Improvement of copper FAAS determination conditions via preconcentration procedure with the use of salicylaldoxime complex trapped in polymer matrix (original) (raw)
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Talanta, 2008
A new Cu(II)-imprinted polymer (Cu-IIP) for preconcentration of copper by liquid-solid extraction via flow injection technique has been proposed. Cu-IIP was obtained by copolymerization of salen-Cu(II) complex with styrene and divinylbenzene using suspension polymerization technique. Granules fraction of 60-80 m in diameter was used as a microcolumn packing. Cu(II) sorption was proved to be the most effective from solutions of pH 7, whereas similar elution effectiveness was observed when applying as eluents hydrochloric or nitric acid in the concentration range of 0.5-10% (v/v). The system exhibited good long-term stability and acid resistance. Batch sorbent capacity was found to be 0.11 mmol g −1 of a dry polymer. Enrichment factor (EF) for 30 s loading time was 16. Preconcentration of Cu(II) and potentially interfering metal ions is strongly pH dependent. Examination of Cu(II) sorption in the presence of Pb(II), Cd(II), Zn(II) and Ag(I) showed significant influence of cadmium and zinc ions only and that was for the interferent concentrations above 0.5 mg L −1 (Cu-IIP mass of ca. 35 mg). The interference effect was reduced with the sorbent mass increase. Fe(III) and Mn(II) ions, present in treated tap water in relatively high concentrations, did not interfere. Effective pH adjusting of the loaded solution in on-line mode, when applying diluted Clark-Lubs buffering solution, allowed accurate copper determination in tap water (compared to graphite furnace atomic absorption spectrometry, GFAAS) using standard addition or combination calibration method.
Journal of the Serbian Chemical Society, 2019
A simple, reliable and rapid method for the extraction of ultra-trace copper(II) using nanoporous SBA-15 sorbent modified with a thiocarbohyd-razide ligand, and determination by flame atomic absorption spectrometry is presented. The optimum parameters of the method were obtained as pH of aqueous solution 5, sorbent amount 2 mg, stirring time 20 min and 0.4 M HCl solution as the eluent solvent. This method has a breakthrough volume greater than 1500 mL with a concentration factor of more than 300, linear range 0.8-2500.0 µg L-1 , limit of detection 0.253 µg L-1 and limit of quantification 0.844 µg L-1 for copper(II). The capacity of 2 mg of modified SBA-15was found to be 123.00±0.04 mg g-1. Standard deviations were 3.3, 2.3 and 2.1 % for 1, 2 and 4 μg mL-1 , respectively (n = 5). This method was successfully applied for the determination of copper(II) in different real samples, especially in the food samples.
Instrumentation Science & Technology, 2015
An online flow injection procedure for the preconcentration of copper at μg L -1 levels was developed using a novel chelating resin and flame atomic absorption spectrometry for the analysis of industrial water. Amberlite XAD-2 functionalized with dithizone resin was packed in a minicolumn for flow injection. The pH, sample and eluent flow rates, and eluent concentration were optimized to ensure maximum recovery of Cu(II). The effect of concomittant ions on Cu (II) sorption was also investigated. The limit of detection and enrichment factor for a 180 s preconcentration time were 76 and 0.6 μg L -1 , respectively. The resin offered precision of 1.0 % for seven successive determinations of 100 μg L −1 Cu(II). The resin was used for more than 300 sorption and desorption cycles without appreciable loss of efficiency. The accuracy of the preconcentration procedure was confirmed by fortified recovery studies in industrial water with NIST certified copper nitrate with recovery exceeding 96 %. Validation was performed by the analysis of a standard reference material.
CLEAN - Soil, Air, Water, 2011
An on-line solid phase extraction method for the preconcentration and determination of Cu(II) by flame atomic absorption spectrometry has been described. The procedure is based on the retention of Cu(II) ions at pH 6.0 on a minicolumn packed with Amberlite XAD-1180 resin impregnated with chrome azurol S. After preconcentration, Cu(II) ions adsorbed on the impregnated resin were eluted by 1 mol L À1 HNO 3 solution. Several parameters, such as pH, type of eluent, flow rates of sample and eluent solutions, amount of resin were evaluated. At optimized conditions, for 3.5 min of preconcentration time, the system achieved a detection limit of 1.0 mg L À1 , and a relative standard deviation of 1.2% at 0.2 mg mL À1 copper. An enrichment factor of 56-fold was obtained with respect to the copper determination. The proposed method was successfully validated by the analysis of standard reference material (TMDA 54.4 lake water) and recovery studies. The method was applied to the preconcentration of Cu(II) in natural water samples.
Journal of Chromatography A, 2001
A method based on preconcentration of Cu and Cd from ultra-high-purity water by ion chromatography (IC) and determination by electrothermal atomic absorption spectrometry is described. A small low-capacity ion-exchange concentrator Dionex HPIC-CG5 and mobile phase of 3 mM pyridine-2,6-dicarboxylic acid (PDCA) are used. Water samples are 21 loaded onto the preconcentration column at a flow-rate ranging from 1 to 3.5 ml min . Large sample volumes (up to 200 ml) can be loaded onto the concentrator without losing metal ions. Elution is carried out in the reverse direction of sample loading and the volumes of effluent are as small as 0.150 and 0.200 ml for copper and cadmium, respectively. Under these conditions the preconcentrated ions coelute. The detection limits, based on the Hubaux-Vos method, for Cu using a 21 1300-fold preconcentration in the IC step was found to be 1 pg ml , and was limited due to impurity in PDCA, while the 21 detection limit found for Cd using a 1000-fold preconcentration was 0.02 pg ml . Ultra-high-purity water produced by a Millipore system is successfully analysed by the proposed method and the content of Cu and Cd are found to lie in the range 21 1-10 pg ml .
Mikrochimica Acta, 2007
Cloud point extraction employing the new reagent 6-[2′-(6′-methyl-benzothiazolylazo)]-1,2-dihydroxy-3,5-benzenedisulfonic acid as complexing agent and Triton X-114 as the surfactant is proposed for copper determination. A sample volume of 10 mL was used. Dilution of the surfactant-rich phase with acidified methanol was performed after phase separation, and the copper contents were measured by flame atomic absorption spectrometry. Variables affecting the system were optimized using factorial design and Doehlert matrix. Signals were measured as peak height using an instrument software. Using the experimental conditions defined in the optimization, the method allowed copper determination with a detection limit of 1.5 µg L−1. The calculated enrichment factor is 14. The effects of foreign ions are reported. The accuracy of the procedure was tested by analyzing certified reference material. The method was successfully applied to copper determination in natural and drinking water samples.
Talanta, 2002
A simple, sensitive and low cost, flow injection time-based method was developed for on-line preconcentration and determination of copper, lead and chromium(VI) at sub mg l (1 levels in natural waters and biological samples. At the optimum pH, the on-line formed metal Á/ammonium pyrrolidine dithiocarbamate (APDC) complexes were sorbed on the unloaded commercial polyurethane foam (PUF), and subsequent eluted quantitatively by isobutylmethylketone and determined by flame atomic absorption spectrometry (FAAS). All chemical, and flow injection variables were optimized for the quantitative preconcentration of each metal and a study of interference level of various ions was also carried out. The system offered improved flexibility, low backpressure and applicability to all the studied metals. At a sample frequency of 36 h (1 and a 60 s preconcentration time, the enhancement factor was 170, 131 and 28, the detection limit was 0.2, 1.8 and 2.0 mg l (1 , and the precision, expressed as relative standard deviation (s r), was 2.8 (at 10 mg l (1), 3.4 (at 50 mg l (1) and 3.6% (at 50 mg l (1) for Cu(II), Pb(II) and Cr(VI), respectively. The accuracy of the developed method was sufficient and evaluated by the analysis of certified reference materials and spiked water samples. Finally, the method was applied to the analysis of environmental samples.
Química Nova, 2014
In the present work, a simple and rapid ligand-less, in situ, surfactant-based solid phase extraction for the preconcentration of copper in water samples was developed. In this method, a cationic surfactant (n-dodecyltrimethylammonium bromide) was dissolved in an aqueous sample followed by the addition of an appropriate ion-pairing agent (ClO 4 −). Due to the interaction between the surfactant and ion-pairing agent, solid particles were formed and subsequently used for the adsorption of Cu(OH) 2 and CuI. After centrifugation, the sediment was dissolved in 1.0 mL of 1 mol L −1 HNO 3 in ethanol and aspirated directly into the flame atomic absorption spectrometer. In order to obtain the optimum conditions, several parameters affecting the performance of the LL-ISS-SPE, including the volumes of DTAB, KClO 4 , and KI, pH, and potentially interfering ions, were optimized. It was found that KI and phosphate buffer solution (pH = 9) could extract more than 95% of copper ions. The amount of copper ions in the water samples varied from 3.2 to 4.8 ng mL −1 , with relative standard deviations of 98.5%-103%. The determination of copper in water samples was linear over a concentration range of 0.5-200.0 ng mL −1. The limit of detection (3S b /m) was 0.1 ng mL −1 with an enrichment factor of 38.7. The accuracy of the developed method was verified by the determination of copper in two certified reference materials, producing satisfactory results.
2013
Trace amount of Copper(II) has determined by spectrophotometric technique using 1-(2-pyridylazo)- 2-naphthal (PAN), as a new spectrophotometric reagent which is insoluble in water. PAN reacts in highly acidic solution at pH 2.40 to 2.50 with Cu(II) to give a pink chelate which has an absorption maximum (λmax.) at 550nm. The reaction is instantaneous and absorbance remains stable for over 48hrs. The average molar absorption co- efficient (e) was found to be 2.05×10 4 L mol -1 cm -1 and Sandell sensitivity is 3.23×10 −4 μg cm −2 . Linear calibration graphs were obtained for 0.1-4.0 μgL -1 of Cu(II) and RSD (%) is 1.16. The stoichiometric composition of the chelate is 1:2 (Cu:PAN). Large excess of over 50 cations, anions, and some common complexing agents (e.g. oxalate, phosphate, tartarate, thio-urea) do not interfere in the determination. The method was successfully used in the determination of Cu(II) in Several Standard Reference Materials as well as in some environmental and indust...
Journal of Hazardous Materials, 2011
In this paper, we report a simple and sensitive on-line solid phase extraction system for the preconcentration and determination of Cu(II) by flame atomic absorption spectrometry (FAAS). This method is based upon the on-line retention of copper at pH 5.0 on a minicolumn packed with chloromethylated polystyrene modified by 1-phenyl-1,2-propanedione-2-oxime thiosemicarbazone (PPDOT) as a new solid-phase extraction (SPE) sorbent. The retained Cu(II) ions were eluted with 1.0 M HNO 3 , and transported directly to FAAS for determination. Several chemical and flow variables were studied and optimized for a quantitative preconcentration and determination of copper(II). At the optimized conditions, for preconcentration of 10.0 mL of a sample solution, a linear calibration graph was obtained over the concentration range of 3.00-120.0 g L −1 for Cu(II). The limit of detection (3), limit of quantification (10), and enrichment factor are 0.56 g L −1 , 2.0 g L −1 and 41, respectively. The relative standard deviation (n = 6) at 20 g L −1 of Cu(II) is 2.0%. This method could be applied for determination of trace amounts of Cu(II) in water, soil, and food samples with satisfactory results.