Flow injection micelle-mediated methodology for determination of lead by electrothermal atomic absorption spectrometry

A simple and sensitive flow injection micelle-mediated method was developed for the determination of trace Pb by electrothermal atomic absorption spectrometric (ET-AAS). The formation of the analyte-entrapped surfactant micelles by online merging of the analyte solution with O,O-diethyldithiophosphate solution and Triton X-114 solution sequentially, the adsorption of the resultant analyte-entrapped surfactant micelles onto a microcolumn packed with silica gel. The adsorbed analyte was then eluted with methanol and determined by ET-AAS. With consumption of 6.0 mL sample solution, a detection limit of 0.016 μg L⁻¹, and a concentration factor of 21.6 were obtained at a sample throughput of 20 h⁻¹. The relative standard deviation was 5.1% (c = 2.0 ng mL⁻¹, n = 7). The method has been successfully applied to the analysis of trace Pb in water sample with recoveries ranging from 94.0 to 99.0%. The certified reference material was also analyzed for validation, and the determined value obtained was in good agreement with the certified value.     

Flow injection ion-exchange preconcentration for the determination of iron(II) with chemiluminescence detection

Summary Flow injection analysis with on-line ion-exchange preconcentration using a mini-column loaded with 8-quinolinol immobilized on controlled-pore glass, is described for the determination of iron(II)-enhanced chemiluminescent oxidation of luminol in alkaline hydrogen peroxide. The detection limit for iron(II) is 10^–13 mol/l (in 3 ml of sample). The operating conditions are optimized, and the effect of interferents is studied. The analysis time was 5 min for each sample, including 2 min for sample loading.     

Flow injection techniques for flame atomic absorption spectrophotometry

When analysing real samples by flame atomic absorption spectrophotometry, considerable sample pretreatment together with the selection of the correct calibration strategy is necessary to ensure accurate results. Flow injection techniques can be used (a) to improve existing procedures, (b) as the basis for new calibration methods, and (c) to extend the capabilities of conventional flame atomic absorption spectrophotometry.     

Flow injection and microwave-oven sample decomposition for determination of copper,zinc and iron in whole blood by atomic absorption spectrometry

A simple and rapid method is proposed for the determination of copper, zinc and iron in whole blood. The injected sample is mineralized in the flow system on passage through a microwve oven and the metals are determined by atomic absorption spectrometry. Prior sample destruction or removal of organic material prior to injection is not necessary. The required volumes for each analysis are 90, 60 and 100 μl for copper, zinc and iron, respectively. The relative standard deviations were less than 3% in all cases. There was good agreement between the results obtained with the flow-injection method and those attained by conventional spectrophotometric measurements.     

Spectrophotometric determination of iron(III) and total iron by sequential injection analysis technique

A procedure for determination of concentrations of iron(III) and total iron by sequential injection analysis is described. The method is based on the strong blue-colored complexes formed between iron(III) and tiron. The absorbance of the complexes is measured spectrophotometrically at 635 nm. Oxidation of iron(II) and masking of interfering fluoride is simultaneously done by injecting one zone of hydrogen peroxide and one of thorium(IV) between the sample and reagent zones. Concentration of iron(III) and total iron, in the range 0.002–0.026 M, in diluted samples from a pickle bath were determined. The relative standard deviation was 0.4% (n=7). The method was also used in a pilot plant of a zinc process for determination of iron(III) in the range 0.2–3.0 g l⁻¹. The sample throughput is approximately 17 samples per hour, including three repetitive determinations of each sample.     

Flow injection system for atomic absorption spectrometry

A manifold is described which permits the analysis of less than 1 ml of sample solution. Water- and air-compensation methods for the introduction of the carrier stream into the nebulizer are effective in obtaining sensitive and reproducible measurements of magnesium, but air-compensation gives higher peak responses.     

Simultaneous determination of iron(II), iron(III), and titanium(IV) by flow injection analysis using kinetic spectrophotometry with Tiron

Summary Two flow injection analysis systems have been worked out for the simultaneous determination of Fe(III), Fe(II), and Ti(IV) based on the kinetic spectrophotometry with Tiron. The first system uses a silver reductor column and a single detector with two flow cells aligned in the same optical path to yield two peaks corresponding to (a) Ti(IV)-Tiron and (b) Ti(IV) plus total iron(III)-Tiron complexes. An another sample injection without the silver column yields a single peak which corresponds to Ti(IV) plus Fe(III)-Tiron complexes. With the two sample aliquot injections the system permits simultaneous determinations with throughput of 30 samples/h in the g to several tens g range of each species. The second system is a multidetection system with or without the silver reductor column using the same spectrophotometry with Tiron, in which the entrapment of the sample plug into a closed system allows its repetitive passage through a single detector. With the advantage of much simpler instrumentation, the system permits 6 samples/h to be analyzed for the three metal species with somewhat lower precisions than the first system.     

Simultaneous determination of iron(II) and iron(III) in aqueous solution by kinetic spectrophotometry with tiron

A kinetic spectrophotometric method that requires no prior measurement of rate constants is developed for the simultaneous determination of iron(II) and iron(III). The method is based on the aerial oxidation of iron(II) in the presence of tiron and acetate ions. The iron(III) formed is subsequently complexed with tiron and the absorbance/time relation is evaluated. The concentrations of iron(III) and iron(II) are obtained from the absorbance values at the start and at equilibrium, respectively, calculated by non-linear least-squares fitting. A linear calibration graph is obtained up to 12 μg ml^?1 iron(II)/iron(III). The method is applied to iron-rich ground water.     

流动注射光度法测定痕量铁

水 乙醇混溶介质中Fe(Ⅲ)与2 (5 溴 2 吡啶偶氮) 5 二乙氨基苯酚(5 Br PADAP)的显色反应已有用于流动注射的报道[1 2],本文利用稀盐酸的增敏作用,在较低的显色剂浓度和乙醇用量条件下,无需加入乳化剂增溶,采用显色剂与缓冲溶液预先混合,以去离子水为推动液,用正交设计法优化各实验参数,优选出了最佳的组合方案。该方法的线性范围为20μg/L-1200μg/L,相对标准偏差为0 5%。将该方法用于水样实际测定,效果满意。方法的检测限优于已有的报道。1　实验部分1 1　主要仪器与试剂ZJ 2低压过渡金属离子色谱仪(将分离柱用聚四氟乙烯管代替,…     

Flow injection calibration methods for atomic absorption spectrometry

The use of an atomic absorption spectrometer as a detector in flow injection analysis is briefly reviewed. A new simplified model is described for the dispersion effects observed with such systems; the model is based on considering the dispersion to be due to a single hypothetical mixing chamber located immediately prior to the measurement stage. The utility of this approach is demonstrated for two methods of calibration commonly used in atomic absorption spectrometry, and it is shown that flow injection sample and standard handling techniques are comparable to manipulation with volumetric apparatus. The flow injection method has a number of advantages for the analogue of the standard addition method. The use of an exponential concentration gradient is proposed as a novel method of calibration using a single concentrated standard. Results are presented for the determination of chromium in standard steels.     

The determination of iron in tungsten carbide by atomic absorption spectrophotometry

An atomic absorption spectrophotometric procedure for the determination of 0.005 to 0.20% iron in a phosphoric acid solution of tungsten carbide is described. The method is rapid, preliminary separations are not required and the results obtained have been compared with those obtained by X-ray fluorescence.     

The determination of manganese in iron and steel by atomic absorption spectrophotometry

A procedure is described for the determination of 0.001–2% of manganese in low and high alloy irons and steels by atomic absorption spertrophotometry. The sample is dissolved in phosphoric-sulphuric acid and atomised in an atomic absorption spectrophotometer. The method is rapid, free from interferences, preliminary separations are not required and results obtained on standard samples agree closely with stated certificate values.     

Ultra-trace determination of Pb(II) and Cd(II) in drinking water and alcoholic beverages using homogeneous liquid-liquid extraction followed by flame atomic absorption spectrometry

The determination of Pb(II) and Cd(II) in different sample matrices, including drinking water, distilled spirits and fruit wine, was carried out by flame atomic absorption spectrometry (FAAS) after pre-concentration using homogeneous liquid-liquid extraction (HLLE). First, the HLLE method was optimised with lead diethyldithiocarbamate (Pb-DDTC) complex which was extracted with a perfluorooctanoate anion (PFOA^?) dissolved in lithium hydroxide under acidic conditions. The optimum extraction conditions, using 0.01 M DDTC, 0.05 M PFOA^?, 3 M HCl and 1 mL of 30 vol. % acetone, were obtained. The Pb-DDTC complex in the nitric acid digest of the samples (50–150 mL) was extracted quantitatively into a drop of 100 μL of sediment phase. The sediment phase dissolved in 1 vol. % HNO₃ with at least 3–5 mL of the final volume was then determined by FAAS, affording a pre-concentration factor of 10–50. Hence, the HLLE method afforded an increase in both sensitivity and selectivity for the metal determination by conventional FAAS, resulting in ultra-trace level detection of Pb(II) in all samples analysed (drinking water, 9.2–23 ng mL^?1; distilled spirits, 23–50 ng mL^?1; fruit wine, 24–53 ng mL^?1). In addition, the proposed method could successfully be applied to Cd(II) determination in these samples.     

Cloud point extraction of aluminum (III) in water samples and determination by electrothermal atomic absorption spectrometry,flame atomic absorption spectrometry and UV-visible spectrophotometry

Cloud point extraction was applied as a preconcentration step for the determination of trace level of Al(III) in water samples with electrothermal atomic absorption spectrometry (ETAAS), flame atomic absorption spectrometry (FAAS) and UV-visible spectrophotometry. The aluminum was extracted as aluminum-Eriochrome Cyanine R (ECR) complex, at pH 6 by micelles of the non-ionic surfactant octylphenoxypolyethoxyethanol (Triton X-114). The investigations showed that the same CPE procedure can be used for different detection techniques. The results obtained from these techniques were evaluated. Under the optimal conditions, limit of detection obtained with ETAAS, FAAS and UV-visible spectrophotometry were 0.03 ng mL^?1, 0.06 µg mL^?1 and 0.01 µg mL^?1, respectively. The accuracy of the procedure was tested by analysing certified reference material. The method was successfully applied to determination of aluminum in water samples and dialysis fluid.     

Synthesis of polyaniline-coated titanium oxide nanoparticles for preconcentration of cobalt (II) followed by electrothermal atomic absorption spectrometry

Journal of the Iranian Chemical Society - An efficient and novel adsorbent, polyaniline (PANI)-coated titanium oxide nanoparticle (TiO2-NPs) was applied for preconcentration of ultra-trace levels...     

Speciation of iron (II) and (III) by using solvent extraction and flame atomic absorption spectrometry

A method for speciation, preconcentration and separation of Fe²⁺ and Fe³⁺ in different matrices was developed using solvent extraction and flame atomic absorption spectrometry. PAN as complexing reagent for Fe²⁺ and chloroform as organic solvent were used. The complex of Fe²⁺-PAN was extracted into chloroform phase in the pH range of 0.75-4.0 and Fe³⁺ remains in water phase in the pH range 0.75-1.25. The optimum conditions for maximum recovery of Fe²⁺ and minimum recovery of Fe³⁺ were determined as pH = 1, the stirring time of 20 min, the PAN amount of 0.5 mg and chloroform volume of 8 mL. The developed method was applied to the determination of Fe²⁺ and Fe³⁺ in tea infusion, fruit juice, cola and pekmez. It is seen that there is high bioavailable iron (Fe²⁺) in pekmez. The developed method is sensitive, simple and need the shorter time in comparison with other similar studies.     

Flow-injection determination of iron(II), iron(III) and total iron with chemiluminescence detection

Iron(II) (1.0 × 10^?9–1.0 × 10^?6 M) is determined by the production of chemiluminescence in a luminol system in the absence of added oxidant. Iron(III) (2.0 × 10.8^?8–2.0 × 10^?6 M) is determined after reduction to iron(II) in a silver reductor mini-column in the flow system. Cobalt, chromium, copper and manganese interfere.     

Simultaneous determination of iron(III) and cobalt(II) withN-phenylcinnamohydroxamic acid and thiocyanate by extraction and spectrophotometry

Simple, precise, sensitive, and highly selective methods for the separate determination of iron(III) and cobalt(II) and for the simultaneous determination of both metal ions are described. Iron(III) and cobalt(II) react with thiocyanate in the presence ofN-phenylcinnamohydroxamic acid (PCHA) to form pinkish red and blue coloured complexes, respectively. Both the iron(III) and cobalt(II) complexes having stoichiometric composition of 122 (FeSCN^–PCHA) and 14 (CoSCN^–), respectively, are quantitatively extractable into ethylacetate from 0.5–1.5 M hydrochloric acid solutions. The spectra of iron(III) and cobalt(II) complexes in the visible region exhibit absorption maxima at 495 and 625 nm, respectively. The coloured systems obey Beer's law in the concentration range of 0.2–4.0g/ml of iron and 2–40g/ml of cobalt. The effects of foreign ions and of various experimental parameters were studied to establish the optimum conditions for the extraction and determination of iron and cobalt. The methods have been applied successfully to the analysis of blood, vitamin B₁₂, and standard steels for iron and cobalt.     

Flow injection determination of Pb and Cd traces with graphite furnace atomic absorption spectrometry

The preconcentration and recovery of lead and cadmium traces at ng l(-1) level were evaluated in standard solutions and natural aqueous samples using a FIAS (Flow Injection Atomic Spectrometry) apparatus. The method is based on retention of the complex formed between Pb or Cd and 1,2-dihydroxy-3,5-benzendisulphonic acid (Tiron) on a macroporous anion-exchange resin. The recovery of the analytes was obtained by elution with 0.1 M HCl and their determination was performed by Graphite Furnace Atomic Absorption Spectrometry (GFAAS). The detection limits were 9 and 7 ng l(-1) for Pb and Cd respectively. The effects of sample solution pH and composition and of interfering agents as well as reagent purity are discussed. The technique was applied to the analysis of natural waters.     

Preconcentration and atomic absorption determination of iron by sequential injection analysis

A sequential injection analysis (SIA) assembly for the atomic absorption determination of Fe(III) in natural waters is proposed. Iron is preconcentrated on a microcolumn packed with a chelating resin (Chelex 100) that is inserted in the manifold. The sample is passed through the column and the iron retained by the resin is subsequently eluted with 2 M HNO(3). The proposed SIA system affords automatic preconcentration, elution, detection of Fe(III), data acquisition and treatment. When 9 ml of iron solution containing 0.4 or 1 mg l(-1) was passed through the resin, the retention efficiency was 93.1 +/- 0.6 and 7.4 +/- 3.0% respectively, and when 27 ml of iron solution of 0.2 mg l(-1) was preconcentrated, the retention was 8.4 +/- 2.9%. The detection limits thus achieved is 12 mug l(-1) when 9 ml of sample are preconcentrated and 6 mug l(-1) for 27 ml.