Flow Injection Flame Atomic Absorption Spectrometry Research Articles

Novel determination of copper(II) in natural waters by solid-phase extraction (SPE) flow-injection (FI) flame atomic absorption spectrometry (FAAS)

A novel functionalized silica gel with the Schiff base of N-{[3-[(3-aminopropyl)amino]propyl}-2-hydroxy-benzaldimine was fabricated and utilized for flow-injection (FI) solid-phase extraction (SPE) of Cu(II) ions with flame atomic absorption spectrometric determination in environmental water samples. The practical factors on the FI-SPE of Cu(II) ions, including flow rates and volumes of sample and eluent solutions, eluent type and concentration, sample pH, and matrix ions, were studied. The maximum absorbance of Cu(II) ions was obtained using sample solutions at pH 7.0 at 5.0 mL min−1 with elution by 500 µL of 1.0 M HCl. Batch adsorption capacity of the functionalized silica gel for Cu(II) ions was 24.7 ± 0.3 mg g−1. The developed FI-SPE method was successfully validated by the determination of Cu(II) in water certified reference materials, including water-trace elements (NWTM-15.2) and Ontario Lake water (NWTMDA-54.4). Cu(II) levels in environmental samples such as tap, river, and sea water were successfully determined using the reported FI-SPE method.

Efficient lead preconcentration using two chemically functionalized carbon nanotubes in hyphenated flow injection-flame atomic absorption spectrometry system

Lead contamination in drinking and natural water has reached alarming concentrations, thus necessitating the development of accurate and rapid determination systems for Pb(II) in aqueous systems. Two hyphenated flow injection-solid phase extraction- FAAS (FI-SPE-FAAS) systems using oxidized and m-phenylenediamine functionalized multiwalled carbon nanotubes for Pb(II) preconcentration from industrially contaminated real water samples have been proposed. The chemical and hydrodynamic parameters affecting Pb(II) sorption/desorption were optimized. The effect of common interfering ions in water was also studied. Different figures of merit such as preconcentration factor (> 70), detection limit (≤ 1.5 µg L−1), and relative standard deviation (≤ 1.3%) were achieved at the preconcentration time of 120 s for both the preconcentration systems. The method was applied to industrially contaminated real water samples and the spike recovery tests were carried out using standard Pb(II) solution traceable to NIST. The proposed method was validated using standard reference material 1640a supplied by NIST Gaithersburg, MD, USA.

Comparative Insight into the Performance of Two Different Amine‐Functionalized CNTs for the Chemical Speciation of Chromium

AbstractPersistent industrial activities have led to an increase in the chromium content in environmental water bodies. The accurate quantification of trace chromium species such as Cr(III) and Cr(VI) is crucial as Cr(VI) can exhibit toxicity even at sub‐ppb levels. We report herein a comparative chromium speciation study using two chemically functionalized nanoadsorbents and determination with hyphenated flow injection‐flame atomic absorption spectrometry (FI‐FAAS). The most efficient preconcentration performance was obtained by optimizing the chemical and hydrodynamic parameters. Cr(VI) concentration was ascertained by the reduction to Cr(III) as the nanoadsorbents were selective for Cr(III) adsorption only; thus, speciation was achieved. The method was selective for Cr(III) in the presence of interfering matrix components. Preconcentration factor >90 and detection limit <0.11 μg L−1 were obtained for both the nanoadsorbents (%RSD∼1.0 %). The adsorption capacity of CNT‐TYR and CNT‐ASA was found to be 42.0 and 43.2 mg g−1, respectively. The application of the proposed method to contaminated water samples gave recoveries >95 %. The accuracy of the method was verified using NIST SRM 1640a.

Solidified floating organic drop microextraction for pre-concentration and trace monitoring of cadmium ions in environmental food and water samples

In this research, solidified floating organic drop microextraction as an efficient sample preparation method was used for trace monitoring of cadmium ions in environmental samples. In this method, a free microdroplet of 1-undecanol is floated on the surface of aqueous solution and agitated by a stirring bar placed on the bottom of the sample vial. Cadmium ions were complexed with neocuproine to obtain hydrophobic complex and extracted to extraction solvent. The extracted target ions were determined by flow injection–flame atomic absorption spectrometry. The effect of important factors on the extraction of target ions by the proposed sample preparation method was evaluated and optimized. The limit of detection, relative standard deviation (%) and enrichment factor of the method were 0.02, 3.7 and 98.5%, respectively. The validation of the method was examined by the analysis of cadmium ions in the certified reference material (sea food mix), and the obtained data can proof the reliability of the method for trace detection of cadmium ions. The method was successfully applied for determination of cadmium in the real food and water samples, and satisfactory relative recoveries (97–102%) were achieved.

Dispersive solid phase microextraction with magnetic graphene oxide as the sorbent for separation and preconcentration of ultra-trace amounts of gold ions

A selective, simple and rapid dispersive solid phase microextraction was developed using magnetic graphene oxide (MGO) as an efficient sorbent for the separation and preconcentration of gold ions. The MGO was synthesized by means of the simple one step chemical coprecipitation method, characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM). Gold ions retained by the sorbent were eluted using 0.5molL−1 thiourea in 0.1molL−1 HCl solution and determined by the flow injection flame atomic absorption spectrometry (FI-FAAS). The factors affecting the separation and preconcentration of gold were investigated and optimized. Under the optimized conditions, the method exhibited a linear dynamic range of 0.02–100.0µgL−1 with a detection limit of 4ngL−1 and an enrichment factor of 500. The relative standard deviations of 3.2% and 4.7% (n=6) were obtained at 20µgL−1 level of gold ions for the intra and the inter day analysis, respectively. The method was successfully applied to the determination of gold ions in water and waste water samples as well as a certified reference material (CCU-1b, copper flotation concentrate).

Development and evaluation of selective coating for stir bar sorptive extraction of silver using sol–gel technique in combination with double-imprinting concept

The flexibility and simplicity of stir bar sorption extraction (SBSE) have been combined with the selectivity of ion imprinted polymers (IIP) and a selective and fast extraction and preconcentration method for Ag(I) has been developed. The stir bar was coated with silver imprinted polymer using sol–gel technique in combination with double-imprinting concept. The retained silver was eluted with 250 µL thiourea solution (0.5 mol L−1) at a pH of 3.0–4.0 and was determined by flow injection-flame atomic absorption spectrometry. The factors affecting the separation and preconcentration of Ag(I) were optimized. Under the optimized conditions, the method exhibited a linear dynamic range of 0.5–50 µg L−1 with a detection limit of 0.04 µg L−1 and an enhancement factor of 196. A relative standard deviation of 3.2 % (n = 6) was obtained at the level of 20 µg L−1. The proposed method was successfully applied to the determination of silver in hair, nail and different water samples. The accuracy of the proposed procedure was verified by recovery experiments, independent analysis by electrothermal atomic absorption spectrometry (ET–AAS) and application of the method to the determination of silver in a certified reference material.

Separation/Preconcentration System Based on Emulsion-Induced Breaking Procedure for Determination of Cadmium in Edible Oil Samples by Flow Injection-Flame Atomic Absorption Spectrometry

In this work, a new procedure using extraction induced by emulsion breaking (EIEB) procedure has been developed for extraction/preconcentration of cadmium in various edible oils (canola, corn, hazelnut, olive, and sunflower oil) prior to its determination by flow injection (FI) flame atomic absorption spectrometry (FAAS). Five chemical variables (surfactant type, concentration of the surfactant, concentration of the nitric acid, emulsion breaking time, and temperature) were selected as the main factors affecting extraction efficiency, and two variables (sample flow rate and sample volume) were studied for optimizing flow injection conditions. The limits of detection of 1.53 and 1.55 μg L−1 were observed for cadmium when aqueous standard and oil-based standards were added to the samples for calibration, respectively. The linear range of cadmium in aqueous standard was varied in the range of 5.9–94 μg L−1. The precision of the EIEB procedure was obtained as 4.1 % by determination of ten replicates of 2.5 μg L−1 of cadmium, and the preconcentration factor 13.8 was obtained from only 4 mL of edible oil samples. The accuracy of the procedure was performed by comparison with the reference method based on the digestion of samples in a closed-vessel microwave oven and by spiking the samples with the known amounts of the cadmium in the form of oil-based standards. There were no statistical differences between the results obtained with the EIEB procedure and the reference microwave digestion method, and the recoveries were in the range of 97–104 %.

Homogeneous Liquid–Liquid Microextraction via Flotation Assistance with Thiol Group Chelating Reagents for Rapid and Efficient Determination of Cadmium(II) and Copper(II) Ions in Water Samples

In the present study, facile and competent homogeneous liquid–liquid microextraction via flotation assistance (HLLME-FA) method combined with flow injection flame atomic absorption spectrometry (FI-FAAS) was proposed for simultaneous separation/preconcentration and determination of trace amounts of cadmium and copper in water samples. The efficient 2-(3,4-dihydroxyphenyl)-1,3-dithiolane (DHPDTO) with thiol groups was used as chelating reagent. The predominant parameters influencing the HLLME-FA, such as solution pH, concentration of DHPDTO, extraction and homogeneous solvent types and volumes, ionic strength, and extraction time were studied. Applying all the optimum conditions in the process, the detection limits of 0.008 and 0.01 μg L−1, linear ranges of 0.08–40 and 0.1–45 μg L−1, and the precision (RSD%, n = 7) of 3.4 and 3.9 % were obtained, respectively, for cadmium and copper. The proposed procedure showed satisfactory results for analysis of tap water, river water, well water, and seawater.

Determination of zinc in edible oils by flow injection FAAS after extraction induced by emulsion breaking procedure

A new procedure using extraction induced by emulsion breaking (EIEB) procedure has been developed for extraction/preconcentration of zinc in various edible oils (canola oil, corn oil, hazelnut oil, olive oil, and sunflower oil) prior to its determination by the single line flow injection (FI) flame atomic absorption spectrometry (FAAS). Several parameters affecting the extraction efficiency of the procedure were investigated including the type and concentrations of surfactant, the concentration of HNO3, and the other operational conditions (emulsion breaking time and temperature). The limits of detection of 1.1 and 1.0μgL−1 were observed for zinc when aqueous standard and oil-based standards were added to the emulsions for calibration, respectively. The proposed procedure of combining EIEB and single line FI-FAAS can be regarded as a new procedure for the determination of zinc in edible oil samples.

On-line Preconcentration and Determination of Cd(II) in Water by Flow Injection-Flame Atomic Absorption Spectrometry (FI-FAAS) Using Salicylic Acid Functionalized Amberlite XAD-2 Resin-Packed Minicolumn

On-line Preconcentration and Determination of Cd(II) in Water by Flow Injection-Flame Atomic Absorption Spectrometry (FI-FAAS) Using Salicylic Acid Functionalized Amberlite XAD-2 Resin-Packed Minicolumn

Ligandless-solidified floating organic drop microextraction method for the preconcentration of trace amount of cadmium in water samples

In this article, a new ligandless solidified floating organic drop microextraction (LL-SFODME) method has been developed for preconcentration of trace amount of cadmium as a prior step to its determination by flow injection-flame atomic absorption spectrometry (FI-FAAS). The methodology is based on the SFODME of cadmium with 1-dodecanol in the absence of chelating agent. Several factors affecting the microextraction efficiency, such as, pH, sodium dodecylbenzenesulfonate (SDBS) concentration, extraction time, stirring rate and temperature were investigated and optimized. Under optimized experimental conditions an enhancement factor of 205 was obtained for 100mL of sample solution. The calibration graph was linear in the range of 1.0–25.0ngmL−1, the limit of detection (3s) was 0.21ngmL−1 and the limit of quantification (10s) was 0.62ngmL−1. The relative standard deviation (RSD) for 10 replicate measurements of 10ngmL−1 cadmium was 4.7%. The developed method was successfully applied to the extraction and determination of cadmium in standard and several water samples and satisfactory results were obtained.

Determination of copper traces in water samples by flow injection-flame atomic absorption spectrometry using a novel solidified floating organic drop microextraction method

A simple, rapid and inexpensive solidified floating organic drop microextraction (SFODME) and flow injection flame atomic absorption spectrometric determination (FI-FAAS) method for copper were developed. 3-amino-7-dimethylamino-2-methylphenazine (Neutral red, NR) was used as the complexing agent. Several factors affecting the microextraction efficiency, such as, pH, NR and sodium dodecylbenzenesulfonate (SDBS) concentration, extraction time, stirring rate, and temperature were investigated and optimized. Under optimized experimental conditions an enrichment factor of 541 was obtained for 100 mL of sample solution. The calibration graph was linear in the range of 0.5–20.0 ng mL − 1 and the limit of detection (3 s) was 0.18 ng mL − 1 , the limit of quantification (10 s) was 0.58 ng mL − 1 . The relative standard deviation (RSD) for 10 replicate measurements of 10 ng mL − 1 copper was 2.7%. The developed method was successfully applied to the extraction and determination of copper in different certified reference materials (Estuarine water, Slew 3 and fortified water, TM 23.2) and real water samples and satisfactory results were obtained.

Liquid carbon dioxide for improvements in online preconcentration and sample introduction in AAS,

In this work liquid carbon dioxide in a flow system for better sample introduction and online preconcentration of copper, by means of Thermospray Flame Furnace-Atomic Absorption Spectrometry (TS-FF-AAS) has been used. Liquid carbon was used as pressure pump, liquid carrier, eluting solvent and nebulizer gas in the flow system. The flow restrictor consisted of a fused silica capillary (optimal i.d. 75 μm, 5 cm length) which is used for maintaining carbon dioxide in liquid state under subcritical conditions (58.5 bar and room temperature). Regarding the aerosol formation mechanism by aqueous samples, the CO2-saturated sample is decompressed from 58.5 to 1 bar producing CO2 vaporization which expands the liquid jet and forms a conic wet aerosol cloud that is rapidly vaporized in the atomizer. In other cases, by elution of preconcentrated complexed metals from a column (C18), CO2-dissolved compounds became rapidly desolvated by CO2 vaporization, forming a dry aerosol of gaseous metal complexes which became thermally decomposed and atomized in the Ni-tube. The detection limit by means of liquid carbon dioxide have improved by a factor ca. 3 and 10, in comparison with TS-FF-AAS and Flow Injection Flame Atomic Absorption Spectrometry (FI-FAAS), respectively. Preconcentration of copper 8-hydroxyquinoleine complex in a C18 mini column and its elution with liquid carbon dioxide resulted in an enrichment factor of 24 and a detection limit of 2 μg L−1. This innovative system of sample pretreatment and nebulization envisages novel applications in atomic spectrometry avoiding the use of organic solvents and consequently the generation of toxic residues.

Selective cloud point extraction and preconcentration of trace amounts of cadmium prior to flame atomic absorption spectrometric determination

Cloud point extraction (CPE) is proposed as a separation and preconcentration procedure for determination of cadmium in water samples by flow injection flame atomic absorption spectrometry (FI-FAAS). The cadmium ion in aqueous solution was converted to [CdI4]2- and its charge was neutralized through ion-pair formation with methyltrioctylammonium cation in the presence of Triton X-114 as a non ionic surfactant. Phase separation was achieved by heating the mixture to 80 ºC for 10 min. The surfactant-rich phase was diluted with 300 µL of ethanol and 100 µL of it was analysed by FI-FAAS. The parameters affecting the ion-pair formation and extraction steps were optimized. Under optimum condition, preconcentration of 35 mL of sample in the presence of 0.04% (v/v) of Triton X- 114 led to a detection limit of 0.3 µg L-1 of Cd(II). Analytical calibration curve was linear up to 250 µg L-1 of cadmium and relative standard deviation was lower than 4% at 100 µg L-1 level. The procedure affords recoveries in the range of 95-102%. The procedure was successfully applied to the determination of Cd in tap water, sea water and certified reference copper concentrate.

On-line sorptive preconcentration platform incorporating a readily exchangeable Oasis HLB extraction micro-cartridge for trace cadmium and lead determination by flow injection–flame atomic absorption spectrometry

A simple, sensitive and inexpensive flow injection solid phase extraction (SPE) system was developed for automatic determination of trace level concentrations of metals. The potentials of this novel scheme, coupled to flame atomic absorption spectrometry (FAAS), were demonstrated for trace cadmium and lead determination in environmental water samples. The method was based on on-line chelate complex formation of target species with ammonium diethyldithiophosphate (DDTP), retention onto the surface of reversed-phase poly(divinylbenzene-N-vinylpyrrolidone) co-polymeric beads (Oasis HLB) and elution with methanol prior to atomization. A special PVC adapter was designed for easy and rapid replacement of the commercially available SPE cartridge. All main chemical and hydrodynamic parameters affecting the complex formation, sorption and elution of the analyte were optimized thoroughly. Moreover, the effect of potential interfering species occurring in environmental samples was also explored.For 90s preconcentration time, enhancement factors of 155 and 180, detection limits (3s) of 0.09μgL−1 and 0.9μgL−1 and relative standard deviations (R.S.D.) of 2.9% (at 4.0μgL−1) and 2.6% (at 20.0μgL−1) were obtained for cadmium and lead, respectively, with a sample throughput of 24h−1. The measurement trueness of the developed method was evaluated by analyzing a certified reference material and spiked environmental water samples. The proposed method is well suited to detect the target elements at concentration levels below the maximum allowed concentrations endorsed by the European Framework Directive (2008/105/EC) in inland and coastal waters.

On-line preconcentration and determination of nickel and zinc in natural water samples by flow injection–flame atomic absorption spectrometry using PTFE-turnings for column packing

A rapid, sensitive and low cost, time-based flow injection atomic absorption spectrometric method was described for the determination of nickel and zinc upon on-line preconcentration on a micro-column packed with polytetrafluoroethylene-turnings material. The metals formed on-line complexes with ammonium pyrrolidine dithiocarbamate from acidified solutions (pH 2.0) in the flow manifold and retained in the column. The preconcentrated elements were subsequently eluted quantitatively with isobutylmethylketone and injected directly into the nebuliser for atomisation and measurement. The system offered improved flexibility, low backpressure and applicability. The enhancement factors were 170 and 65 for Ni(II) and Zn(II), respectively. The respective detection limits were 0.5 and 0.3 µg L−1, and the precision, expressed as relative standard deviation, were 2.8% (at 5.0 µg L−1) and 3.2% (at 2.0 µg L−1), respectively. The accuracy of the developed method was sufficient and evaluated by the analysis of certified reference material and spiked environmental water samples.

A novel ionic liquid/micro-volume back extraction procedure combined with flame atomic absorption spectrometry for determination of trace nickel in samples of nutritional interest

A simple, highly sensitive and environment-friendly method for the determination of trace amount of nickel ion in different matrices is proposed. In the preconcentration step, the nickel from 10 mL of an aqueous solution was extracted into 500 microL of ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate [C(4)MIM][PF(6)], containing PAN as complexing agent. Subsequently, the PAN complex was back-extracted into 250 microL of nitric acid solution, and 100 microL of it was analyzed by flow injection flame atomic absorption spectrometry (FI-FAAS). The main parameter influencing the extraction and determination of nickel, such as pH, concentration of PAN, extraction time and temperature, ionic strength, and concentration of stripping acid solution, were optimized. An enhancement factor of 40.2 was achieved with 25 mL sample. The limit of detection (LOD) and quantification obtained under the optimum conditions were 12.5 and 41.0 microg L(-1), respectively. To validate the proposed methods two certified reference materials 681-I and BCR No. 288 were analyzed and the results were in good agreement with the certified values. The proposed method was successfully applied to determination of nickel in water samples, rice flour and black tea.

Separation/preconcentration and determination of cadmium ions by solidification of floating organic drop microextraction and FI-AAS

A simple and selective method for the separation and preconcentration of cadmium in water samples based on solidified floating organic drop microextraction (SFODME) was developed. The cadmium ion in aqueous solution was converted to CdI 4 2− and was then extracted with 160 μL of 1-undecanol containing cationic surfactant of methyltrioctylammonium chloride (0.2 mol/L). When the extraction was completed, 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. It was then diluted to 250 μL upon addition of ethanol, and 100 μL of it was analyzed by flow injection flame atomic absorption spectrometry (FI-FAAS). Factors that influence the extraction and ion pair formation, such as pH, concentration of iodide and methyltrioctylammonium chloride, extraction time, sample volume, and ionic strength were optimized. Under the optimized conditions, a preconcentration factor of 640, detection limit of 0.0079 μg/L and good relative standard deviation of ±5.4% at 5 μg/L were obtained. The procedure was applied to tap water, well water, and sea water; and accuracy was assessed through recovery experiment and independent analysis by graphite atomic absorption spectrometry. The accuracy was also evaluated through analyses of certified reference ore.

A Comparative Study of AgX (X = Cl−, Br−, I− and N3−) Solid-Phase Reactors for Flow-Injection Determination of Cyanide in Electroplating Wastewater

In this study, a rapid flow injection-flame atomic absorption spectrometry for cyanide detection was developed. Different AgX (where X is Cl(-), Br(-), I(-) and N(3)(-)) solid-phase reagents (SPR) were tested for indirect determination of cyanide. In a single-line FIA system, the cyanide was allowed to react with AgX SPR, which in turn changed Ag ions in AgX to silver cyanide complexes in a sodium hydroxide carrier stream. The eluent containing the analyte as silver cyanide complexes was measured by FAAS. The calibration curve was linear up to 30 mg l(-1) with a detection limit of 0.05 mg l(-1) for cyanides. The sampling rate and the relative standard deviation were <1.09% and >200 h(-1), respectively. The method was applied to the determination of cyanide in electroplating wastewater.

Speciation and determination of thallium by on-line microcolumn separation/preconcentration by flow injection–flame atomic absorption spectrometry using immobilized oxine as sorbent

A flow injection analysis (FIA) system incorporation a microcolumn of immobilized oxine on surfactant-coated alumina had been devised for performing rapid thallium enrichment/matrix removal in flame atomic absorption spectrometry (FAA). The preconcentration is based on the deposition of thallium(I) on microcolumn and subsequent elution with 500 microl of sodium thiosulfate (1 moll(-1)). In the presence of EDTA, only Tl(I) was retained on the microcolumn. Total thallium was determined after reduction of Tl(III) to Tl(I) by hydroxyl amine hydrochloride. A sample volume of 25 ml resulted in a preconcentration factor of 77. Precision at 30 microgl(-1) was 2.6% RSD (n=10). With 25 ml sampling volume a detection limit of 2.5 microgl(-1) was determined. The effect of potential interfering ions on the determination was studied. The method was applied for the determination of thallium in water, waste water, hair, nail, coal, and standard reference alloys. The accuracy was assessed through recovery experiment, independent analysis by Furnace-AAS, and analysis of certified reference alloys.