Copper preconcentration

Effective metal ion adsorbent has been prepai ed by the immobilization of propylthioethyleamine ligand onto the surface of silica gel (SN-SiO,).The effectiveness of this material to bind metal ions has been attributed to the complexation chemistry between the ligand and the metal. We are investigating properties of propylthioethyleamine grafted on the surface of silica and possibility of application of the obtained surface for preconcentration of heavy metals such as zinc, lead, cadmium, copper, etc. from water solutions. 

Practical examples of using preconcentrating CMEs include the use of a mixed 2,9-dimcthyl-1.10-phenanthrolinc/carbon-pastc electrode for trace measurements of copper (55), the use of clay-containing carbon pastes for voltammetric measurements of iron (56), the use of polyelectrolyte coatings for the uptake and... 

The concentration of copper in the column eluent was determined by flame atomic absorption spectroscopy of samples which were preconcentrated with ammonium pyrrolidine dithiocarbamate (APDC) and methyl isobutyl ketone. The pH of the acidified sample was adjusted to pH 2.5-3.5 using 400 pi 8 M ammonium acetate (Chelex cleaned). 

Wrembel [485] gives details of a procedure for the determination of mercury in seawater by low-pressure ring-discharge atomic emission spectrometry with electrolytic preconcentration on copper and platinum mesh electrodes. Between 40 5 (open sea) and 50 8 (shore area) xg/l mercury was found in Baltic sea waters. 

Olsen et al. [660] used a simple flow injection system, the FIAstar unit, to inject samples of seawater into a flame atomic absorption instrument, allowing the determination of cadmium, lead, copper, and zinc at the parts per million level at a rate of 180-250 samples per hour. Further, online flow injection analysis preconcentration methods were developed using a microcolumn of Chelex 100 resin, allowing the determination of lead at concentrations as low as 10 pg/1, and of cadmium and zinc at 1 pg/1. The sampling rate was between 30 and 60 samples per hour, and the readout was available within 60-100 seconds after sample injection. The sampling frequency depended on the preconcentration required. 

Fang et al. [661] have described a flow injection system with online ion exchange preconcentration on dual columns for the determination of trace amounts of heavy metal at pg/1 and sub-pg/1 levels by flame atomic absorption spectrometry (Fig. 5.17). The degree of preconcentration ranges from a factor of 50 to 105 for different elements, at a sampling frequency of 60 samples per hour. The detection limits for copper, zinc, lead, and cadmium are 0.07, 0.03, 0.5, and 0.05 pg/1, respectively. Relative standard deviations are 1.2-3.2% at pg/1 levels. The behaviour of the various chelating exchangers used was studied with respect to their preconcentration characteristics, with special emphasis on interferences encountered in the analysis of seawater. 

Brugmann et al. [680] compared three methods for the determination of copper, cadmium, lead, nickel, and zinc in North Sea and northeast Atlantic waters. Two methods consisted of atomic absorption spectroscopy but with preconcentration using either freon or methyl isobutyl ketone, and anodic stripping voltammetry was used for cadmium, copper, and lead only. Inexplicable discrepancies were found in almost all cases. The exceptions were the cadmium results by the two atomic absorption spectrometric methods, and the lead results from the freon with atomic absorption spectrometry and anodic scanning voltammetric methods. 

Berman et al. [735] have shown that if a seawater sample is subjected to 20-fold preconcentration by one of the above techniques, then reliable analysis can be performed by ICP-AES (i.e., concentration of the element in seawater is more than five times the detection limit of the method) for iron, manganese, zinc, copper, and nickel. Lead, cobalt, cadmium, chromium, and arsenic are below the detection limit and cannot be determined reliably by ICP-AES. These latter elements would need at least a hundredfold preconcentration before they could be reliably determined. 

Hiraide et al. [737] developed a multielement preconcentration technique for chromium (III), manganese (II), cobalt, nickel, copper (II), cadmium, and lead in artificial seawater using coprecipitation and flotation with indium hydroxide followed by ICP-AES. The metals are simultaneously coprecipitated with indium hydroxide adjusted to pH 9.5, with sodium hydroxide, ethano-lic solutions of sodium oleate and dodecyl sulfate added, and then floated to... 

Warnken et al. [956] have reported an online preconcentration - ultrasonic nebulisation - ICP-MS method that achieved detection limits of 0.26,0.86,1.5, 10, and 0.44 ng/1 for manganese, nickel, copper, zinc, and lead in seawater. This online preconcentration method compares favourably to the state of-the-art off-line methods. 

Bruland et al. [785] compared voltammetric and AAS (with preconcentration) methods in the determination of copper, lead, and cadmium in seawater. 

Abollino et al. [690] compared cathodic stripping voltammetry and graphite furnace AAS in determination of cadmium, copper, iron, manganese, nickel, and zinc in seawater. The effects of UV irradiation, acidification, and online sample preconcentration were studied. 

Cathodic stripping voltammetry has been used [807] to determine lead, cadmium, copper, zinc, uranium, vanadium, molybdenum, nickel, and cobalt in water, with great sensitivity and specificity, allowing study of metal specia-tion directly in the unaltered sample. The technique used preconcentration of the metal at a higher oxidation state by adsorption of certain surface-active complexes, after which its concentration was determined by reduction. The reaction mechanisms, effect of variation of the adsorption potential, maximal adsorption capacity of the hanging mercury drop electrode, and possible interferences are discussed. 

The application of the Chelex 100 resin separation and preconcentration, with the direct use of the resin itself as the final sample for analysis, is an extremely useful technique. The elements demonstrated to be analytically determinable from high salinity waters are cobalt, chromium, copper, iron, manganese, molybdenum, nickel, scandium, thorium, uranium, vanadium, and zinc. The determination of chromium and vanadium by this technique offers significant advantages over methods requiring aqueous final forms, in view of their poor elution reproducibility. The removal of sodium, chloride, and bromide allows the determination of elements with short and intermediate half-lives without radiochemistry, and greatly reduces the radiation dose received by personnel. This procedure was successfully applied in a study of... 

Mykytiuk et al. [184] have described a stable isotope dilution sparksource mass spectrometric method for the determination of cadmium, zinc, copper, nickel, lead, uranium, and iron in seawater, and have compared results with those obtained by graphite furnace atomic absorption spectrometry and inductively coupled plasma emission spectrometry. These workers found that to achieve the required sensitivity it was necessary to preconcentrate elements in the seawater using Chelex 100 [121] followed by evaporation of the desorbed metal concentrate onto a graphite or silver electrode for isotope dilution mass spectrometry. 

Although ICP-ES is a multielement technique, its inferior detection limits (relative to GFA-AS) necessitate the processing of relatively large volumes of seawater. 250 mL aliquots were found to be useful for the analysis of iron, manganese, zinc, copper, and nickel. Extension of the method to include cadmium, cobalt, chromium, and lead would require improvements in the preconcentration procedure. 

Kingston et al. [32] preconcentrated the eight transition elements cadmium, cobalt, copper, iron, manganese, nickel, lead, and zinc from estuarine and seawater using solvent extraction/chelation and determined them at sub ng/1 levels by GFA-AS. 

Beck et al. [61] used flow injection magnetic sector ICP-MS to determine cadmium, copper, nickel, zinc, and manganese in estuarine waters. The online preconcentration system used Toyopearl A-T Chelate 650 H as chelating resin, and was validated for an alkaline water standard reference material (SLEW-2). 

The copper flow-through CL sensor comprised an anion-exchange column having luminol and cyanide coimmobilized on the resin, while copper was temporarily retained by electrochemical preconcentration on a Au electrode placed in an anodic stripping voltammetric cell [64], Injection of 0.1 mol/L NaOH through the column eluted the reagents, which then reacted with copper, stripped from the electrode to produce a CL signal. The response was linear in the 0.01-10-pg/L... 

Figure 4.14 — (A) Flow injection system for the preconcentration and determination of copper P peristaltic pumps A 0.5 M HNOj B sample q = 2.5 mL/min) C water (jq = 0.5 mL/min) E 1 M NaNOj/O.l M NaAcO, pH 5.4 q = 0.5 mL/min F 1 M NaAcO/2 x 10 M Cu pH 5.0 (9 = 1.0 mL/min) 3-5 valves ISE copper ion-selective electrode W waste I and II 2 and 3 mL of chelating ion exchanger for purification III 100 fil of chelating ion exchanger for metal ion preconcentration. (B) Scheme of the flow system for the determination of halides A 4 M HAcO/1 M NaCl/0.57 ppm F B 1 M NaOH/0.5 M NaCl C, mixing coil (1 m x 0.5 mm ID PTFE tube) Cj stainless-steel tube (5 cm x 0.5 mm ID) ISE ion-selective electrode R recorder. (Reproduced from [128] and [129] with permission of Elsevier Science Publishers and the Royal Society of Chemistry, respectively).

P. Hashemi, S. Bagheri and M. R. Fat hi, Factorial design for optimisation of experimental variables in preconcentration of copper by a chromotropic acid loaded Q-Sepharose adsorbent, Talanta, 68(1), 2005, 72-... 

M. C. Yebra and A. Moreno-Cid, Optimisation of a field flow preconcentration system by experimental design for the determination of copper in sea water by flow-injection-atomic absorption spectrometry, Spectrochim. Acta, Part B, 57(1), 2002, 85-93. 

C. R. T. Tarley, E. C. Figueiredo and G. D. Matos, Thermospray flame furnace-AAS determination of copper after on-line sorbent preconcentration using a system optimised by experimental designs. Anal. Sci., 21(11), 2005, 1337-1342. 

C. Mendiguchia, C. Moreno and M. Garcia-Vargas, Determination of copper in seawater based on a liquid membrane preconcentration system. Anal. Chim. Acta, 460(1), 2002, 35-40. 

Copper, Manganese, Nickel Plants — Flow injection on-line sorption preconcentration in a reactor, electrothermal [84]... 

Komjarova, I. and R. Biust. 2006. Comparison of liquid-liquid extraction, sohd-phase extraction and co-precipitation preconcentration methods for the determination of cadmium, copper, nickel, lead and zinc in seawater. Anal. Chim. Acta 576 221-228. 

Afzali, D., A. Mostafavi, M.A. Taher, and A. Moradian. 2007. Flame atomic absorption spectrometry determination of trace amounts of copper after separation and preconcentration onto TDMBAC-treated analcime pyrocatechol-immobilized. Talanta 71 971-975. 

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