Determination of iron and lead by flame atomic absorption spectrometry after preconcentration with sepiolite

By using a new adsorbent (sepiolite) an adsorption-elution and atomic absorption spectrometric method has been developed for the preconcentration and determination of Fe and Pb. Recoveries of the analytes were 82 ± 3% for Fe and 91 ± 2% for Pb at 95% confidence level. For Cu it was only 5 ± 1%. The recovery of iron could be increased to about 97 ± 1% by complexing with EDTA, the recovery of copper only to 57 ± 2%. The optimised method was applied to the determination of lead in metal materials (e.g. brass). Received: 20 February 1996 / Revised: 7 May 1996 / Accepted: 11 May 1996     

Determination of Cu, Zn, Fe, Ni and Cd by flame atomic absorption spectrophotometry after preconcentration by Escherichia coli immobilized on sepiolite

A method for the determination of Cu, Zn, Fe, Ni and Cd by flame atomic absorption spectrophotometry (FAAS) after preconcentrating on a column containing Escherichia coli immobilized on sepiolite has been developed. Optimum pH values, amount of adsorbent, elution solution and flow rate have been obtained for the elements studied. The effect of interfering ions on the recovery of the analytes has also been investigated. Recoveries of Cu, Zn, Fe, Ni and Cd by E. coli immobilized on sepiolite were 99.1+/-0.6, 98.2+/-0.6, 98.1+/-0.5, 97.2+/-0.8 and 98.2+/-0.4% at 95% confidence level, respectively. The adsorption capacity of E. coli immobilized on sepiolite was found as 0.148, 0.064, 0.098, 0.134 and 0.088 mmol/g for Cu, Zn, Fe, Ni and Cd, respectively. The proposed method was applied to the determination of trace metals in alloys (NBS SRM 85b). Trace metals have been determined with relative error lower than 10%.     

Determination of selenium in a nickel alloy by flame atomic absorption spectrometry after electrochemical preconcentration

The nickel alloy is dissolved in nitric/hydrochloric/phosphoric acid mixture, and selenium is electrodeposited onto a platinum loop at ?0.4 V (vs. Ag/AgCl). Selenium is atomized from the electrode in an argon/hydrogen flame with simultaneous electrothermal heating of the loop. For the NBS standard nickel-based high-temperature alloy (SRM 899), the mean value found was 9.7 μg g^?1 with a standard deviation of 0.4 μg g^?1 (certified value 9.5 ± 0.1).     

火焰原子吸收法测定铬质引流砂中铁镁含量

建立了火焰原子吸收光谱法连续测定铬质引流砂中铁、镁含量的分析方法。试样以碳酸钠-硼酸混合熔剂熔融,以盐酸浸取,在校准溶液中加入重铬酸钾和二氧化硅进行基体匹配,抵消基体影响。对熔剂、熔融温度等进行讨论,确立了最佳分析条件,对样品多次测定,其测定结果与国家标准测定方法测定的结果基本一致,相对标准偏差(RSD,n=11)小于0.3%,加标回收率在98.7%~101%。方法具有操作简便、准确性好、速度快、成本低等特点。     

Determination of some trace elements by flame atomic absorption spectrometry after preconcentration and separation by Escherichia coli immobilized on multiwalled carbon nanotubes

We have immobilized living and non-living Escherichia coli (E. coli) bacteria on multiwalled carbon nanotubes (MWCNT) and used such materials as a biosorbent for the separation and preconcentration of copper, cobalt, cadmium and nickel prior to their determination by flame atomic absorption spectrometry (FAAS). E. coli bacteria cells were mixed with MWCNTs in a 1:1 ratio, dried and placed at the tip of a 50-mL syringe. The ions were retained on the sorbent and then eluted by drawing and ejecting back the sample (or standard solution) and an eluent, respectively. The effects of various experimental parameters on the sorption and elution were investigated. The analytes were quantitatively retained (at pH values of 7) and eluted (with 0.5 M nitric acid) with high precision, the RSD being <5%. The performances of the new sorbents were compared using certified reference materials. The sorbent modified with living E. coli has a higher adsorption capacity and displays somewhat better recoveries compared to sorbent based on non-living E. coli. Both sorbents were successfully used for the separation and preconcentration of copper, cobalt, cadmium and nickel prior to their determination by flame atomic absorption spectrometry.

Determination of magnesium in iron by atomic absorption spectrophotometry

An atomic absorption spectrophotometric method for the determination of 0.001–0.10% magnesium in irons has been proposed. After suitable dissolution of the sample, 1500 p.p.m. of strontium is added to suppress aluminium interference and the solution is atomised in an atomic absorption spectrophotometer. The method is rapid, has high sensitivity, is free from interference and no preliminary separations are required.     

Determination of lead in preserved egg by flame atomic absorption spectrometry after chemically modified preconcentration

A sensitive method for the determination of lead in preserved egg by flame absorption spectrometry using ammonium pyrrolidine dithiocarbamate-polystyrene chemically modified platinum wire matrix is presented. The modified platinum wire matrix, after preconcentrating the lead, is placed in a flame burner for direct atomization and measurement. The concentration range is linear between 5 and 500 ng/ml lead in solution and the detection limit is 0.65 ng/ml. This new technique is sensitive and convenient.     

Determination of selenium in technical sulphuric acid by flame atomic absorption spectrometry after electrochemical preconcentration

Electrochemical preconcentration on a platinum filament, followed by atomization in an argon—hydrogen flame with simultaneous electrothermal heating of the filament, is used for the determination of selenium in technical sulphuric acid. The effect of experimental parameters such as acid concentration, deposition potential and temperature are described, and the speciation of selenium in sulphuric acid is discussed. The technical acids were found to contain selenium in the range 30–60 μg l^-1.     

Determination of beryllium in solid samples by flame atomic absorption spectrometry after preconcentration on activated carbon.

It is generally supposed that the preconcentration procedure is used for the determination of metal concentrations under the sensitivity of the measurement method. This study showed that preconcentration is also need for the beryllium (Be) concentration over the sensitivity of atomic absorption spectrometry. For this purpose, a simple and selective method for the determination of Be in solid samples is modified. The method is based on the preconcentration of the complexes of beryllium-acetylacetone plus morin, oxine, PAN and PAR on activated carbon at different pH values. The adsorbed beryllium was eluted with aqua regia and measured by flame atomic absorption spectrometry (FAAS). Recoveries of up to 85% were achieved. For removing chemical interferences and applying the method to Be determination in solid samples, the masking studies and reproducibility were examined. The detection limit was found to be 0.12 ng mL(-1). The relative sandard deviations (RSD) were found to be 8% for 60 mL of 10.0 ng mL(-1) using 10 replicate enrichment procedures. Beryllium concentrations in the studied solid samples were found in the range of 0.28 - 3.95 mg kg(-1).     

Determination of wear metals in lubricating oils by flame atomic absorption spectrophotometry

A simple, rapid and reliable method was developed for the determination of copper, nickel, iron and lead in fresh and used lubricating oil samples by flame atomic absorption spectrophotometry (FAAS). In the present study, a mixture of organic solvents containing propionic acid and iso-butylmethyl ketone (1: 1) was used to extract the metals from lubricating oil samples followed by FAAS analysis. Aqueous standard solutions can be easily employed with the proposed mixed solvent system instead of organometallic standards. The analytical results obtained by employing the proposed solvent extraction system were found to be in good agreement with the results for aqueous media obtained after the destruction of oil samples matrix. Percentage recovery studies showed 88–98% for Cu, 92–95% for Fe, 96–106% for Ni and 84–100% for Pb with relative standard deviation of 2–6%. The developed method was effectively applied to routine determination of Cu, Ni, Fe, and Pb in lubricating oil samples.     

Determination of trace cadmium in waters by flame atomic absorption spectrophotometry after preconcentration with 1-nitroso-2-naphthol-3,6-disulfonic acid on Ambersorb 572

A procedure for the determination of trace amount of cadmium after adsorption of its 1-nitroso-2-naphthol-3,6-disulfonic acid chelate on Ambersorb 572 has been proposed. This chelate is adsorbed on the adsorbent in the pH range 3-8 from large volumes of aqueous solution of water samples with a preconcentration factor of 200. After being sorbed, cadmium was eluted by 5 mL of 2.0 mol L(-1) nitric acid solution and determined directly by flame atomic absorption spectrophotometery (FAAS). The detection limit (3sigma) of cadmium was 0.32 microg L(-1). The precision of the proposed procedure, calculated as the relative standard deviation of recovery in sample solution (100 mL) containing 5 microg of cadmium was satisfactory (1.9%). The adsorption of cadmium onto adsorbent can formally be described by a Langmuir equation with a maximum adsorption capacity of 19.6 mg g(-1) and a binding constant of 6.5 x 10(-3) L mg(-1). Various parameters, such as the effect of pH and the interference of a number of metal ions on the determination of cadmium, have been studied in detail to optimize the conditions for the preconcentration and determination of cadmium in water samples. This procedure was applied to the determination of cadmium in tap and river water samples.     

交联壳聚糖分离富集-火焰原子吸收法测定水样中痕量银

以甲醛、环硫氯丙烷为交联剂,由壳聚糖合成了一种新型的交联壳聚糖微球(FCCIS)分离树脂,研究了不同条件下FCCTS对Ag(Ⅰ)的吸附性能.在pH 3.6时FCCTS对Ag(Ⅰ)定量吸附,吸附在树脂上的Ag(Ⅰ)可用0.5 moL/L的氨水将其洗脱,用火焰原子吸收光谱测定.该法对Ag(Ⅰ)的检出限为61 ng/mL(3σ,n=8),相对标准偏差为2.2%(n=7,ρ=2μg/mL),线性范围为0.05～4μg/mL,加标回收率在98.8%～101.7%之间.该法已用于水样中痕量银测定.     

脉冲进样火焰原子吸收光谱法测定血清、脑和骨中的铁

采用脉冲微量进样火焰原子吸收光谱法测定血清、脑组织及骨中铁含量。血清样品经稀释后直接测定，脑组织及骨样品采用HNO3－HClO4湿法消化。实验探讨了进样体积、提升速度等影响因素，方法的相对标准偏差为1．1％－3．3％，平均回收率为99．0％－100．1％。     

Determination of lithium in sea water by atomic absorption and by flame emission spectrophotometry

Summary Comparison of two instrumental methods for the analysis of lithium in sea water showed that both atomic absorption and flame emission spectrophotometry can be used without pretreatment of the sample. The interference of the other constituents of sea water in the analysis has been studied. Calibrations using an artificial sea water or the standard addition method may be used.

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Zusammenfassung Ein Vergleich der beiden Methoden hat gezeigt, daß zur Analyse von Lithium im Meerwasser sowohl die Atomabsorptionsspektrophotometrie, als auch die Flammenspektrophotometrie ohne Vorbehandlung der Probe angewendet werden können. Der Einfluß der anderen Bestandteile des Meerwassers auf die Analyse wurde untersucht. Für die Eichung des Verfahrens wurde künstliches Meerwasser sowie die Methode des Standardzusatzes verwendet.

     

Dithizone immobilized silica gel on-line preconcentration of trace copper with detection by flame atomic absorption spectrometry

A novel adsorbent-silica gel bound dithizone (H₂Dz-SG) was prepared and used as solid-phase extraction of copper from complex matrix. The H₂Dz-SG is investigated by means of FT-IR spectra and the SEM images, demonstrating the bonding of dithizone. The H₂Dz-SG quantitatively adsorb copper ions, and the retained copper is afterwards collected by elution of 10% (v/v) nitric acid. An on-line flow injection solid-phase extraction procedure was developed for trace copper separation and preconcentration with detection by flame atomic spectrometry. By loading 5.4 mL of sample solution, a liner range of 0.5-120 μg L⁻¹, an enrichment factor of 42.6, a detection limit of 0.2 μg L⁻¹ and a precision of 1.7% RSD at the 40 μg L⁻¹ level (n = 11) were obtained, along with a sampling frequency of 47 h⁻¹. The dynamic sorption capacity of H₂Dz-SG to Cu²⁺ was 0.76 mg g⁻¹. The accuracy of the proposed procedure was evaluated by determination of copper in reference water sample. The potential applications of the procedure for extraction of trace copper were successfully accomplished in water samples (tap, rain, snow, sea and river). The spiking recoveries within 91-107% are achieved.