective extraction and selective separation in a simple way. Finally, a comprehensive validation of the method was rigorously executed and the results indicated that the validated method afforded desired linearity, precision, accuracy, and sensitivity.

Solid Phase Extraction of Cadmium and Lead from Water by Amberlyst 15 and Determination by Flame Atomic Absorption Spectrometry.

Preconcentration of Cd(II) and Pb(II) was carried out by using column solid phase extraction method. Amberlyst 15 was used as solid phase for these analytes. The optimum extraction conditions such as pH (4), type and volume of eluent (5mL of 2mol L-1 HNO3) sample flow rate (1mL min-1) and sample volume (100mL for Cd(II) and 750mL for Pb(II)) were determined. The recoveries were found for Cd(II) and Pb(II) as 104% ± 1% and 102 %± 2%, respectively. The limit of detections were found as 0.23µg L-1 for Cd(II) and 0.13µg L-1 for Pb(II). The effects of foreign ions were also studied. The method was validated by analyzing standard reference material and spiked water samples. Percent relative error and relative standard deviation were below 3% and 4%, respectively.

Detection of Bisphenol A in Water Samples by Magnetic Graphene Oxide Based Solid Phase Extraction and Liquid Chromatography

Bisphenol A (BPA) has received much attention from the public due to its endocrine disrupting effect. Therefore it is necessary to develop suitable analytical methods for determination of bisphenol A in water samples. In this study, magnetic graphene oxide was prepared and used as the sorbent for magnetic solid phase extraction of bisphenol A from aqueous solutions. The parameters which influence the extraction efficiency of bisphenol A were investigated. The optimum conditions, such as sample pH, extraction and desorption times, and eluent type and volume were obtained. The analytical performance of the method was evaluated, and the results showed that the limit of detection (LOD) for bisphenol A was 0.36μg/L and the RSD was 2.9 %. The developed method was applied to the detection of bisphenol A in environmental water samples with satisfactory recoveries.