Rapid and simple chromatographic separation of V(V) and V(IV) using KH-phthalate and their determination by flame atomic absorption spectrometry

A method was developed for the chromatographic separation of V(V) and V(IV) based on the different sorption forces of these vanadium species in C18 columns in presence of KH-phthalate. The vanadium species were detected with a flame atomic absorption spectrometer with acetylene/N₂O flame. The detection limits (3σ) of V(V) and V(IV) were 0.18 μg/mL and 0.15 μg/mL, respectively. The relative standard deviations (N = 5) are 4.2% and 3.4% for 20–20 μg/mL V(V) and V(IV), respectively. The sampling frequency is 75/h. Because of the special interaction occurring between phthalate and V(IV) on the C18 column and the acetylene/N₂O flame atomic absorption detection, practically no interferences can be detected even in large inorganic matrix.     

A surface ion-imprinted mesoporous sorbent for separation and determination of Pb(II) ion by flame atomic absorption spectrometry

A surface-imprinted mesoporous sorbent for Pb(II) ion was synthesized by the post-synthesis method. The material was characterized by transmission electron microscopy and nitrogen adsorption-desorption isotherms. The adsorption by the material was studied by batch experiments with respect to effects of pH value, contact time, kinetics, and adsorption isotherms. Both the pseudo-second-order kinetic model and the Langmuir model fit the experimental data well. Compared to other imprints for Pb(II), to the traditional sorbents and to the non-imprinted polymer, the new sorbent displays fast kinetics and higher selectivity. Pb(II) ion can be desorbed from the imprint with 2 M hydrochloric acid with high efficiency. The sorbent was applied to the selective separation and determination of Pb(II) in water and sediment samples with satisfactory results.

Preconcentrative separation of chromium(III) species from chromium(VI) by cloud point extraction and determination by flame atomic absorption spectrometry

Microchimica Acta - We describe a high-throughput technique for the determination of chromium species in water samples by flame atomic absorption spectrometry (FAAS) after preconcentrative...     

Speciation analysis of inorganic vanadium (V(IV)/V(V)) by graphite furnace atomic absorption spectrometry following ion-exchange separation

A sensitive and simple method of ion-exchange resin separation and graphite-furnace atomic absorption spectrometry (GFAAS) detection was proposed for the determination of inorganic vanadium species. Methylene Blue (MB) was used as a chelating agent of V(V) for ion-exchange separation. The complex of V(V) and MB could be trapped by ion-exchange resin at pH 3.0 and eluted by 1.0?mol?L^?1 NaOH. The vanadium species was determined subsequently by GFAAS. The concentration of V(IV) was calculated by subtracting the V(V) concentration from the total concentration of vanadium. Under the optimized experimental conditions, the detection limit of V(V) is 0.48?µg?L^?1 with RSD of 2.6% (n?=?5, c?=?2.0?µg?L^?1). In order to verify the accuracy of the method, a certified reference soil sample was analyzed, and the results obtained were in good agreement with the certified values. The range of recovery for V(IV) and V(V) was 97.8–99.3% and 101.7–103.6%, respectively. The proposed method was applied to the speciation analysis of vanadium in lake-water samples.     

Separation and preconcentration of Pb(II) using ionic liquid-modified silica and its determination by flame atomic absorption spectrometry

A new method based on microcolumn packed with ionic liquid-modified silica combined with flame atomic absorption spectrometry has been developed for the determination of lead in environmental samples. Several factors influencing the preconcentration efficiency of lead and its subsequent determination, such as pH of the sample, flow rate, mass of ionic liquid, and interfering effect, have been investigated. Lead could be quantitatively retained by ionic liquid-modified silica in the pH range of 5-7, and then eluted completely with 3.0 mL 1.0 mol L⁻¹ HCl. The detection limit of this method for lead was 0.7 μg L⁻¹ with preconcentration factor of 185, and the relative standard deviation (RSD) was 4.2% at 0.1 μg mL⁻¹ Pb(II). This method has been applied for the determination of trace amount of lead in NIST standard reference material 2709 (San Joaquin Soil) and river water samples with satisfactory results.     

Indirect flow-injection determination of ascorbic acid by flame atomic absorption spectrometry

A continuous-flow procedure is proposed for the indirect determination of ascorbic acid, based on its reducing properties because of the oxidation of its 1,2-enediol group. Iron(III) was injected into a 1,10-phenanthroline stream, which was mixed with a sample carrier and then with a sodium picrate solution stream. In these conditions the iron(III) was reduced to iron(II) by the ascorbic acid. Thus, the iron(II) formed reacts with 1,10-phenanthroline to form a charged red complex, which with picrate ion forms a stable red-orange uncharged ion-association complex that is adsorbed on-line on a non-ionic polymeric adsorbent (Amberlite XAD-4), proportionally to the ascorbic acid in the sample. The unadsorbed iron was determined by flame atomic absorption spectrometry. The proposed method allows the determination of ascorbic acid in the range 0.5–25 g ml^–1 with a relative standard deviation of 2.9% at a rate of ca. 90 samples h^–1. This method has been applied to the determination of ascorbic acid in pharmaceutical preparations, fruit juices and sweets. The results obtained in the analysis are compared with those provided by the 2,6-dichloroindophenol method.     

火焰原子吸收光谱法间接测定药剂中的核黄素

本文利用高碘酸钠对相邻羟基氧化作用的专属性,在一定介质中,高碘酸钠与核黄素完全反应后,过量的高碘酸的钠与硝酸铅或者硝酸铜生成沉淀,通过测定Pb<'2+>或者Cu<'2+>,建立了间接测定核黄素含量的方法.铅体系和铜体系测定的相对标准偏差(RSD)分别为4.8%和5.2%,检出限分别为0.6μg.mL<'-1>和0.5μ...     

Silicon determination in Portland cement by fluoride generation,using flame atomic absorption spectrometry

A new method for the determination of silicon in Portland cement, based on the generation of volatile species without sample pre-treatment, is proposed. The method reduces operational complexity and time without loss of precision and with similar accuracy as the current methods. It employs microwave-assisted (domestic microwave oven) digestion to produce volatile silicon fluorides by reaction of the sample with a fluorinated salt (CaF₂) in the presence of H₂SO₄ (98% w/w), using a Teflon® (PFA) reactor. The volatile fluorides are flushed out by a dry nitrogen stream and collected in 0.3 mol l⁻¹ NaOH solution where they dissolve. Silicon is determined in this solution by flame atomic absorption spectrometry (FAAS). The recoveries are between 98 and 102%, and the precision is better than 2.5% relative standard deviation (R.S.D).     

Preconcentration of trace metals with 2-(methylthio)aniline-functionalized XAD-2 and their determination by flame atomic absorption spectrometry

2-(Methylthio)aniline-modified Amberlite XAD-2 has been synthesized by coupling it through a NNNH group. The resulting chelating resin, characterized by elemental analysis, thermogravimetric analysis and infrared spectra, was used to preconcentrate Cd, Hg, Ni, Co, Cu and Zn ions. Several parameters, such as the distribution coefficient and sorption capacity of the chelating resin, pH and flow rates of uptake and stripping, and volume of sample and eluent, were evaluated. The effect of electrolytes and cations on the preconcentration was also investigated. The recoveries were >96%. The procedure was validated by standard addition and analysis of a standard river sediment material (GBW 08301, China). The developed method was utilized for preconcentration and determination of Cd, Hg, Ni, Co, Cu and Zn in tap water and river water samples by flame atomic absorption spectrometry with satisfactory results. The 3σ detection limit and 10σ quantification limit for Cd, Hg, Ni, Co, Cu and Zn were found to be 0.022, 0.028, 0.033, 0.045, 0.041, 0.064 μg l⁻¹ and 0.041, 0.043, 0.052, 0.064, 0.058, 0.083 μg l⁻¹, respectively.     

Rapid and simple method for the determination of copper, manganese and zinc in rat liver by direct flame atomic absorption spectrometry.

An acidic homogenate method, which includes simple homogenization pre-treatment of tissue material and direct nebulization flame atomic absorption spectrometry (FAAS), is successfully applied to the simultaneous determination of copper, manganese and zinc in rat liver. The proposed method involves only a few steps for sample pre-treatment at room temperature, making the risk of systematic errors very small. Because recoveries of 101% for copper, 98% for manganese and 100% for zinc could be achieved using aqueous standards, matrix-matched standards were redundant. Favourable results obtained in biological media, including limits of detection of 0.04, 0.03 and 0.04 mg l-1 for Cu, Mn and Zn, respectively, together with accuracies of 0-3%, and relative standard deviations ranging from 2 to 10% are further evidence of the suitability of the method.     

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.     

Preconcentration and determination of trace metals by flow injection micelle-mediated extraction using flame atomic absorption spectrometry

Micelle-mediated extraction/preconcentration is incorporated on-line into a flow injection system used to determine low levels of Cd(II), Co(II), Cu(II), Mn(II), Ni(II), Pb(II) and Zn(II) present in various samples. The analyte is complexed with HBDAP (N,N′-bis(2-hydroxy-5-bromo-benzyl)1,2-diaminopropane). Under optimal conditions, a solution of 30% (m/v) NaCl and a sample solution containing 2.5 mL of 1% (m/v) sodium dodecyl sulfate (SDS), 0.5 mL of 1.8 × 10⁻³ M HBDAP and 2.5 mL of pH 8.5 borate buffer solution in 25 mL were pumped through the cotton filled mini-column; onto which the surfactant-rich phase containing the complex is collected. A solution of 0.5 M HNO₃ in 50% acetone is used as the eluent. The limits of detection are (ng mL⁻¹) Cd = 0.39, Cu = 3.2, Co = 7.5, Mn = 3.0, Ni = 3.4, Pb = 17.9 and Zn = 0.89 if the sample is allowed to flow for 30 s, but improved for extended preconcentration periods. Analysis of liquid and solid reference materials showed good agreement with the certified values. Complex formation constants between HBDAP and these metal ions were also determined potentiometrically.     

On-line determination of trace levels of palladium by flame atomic absorption spectrometry

A preconcentration method is developed for the on-line determination of palladium in complex matrices with flame atomic absorption spectrometry (FAAS). The flow system comprised of a minicolumn filled with polyamine Metalfix-Chelamine resin which is highly selective for Pt(IV), Au(III) and Pd(II). Best preconcentration conditions are established by testing different resin quantities, sample and eluent solution volumes, and adsorption and elution steps flow rates. Sample volumes of 4.7 ml of palladium solutions resulted in an enrichment factor of twenty at the optimum hydrodynamic conditions. This value can be increased by injecting larger volumes of sample solution. The method is sensitive, easy to operate and permitted the determination of sub-mg l⁻¹ levels of palladium with a detection limit of 0.009 mg l⁻¹. The resin was used up to 60 times in consecutive retention-elution cycles without any appreciable deterioration in its performance. The applicability of this method was tested by determining the palladium content in synthetic geological samples as well as in the pellet-type used car catalyst reference material.     

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.     

Rapid determination of lead in steel by flameless atomic absorption spectrometry

A method for the determination of 1–100 p.p.m. of lead in high- and low-alloy steels by flameless atomic absorption is described. The sample was dissolved in aqua regia. and 2 μl of the diluted solution were pipetted into a Massmann-type furnace. Ashing of the sample at 625°C eliminated influences from hydrochloric acid. Fe, Cr and Ni gave similar negative interferences, which were compensated for by using low-alloy steel with standard additions. An interlaboratory comparison showed that this method gave the same result as extraction with TOPO in MIBK. The procedure could also be applied to commercial instruments. The time for a complete analysis including dissolution was 15 min.     

Monitoring of V(IV) and V(V) in Etnean drinking-water distribution systems by solid phase extraction and electrothermal atomic absorption spectrometry

Monitoring activities carried out since 1994 showed the presence of significant levels of vanadium in drinking waters delivered in a lot of Etnean towns. The highest vanadium concentration was found in ground waters collected in the drainage gallery Ciapparazzo located on the Northwestern flank of Mt. Etna in Bronte's area (Catania, Italy). This drainage gallery, with a flow rate of near 500 l s^− 1, is an important water source for several towns of the Etnean province. On account of different toxicological behaviours of V(IV) and V(V), which are the only possible oxidation states in aqueous media, a research project was set up to evaluate the ratio between their concentrations before and after disinfection treatments (chlorination or UV irradiation). Data were acquired in the most representative sites of the drainage gallery and the distribution network to evaluate the effect of residence times and disinfection treatments on possible species interconversion. The average total concentration of vanadium was 165 μg l^− 1. Speciation analyses performed by solid phase extraction of both species followed by furnace atomic absorption spectrometric determination of V(IV) eluates revealed that the latter was the predominant species (90-100%) in untreated waters. Moreover, among the two disinfecting treatments applied by the water supplier, only sodium hypochlorite altered the species ratio and determined an instant increase of near 20% in V(V) relative concentration. No significant effect was observed as residence time varied in the drainage gallery or in the distribution systems. Other physico-chemical and chemical parameters (i.e. pH, E_H, water temperature, electrical conductance, dissolved oxygen as well as major and minor inorganic cations and anions) were determined in the collected water samples to evaluate if they are proper or not for interconversion of the two V species. Redox potential of the water was also correlated to the percentage of V(IV).     

流动注射在线三正辛胺萃淋树脂分离富集火焰原子吸收法测定银

使用填充三正辛胺（TOA）萃淋树脂的微型柱，采用流动注射在线分离富集与火焰子吸收法联用技术，对微量银的测定进行了研究。在1．0mol/L HCl介质中样品流速为8．1mL/min，采样60s，以0．25mol/L HCl-0.5mol/L硫脲洗脱。在30样／h的分析速度下，富集倍率为26倍，富集效率为26／min，消耗指数为0．31mL。线性范围为0－1000μg/L，检出限为1．2μg/L。银含量为50μg／L时，连续11次测定的相对标准偏差为1．4％。对铅锌冶炼矿渣样液进行加标回收率试验，回收率为91．1％－100．6％，并应用于测定光谱纯氧化镁中的微量银。     

火焰原子吸收光谱法测定冰晶石中的铁

建立了火焰原子吸收光谱法测定冰晶石中铁的分析方法。样品用高氯酸溶解后,在0.48mol/L的盐酸介质中用空气-乙炔火焰测定了样品中的铁,测定结果与有色金属行业标准方法(邻二氮杂菲光度法)的分析结果一致。检出限为0.004 11mg/L,相对标准偏差(RSD)为0.95%~4.5%,加标回收率为98.00%~101.49%。     

Preconcentration and separation of traces of mercury by reduction of metallic copper and determination by atomic absorption spectrometry without flame]

A micro-column of copper can be used to separate quantitatively as little as 5 ng of mercury from small volumes of solution. For large volumes, e.g. 500 ml, separation depends on the flow rate and on adsorption phenomena; the latter effect can be overcome by addition ofcomplexing agents. The mercury amalgamated on copper is determined directly by non-flame atomic absorption spectrometry. The limit of determination is 1–2 ng. The method is faster and more selective than preconcentration by electrolysis.     

Copper determination in sugar cane spirits by fast sequential flame atomic absorption spectrometry using internal standardization

In this study, a fast and simple method is proposed for the determination of Cu in sugar cane spirits employing fast sequential flame atomic absorption spectrometry and the internal standard technique. First, Ag, Bi, Co and Ni were evaluated as internal standards to minimize transport interferences. The results demonstrated that Ag at a concentration of 2 mg L^− 1 was effective. Under these conditions, Cu could be determined with a limit of detection of 15 µg L^− 1. Then, Cu was determined in 5 sugar cane spirit samples using the proposed method and the results were compared with those obtained by inductively coupled plasma optical emission spectrometry after microwave oven acid digestion. The content of Cu varied from 0.66 to 6.64 mg L^− 1. Accuracy and precision of the proposed method were evaluated by comparing the results obtained with both methods. A paired t-test at a 95% confidence level showed that the proposed method enabled the achievement of similar results as those obtained by ICP OES after acid digestion.