Flame Furnace Atomic Absorption Spectrometry Research Articles

Development of a novel direct magnetic sorbent sampling device by flame furnace atomic absorption spectrometry (DMSS-FF-AAS) using a carbonaceous nanocomposite for highly sensitive determination of cadmium

A novel and highly sensitive method for cadmium determination combining dispersive magnetic solid phase extraction (DMSPE), direct magnetic sorbent sampling (DMSS), and flame furnace atomic absorption spectrometry (FF-AAS) is described in this work.

On-line Micro-Packed Column Solid-Phase Extraction of Cadmium Using Metal-Organic Framework (MOF) UiO-66 with Posterior Determination by TS-FF-AAS

Metal-organic framework (MOF) UiO-66 was synthesized and evaluated as solid-phase extractor support for cadmium preconcentration in a micro-flow injection system coupled to thermospray flame furnace atomic absorption spectrometry (TS-FF-AAS) detection. The adsorbent was characterized by X-ray diffraction, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), Raman spectroscopy, and textural data from N2 adsorption/desorption isotherm data. The optimized conditions were achieved by loading 10.0 mL of a sample, containing 0.05 mol L-1 of phosphate buffer solution at pH 8.0, at a high flow rate of 10.0 mL-1 through 20.0 mg of UiO-66 packed into a mini-column, followed by elution with 1.0 mol L-1 HCl. At these conditions, the method presented a preconcentration factor of 35.7, limit of detection of 0.03 μg L-1 and a dynamic linear range from 0.1 to 8.0 μg L-1. The adsorption performance of UiO-66 towards cadmium was not influenced by Pb2+, Hg2+, Fe2+, Co2+, Cu2+, Ni2+, Zn2+, Mg2+ and Ca2+ ions. Analysis of different waters samples (tap water, physiological solution, mineral water, and lake water) was carried out without matrix interference, yielding recovery values ranging from 92.0 to 111.9%.

Microwave-Assisted Solid Sampling Analysis Coupled to Flame Furnace Atomic Absorption Spectrometry for Cd and Pb Determination in Food-Contact Polymers

Microwave-assisted solid sampling analysis coupled to flame furnace atomic absorption spectrometry (MW-SS-FF-AAS) was used for Cd and Pb determination in food-contact polymer samples, with the aim of minimizing reagents and laboratory waste. Operational parameters, such as the FF tube design, the oxygen flow rate, the flame stoichiometry, the sample mass, among others, were evaluated and optimized. Calibration was performed using only reference solutions, and the limits of quantification were 1.7 and 4.6 μg g−1 for Cd and Pb, respectively. Accuracy was assessed by the analysis of certified reference materials (CRMs), and by comparison with the results obtained by inductively coupled plasma mass spectrometry after microwave-assisted wet digestion. The MW-SS-FF-AAS results for the CRMs showed no statistical difference with the certified values, and good agreement was observed with the results of the digestion method. The MW-SS-FF-AAS method was considered suitable for Cd and Pb determination in food-contact polymers. The concentrations of Cd and Pb in the analyzed samples varied from <1.7 to 628 μg g−1, and from <4.6 to 614 μg g−1, respectively. As sample digestion is not necessary, the use of concentrated acids can be avoided by using the proposed MW-SS-FF-AAS method, greatly reducing waste generation.

Optimization of sample injection in TS-FF-AAS for determination of trace elements

In this work we present a proof of concept for the optimization of the analytical performance in ThermoSpray Flame Furnace Atomic Absorption Spectrometry (TS-FFAAS) by using different systems of sample injection. The influence of different operational variables was studied with emphasis on the characteristics of the ceramic capillary employed for sample introduction. The classic single hole capillary was compared to capillaries with different number of inner holes (one, four and six) and different spatial distribution. The influence on the analytical signal of a double simultaneous injection applied to different zones of the atomization furnace was also evaluated. Determination of elements with different atomization temperature (Ag, Cd and Se) was done, results shown an optimization of the figures of merit with respect to the TS-FF-AAS conventional assembly increased with the element volatility. Applications of Multi Injection (MI-TS-FF-AAS) was evaluated for determination of Cd in “yerba mate” samples; comparison of the obtained results using the proposed technique with other validated ones showed good agreement, and a reduction of amount of sample for the determination was achieved by using the multi-injection alternative. A discussion focused on the importance of an efficient sample introduction on the figures of merit attainable with TS-FFAAS and analytical applications of the technique is provided.

Investigation of thermospray flame furnace atomic absorption spectrometric determination of cadmium combined with ultrasound-assisted dispersive liquid-liquid microextraction

ABSTRACT Ultrasound-assisted dispersive liquid-liquid microextraction (UA-DLLME) was combined with thermospray flame furnace atomic absorption spectrometry (TS-FF-AAS) for the first time to develop a highly sensitive method for the determination of cadmium. Ultrasound was used to assist the liquid phase extraction, replacing the traditional disperser solvent. A self-assembled TS-FF-AAS instrument was adopted to improve the analytical performance of traditional flame atomic absorption spectrometry (FAAS), and the characteristic of micro-injection is fully suitable to be coupled with UA-DLLME. The developed combination significantly improved the analytical performance of TS-FF-AAS and traditional FAAS, while overcoming problems of nebulisation associated with the coupling of FAAS and liquid phase extraction methods. Some environmental water samples were collected and analysed by the developed coupling with satisfactory results.

Performance of Avocado Seed Activated Carbon as Adsorbent for Highly Sensitive Determination of Cd Using a Flow Injection System Online Coupled to TS-FF-AAS

A flow-injection preconcentration system using detection by the thermospray flame furnace atomic absorption spectrometry (FIA-TS-FF-AAS) is proposed. Cd2+ are adsorbed on avocado seed activated carbon (ASAC) packed into a cylindrical mini-column and eluted using HCl solutions for the detection system. A 25–1 fractional factorial and Doehlert matrix design were employed to determine the optimum conditions for cadmium preconcentration (pH 7.68, buffer concentration (Tris/Tris-HCl) of 0.023 mol L-1, eluent concentration (HCl) of 2.0 mol L-1, the adsorbent mass of 100.0 mg and preconcentration flow rate of 4.8 mL min-1). The preconcentration method presents linearity within the range of 0.41-15.00 µg L-1, limits of quantification and detection of 0.41 and 0.12 µg L-1, respectively, preconcentration factor of 10.7, consumption of index of 0.93 mL and sample throughput of 26 h-1. The precision assessed as the relative standard deviation (RSD) were found to be 0.48, 0.90 and 2.30% for inter-day precision (n = 2), and 0.30, 0.44 and 2.48% for intra-day precision (n = 6) for respective cadmium concentration of 0.50, 5.00 and 15.00 µg L-1. The proposed method was applied satisfactorily in samples of cigarette (62.84 ± 11.28 µg kg-1), human hair (69.61 ± 2.38 µg kg-1) and water samples [lake (0.65 ± 0.01 µg L-1), tap and mineral].

Investigation of dispersive solid-phase extraction combined with slurry sampling thermospray flame furnace atomic absorption spectrometry for the determination of cadmium

In this work, a sensitive method for the determination of cadmium by flame atomic absorption spectrometry (FAAS) was established by combining dispersive solid-phase extraction (DSPE) with thermospray flame furnace atomic absorption spectrometry (TS-FF-AAS). Nano-TiO2 was used as adsorbent, and the dispersive extraction simplified the operation procedure. Through the application of slurry sampling, the on-line combination of DSPE with TS-FF-AAS was established and the time-consuming elution step after DSPE was avoided. Problems of nebulization associated with previous methods based on the coupling of FAAS and SPE were overcome. DSPE combined with TS-FF-AAS significantly improved the analytical performance of the modified FAAS, which established a sensitive method for the determination of cadmium based on FAAS. Under the optimal conditions, the limit of detection (LOD) was 0.04 µg/L, which was better by an enhancement factor of 56. Compared to direct FAAS, the factor was 596. The method was applied to the determination of environmental water samples with satisfactory results.

Multivariate Statistical Characterisation of Soil Quality in the Lower Danube River Riparian Areas

Increasing anthropogenic influences on the environment has caused negative changes in natural ecosystems and soil contamination with potentially toxic metals has become a worrying issue at global level, due to the negative impact on the environment and human health. For the purpose of assessing soil contamination in the riparian areas of the Lower Danube River, a number of 144 soil samples were collected twice a year, in the period of June 2013 � December 2016, from 9 monitoring locations, from 0.05 m and 0.3 m depths, and the following indicators: Cr, Cu, Mn, Ni, Pb, Zn, including Ca, Mg, Corg, SO42- and humus content have been monitored. The soil was sampled, conserved and analysed according to the European standards in force. Metal concentrations were determined using flame (FAAS) and graphite furnace (GFAAS) atomic absorption spectrometry after �aqua regia� digestion of dried, homogenised and 0.5 mm sieved soil sub-samples. Comparing the average concentration values of the analysed potentially toxic metals, a decreasing tendency following the order Cr]Pb]Ni]Cu]Zn]Mn was observed and by reporting the average values at the normal limits, the order Zn]Cu]Mn]Ni]Pb]Cr of magnitude was obtained. To investigate possible correlations and interdependencies of potentially toxic metals content in the riparian soil, multivariate statistical methods were used. After applying Principal Component Analysis (PCA), 3 main components were identified, with a combined share of about 74 % of the original data-set variance. It was observed that during the monitoring period the average values of the all monitored elements from the studied soils were slightly below the normal reference values, according to the national legislation.

Microwave-assisted solid sampling system for Hg determination in polymeric samples using FF-AAS

In this work, a new portable device based on a monomode microwave applicator was developed and applied for microwave-assisted solid sampling analysis coupled to flame furnace atomic absorption spectrometry (MW-SS-FF-AAS). As an example of application, Hg was determined in polymer samples in order to demonstrate the feasibility of the proposed system. Polymeric samples were weighed directly on a quartz boat, containing a microcrystalline cellulose pellet wetted with 6 mol L−1 NH4NO3 solution, which was introduced into the microwave system for the combustion step. Oxygen flowed continuously through the quartz tube for sample combustion, as well as to carry the combustion products to the flame furnace (FF) atomizer. Microwave irradiation was kept on up to sample ignition (generally <5 s). After that, microwave was turned off and atomic absorption signals were integrated. The instrument calibration was possible using aqueous reference solutions after optimization of some operational conditions such as mass of combustion aid, volume of igniter, oxygen flow rate, FF tube design, flame stoichiometry, and sample mass. Under optimized conditions, the LOD and LOQ were 0.2 and 0.7 μg g−1, respectively, which were suitable for Hg determination at low concentration in polymers. In addition, no statistical difference was observed between the results obtained by MW-SS-FF-AAS and the certified values of certified reference materials (ERM EC 681k and ERM EC 680k). The proposed microwave-assisted solid sampling system is portable and might be easily adapted to any conventional atomic absorption spectrometer, increasing the range of applications of this well-known technique.

Development of carbon paste electrode modified with cadmium ion-imprinted polymer for selective voltammetric determination of Cd2+

ABSTRACTA simple and fast voltammetric method based on a new electrode composed of carbon paste electrode/bifunctional hybrid ion imprinted polymer (CPE/IIP) was developed for the quantification of Cd2+ in water samples. The voltammetric measurements by Differential Pulse Voltammetry were performed by using CPE containing 11.0 mg of IIP under phosphate buffer solution at concentration 0.1 mol L−1 and pH 6.5. The electrochemical method was carried out by Cd2+ preconcentration at −1.2 V during 210 s, followed by anodic stripping. The performance of IIP towards Cd2+ determination was evaluated by comparison to non-imprinted polymer, whose detectability of IIP was much higher (45%). The sensitivity of the sensor was found to be 0.0105 µA/µg L−1. The limits of detection and limits of quantification were found to be 4.95 μg L−1 and 16.4 μg L−1, respectively. The developed method was successfully applied to Cd2+ determination in mineral, tap and lake water samples, whose results are in agreement with thermospray flame furnace atomic absorption spectrometry (TS-FF-AAS) used as reference analytical technique. According to achieved results, the developed method can be used for routine analysis of quality control of water samples from different sources.

Application of thermospray flame furnace atomic absorption spectrometry for investigation of silver nanoparticles.

Thermospray flame furnace atomic absorption spectrometry (TS-FF-AAS) was applied to investigate the time-dependent absorption peak profile of various forms of silver. The thermospray flame furnace was set up with a 10-cm-long nickel tube with six holes, each 2.0mm in diameter, to allow the flame to enter, and this nickel tube acted as a furnace. A sample of 300μL was introduced into this furnace by use of water as a carrier at a flow rate of 0.5mLmin-1 through the ceramic capillary (0.5-mm inner diameter and 2.0-mm outer diameter), which was inserted into the front hole of the nickel tube. The system was applied to examine atomization behaviors of silver nanoparticles (AgNPs) with particle sizes ranging from 10 to 100nm. The atomization rate of AgNPs was faster than that of the dissolved silver ion. With increased amount of silver, the decay time observed from the time-dependent absorption peak profile was shortened in the case of dissolved silver ion, but it was increased in the case of AgNPs. With the particle size ranging from 10 to 100nm, the detection sensitivity was indirectly proportional to the particle size, suggesting that TS-FF-AAS may offer insights into the particle size of AgNPs provided that the concentration of the silver is known. To obtain quantitative information on AgNPs, acid dissolution of the particles was performed before TS-FF-AAS analysis, and recoveries of 80-110% were obtained.

Ion Imprinted Polymer for Preconcentration and Determination of Ultra-Trace Cadmium, Employing Flow Injection Analysis with Thermo Spray Flame Furnace Atomic Absorption Spectrometry.

This work proposes a preconcentration method using an ion imprinted polymer (IIP) for determination of cadmium, in several samples, employing a mini-column filled with the polymer coupled into a flow injection analysis system with detection by thermospray flame furnace atomic absorption spectrometry (FIA-TS-FF-AAS). The polymer was synthesized via bulk using methacrylic acid and vinylimidazole as a functional monomer. For the FIA system initial assessment, the variables: pH, eluent concentration and buffer concentration were studied, employing a 23 full factorial design. To obtain the optimum values for each significant variable, a Doehlert matrix was employed. After the optimization conditions as: pH 5.8, eluent (HNO3) concentration of 0.48 mol L-1 and buffer concentration of 0.01 mol L-1, were adopted. The proposed method showed a linear response in the range of 0.081-10.0 μg L-1, limits detection and quantification of 0.024 and 0.081 μg L-1, respectively; preconcentration factor of 165, consumptive index of 0.06 mL, concentration efficiency 132 min-1, and frequency of readings equal to 26 readings h-1 The accuracy was checked by analysis of certified reference materials for trace metals and recovery tests. The obtained results were in agreement with 95% confidence level (t-test). The method was adequate to apply in samples of: jewelry (earrings) (2.38 ± 0.28 μg kg-1), black tea (1.09 ± 0.15 μg kg-1), green tea (3.85 ± 0.13 μg kg-1), cigarette tobacco (38.27 ± 0.22 μg kg-1), and hair (0.35 ± 0.02 μg kg-1).

Development and feasibility of emulsion breaking method for the extraction of cadmium from omega-3 dietary supplements and determination by flow injection TS-FF-AAS

In the present study a new method for the determination of Cd2+ in omega-3 dietary supplement employing extraction induced by emulsion breaking (EIEB) and thermospray flame furnace atomic absorption spectrometry (TS-FF-AAS) was described. The method was based on the formation of a water-in-oil emulsion by the addition of extractor solution constituted by 3.54% (m/v) Triton X-114 and 1.16molL−1 HNO3 in the oil sample and further breaking of this emulsion by heating. Two well-defined phases were formed and the acid aqueous one containing the extracted cadmium ions was analyzed by TS-FF-AAS using a flow injection system. Different parameters that exert influence on the extraction efficiency of Cd2+ were optimized by means of chemometric tools. The limits of detection and quantification were found to be 2.5 and 8.3ngg−1, respectively using a calibration curve made in aqueous medium. The accuracy of the proposed method was assured by good agreement with the results achieved by microwave-assisted acid digestion procedure without statistical differences (confidence interval of 95%) and by spiking the samples with known concentrations of 50ngg−1 Cd2+. The content of Cd2+ in the samples was varied from 37.3 up to 54.5ngg−1.

A novel combination of experimental design and artificial neural networks as an analytical tool for improving performance in thermospray flame furnace atomic absorption spectrometry

In this work, we present the combined effect of artificial neural networks (ANN) and experimental design as a suitable analytical tool for improving the performance of thermospray flame furnace atomic absorption spectrometry (TS-FFAAS) using Mg as leading case.To this end, mixtures of different amounts of methanol, ethanol, and i-propanol in water were assayed as carriers at different flow rates and different flame stoichiometries (air/acetylene ratios). Different levels of these variables determined the experimental domain, consisting in a cube which was divided into eight identical cubical regions that allowed increase in the number of available experimental points. A Box–Behnken design (BBD) was employed in each one of the regions. The name Multiple Box–Behnken design (MBBD) was given to this new approach. Then, the features of ANN were exploited to find the optimum conditions for conducting Mg determination by TS-FFAAS.The prediction capability of ANN was examined and compared to the least-squares (LS) fitting when applied to the response surface method (RSM).The suitability of the new approach and the implications on TS-FFAAS analytical performance are discussed.

New subcritical fluid nebulizer (ScFN) for improving the determination of inorganic tin in gunshot residues by flame furnace-atomic absorption spectrometry

The determination of tin by FAAS is widely recognized as a difficult task in atomic spectrometry because of low sensitivity, poor detection limits and important interferences. In this work a new sample introduction system, the subcritical fluid nebulizer (ScFN) combined with the flame furnace-atomic absorption spectrometry (FF-AAS) was applied for improving the determination of inorganic tin in aqueous solutions. Online preconcentration of tin as Sn-PDC complex was carried out in a HPLC-guard cartridge (5mm length, 2mm diameter) filled with C-18 coated monolithic silica having an absorption capacity of 2.5μg of tin. For preconcentration optimized conditions were achieved at 0.015% (m/v) of APDC and pH5 obtaining a preconcentration factor of 17 using 2.5mL of sample volume. The elution was done by means of subcritical liquid carbon dioxide and methanol with a flow rate of 1.5Lmin−1 which was directly introduced as a dry aerosol into the flame furnace where tin complexes are vaporized and atomized. Applying ScFN-FF-AAS the detection and quantification limits for tin in water were 0.008mgL−1 and 0.024mgL−1, respectively, increasing the power of detection in 325 times compared to the conventional detection limits obtained by flame atomic absorption spectrometry. The precision at 1mgL−1 was 1.5% expressed as RSD (N=10). Tin was determined in samples of gunshot residues generated by firing four ammunition brands. The concentrations fluctuated between 52 and 151μgL−1.

Direct extraction of lead (II) from untreated human blood serum using restricted access carbon nanotubes and its determination by atomic absorption spectrometry

Oxidized carbon nanotubes were covered with layers of bovine serum albumin to result in so-called restricted-access carbon nanotubes (RACNTs). This material can extract Pb2+ ions directly from untreated human blood serum while excluding all the serum proteins. The RACNTs have a protein exclusion capacity of almost 100% and a maximum Pb2+ adsorption capacity of 34.5mgg−1. High resolution transmission electron microscopy, scanning transmission electron microscopy and energy dispersive spectroscopy were used to confirm the BSA layer and Pb2+ adsorption sites. A mini-column filled with RACNTs was used in an on-line solid phase extraction system coupled to a thermospray flame furnace atomic absorption spectrometry. At optimized experimental conditions, the method has a detection limit as low as 2.1µgL−1, an enrichment factor of 5.5, and inter- and intra-day precisions (expressed as relative standard deviation) of <8.1%. Recoveries of the Pb2+ spiked samples ranged from 89.4% to 107.3% for the extraction from untreated human blood serum.

ELEMENTOS-TRAÇO EM ÁREAS DE VEGETAÇÃO NATIVA E AGRICULTURA INTENSIVA DO ESTADO DE MATO GROSSO DETERMINADOS POR FLUORESCÊNCIA DE RAIOS-X POR REFLEXÃO TOTAL

A espectroscopia de raios-X por reflexão total (TXRF) é uma técnica promissora para análise de elementos-traço (ETs), principalmente por não ser necessária a digestão das amostras, reduzindo assim a geração de resíduos e emissão de vapores tóxicos. Este trabalho comparou os teores dos ETs: Cr, Mn, Ni, Zn, Cu, As, Se, Hg e Pb, coletados em solos de área de agricultura intensiva e vegetação nativa, determinados por TXRF e por espectrometria de absorção atômica de chama ou forno de grafite (FAAS/GFAAS). Adicionalmente, compararam-se os teores dos ET com valores de referência para solos não contaminados. As amostras de solo foram coletadas na profundidade 0,0-0,2 m em municípios representativos de cada região agrícola do Estado de Mato Grosso (Rondonópolis, Alto Garça, Primavera do Leste, Campo Novo, Nova Mutum, Lucas do Rio Verde, Sorriso, Sinop, Campo Novo dos Parecis, Campos de Julho e Vila Bela da Santíssima Trindade). Em cada município, foram selecionadas seis áreas, totalizando 72 amostras, todas georreferenciadas. Para a leitura dos teores de ET no aparelho de TXRF S2 Picofox™, foram preparadas suspensões de solo usando Triton X-100 a 5 % v/v utilizando gálio como padrão interno, enquanto no FAAS/GFAAS as amostras foram submetidas à digestão ácida pelo método 3051A. Considerando área cultivada e área nativa, respectivamente, os teores médios dos ET por TXRF, em mg kg-1, foram: Cr, 69 e 62; Zn, 16 e 8; Pb, 28 e 21; Mn, 56 e 42; As, 2 e 2; Cu, 9 e 8; e Ni, 2 e 2. O Cd, Se e Hg não foram detectados por TXRF nas amostras analisadas. Para As, Cr, Mn, Zn, Ni, Cu e Pb, houve correlação linear (p&lt;0,001) positiva entre as técnicas e, no geral, os teores obtidos para esses ET em TXRF foram superiores aos do FAAS/GFAAS. Os teores de todos os elementos detectados pelo TXRF, exceto o Cr, estão dentro das faixas dos relatados para solos não contaminados e muito inferiores aos limites de alerta estipulados na literatura.

Interference-free Determination of Pb in Complicated Matrices by Displacement-Cloud Point Extraction Coupled With Thermospray Flame Furnace Atomic Absorption Spectrometry

Interference-free Determination of Pb in Complicated Matrices by Displacement-Cloud Point Extraction Coupled With Thermospray Flame Furnace Atomic Absorption Spectrometry

Towards broadening thermospray flame furnace atomic absorption spectrometry: Influence of organic solvents on the analytical signal of magnesium

This study demonstrates the influence of the solvent when thermospray flame furnace atomic absorption spectrometry (TS-FF-AAS) is employed for the determination of elements of low volatility, taking magnesium (Mg) as leading case. Several organic solvents/water solutions of different characteristics (density, surface tension, viscosity, etc.) and proportions were employed for the TS-FF-AAS analytical determination. To this end, solutions containing methanol, ethanol and isopropanol in water were assayed. Measurements were performed at different acetylene/air ratios of the combustion flame and then, the corresponding response surfaces were obtained. Methanol/water 75% v/v as carrier and a fuel rich flame were found as the most sensitive alternative.In the light of these findings and in order to explain the changes on the analytical signal, the influence of the solvent characteristics, the sample droplet size and the redox environment was studied. An estimation of the temperature of different zones of the heated flame furnace based on a modified signal ratio pyrometry method was analyzed for comparative purposes. A full discussion is provided throughout the paper.Once obtained the best conditions for analysis, Mg was determined in samples of effervescent vitamin tablets comparing two different solvents. The tablets were dissolved in methanol/water 75% v/v and ethanol/water 75% v/v and then, directly introduced in the TS device. The methanol/water 75% v/v dissolution yielded a slightly higher sensitivity when compared to ethanol/water and thus, the latter was selected due to its lower toxicity. The obtained figures of merit are: LOD (3σb): 0.021mgL−1; LOQ (10σb): 0.068mgL−1, sensitivity: 0.086Lmg−1; RSD%: 3.55, dynamic linear range 0.068–5mgL−1. Comparison of the results was performed by flame atomic absorption spectrometry (FAAS), showing a good agreement (95% confidence level, n=5). Whilst the FAAS approach needed sample mineralization as no complete solubility was attained with both alcohol/water solvents, TS allowed direct introduction of the sample with an excellent recovery of the analyte after spiking. The whole TS procedure was more economic (lower amount of reagents and wastings, lower time of operation) and faster (60h−1 sampling throughput) than FAAS.Nonetheless, the main objective of this work is to show that an analytical signal different from zero can be obtained for Mg via TS by simply choosing the adequate operational variables that allow an optimization of the mass transfer of the analyte into the atomizer and a favorable dynamics of desolvation/atomization.This approach could broad TS analytical capabilities to other elements of lower volatility as it is shown here for the case of Mg.

Cadmium and Lead Determination in Freshwater and Hemodialysis Solutions by Thermospray Flame Furnace Atomic Absorption Spectrometry Following Cloud Point Extraction

Cloud point extraction was employed for the separation and preconcentration of cadmium and lead prior to the determination by thermospray flame atomic absorption spectrometry. Di-2- pyridyl ketone salicyloylhydrazone (DPKSH) was used as complexing agent and the cadmium and lead complexes were extracted from the aqueous phase by the Triton X-114 surfactant. The variables associated with the preconcentration (pH as well as DPKSH, surfactant and electrolyte concentration) were optimized by using a full factorial design with two levels, four variables and a central composite. Under the optimized conditions, a sample volume of 100 µL was introduced into a hot Ti tube at a flow rate of 0.6 mL min-1 and the integrated absorbance was measured. Calibration curves were obtained with linear ranges of 0.075-2.0 µg L−1 (Cd) and 2.5-100 µg L−1 (Pb). The detection limits of 0.04 µg L−1 (Cd) and 1.3 µg L−1 (Pb) (99.7% confidence level) were obtained. The proposed method was applied to hemodialysis solutions and water samples. The accuracy of the method was evaluated by analyzing a certified reference material (NIST CRM 1643e) and the results were in agreement with the certified values at a 95% confidence level according to t-test.