Pre-concentration and determination of Cu (II)

PRE-CONCENTRATION AND DETERMINATION OF Cu (II) SUMMARY Toxic effects of some elements -Found in natural water are very high although their concentrations may be low. That's why correct analysis of these elements or ions is very important for environmental chemistry. These analysis a.re also very important in electronic industries and space technological studies. Recently trace element analysis is very important in materials used for strategical studies. But analysis of trace elements is one of the most difficult and complicated analytical task. In order to obtain reliaDle data, the best way is to seperate and preconcentrate tne analysis of interest from the matrix constituents and to determine them in the isolated state. After concentration, the elements can be determined by sensitive methods. Table. 1 is show General Outline of Trace Analysis. Probably the most well known preconcentration- separation is the solvent extraction by use of chelate forming group reagents such as the well known di thiDcarbomates. With one separation step-in favourable cases-more than 20 elements can be separated and preconcentrated. Prefered solvents are several hydrocarbons, chlorinated hydrocarbons or long-chain ketones, esters etc. In the last few years many organic solvents have become known to be poisonous or even cancerogenic. Therefore many of the laboratories in which solvent extraction for a long time has been used as routine method. Now, it is an abligation to look for alternative technigues in order to substitue the poisonous reagents. One of the powerful techniques which can be used for the replacement of solvent extraction procedures is the VIITable. 1 General Outline of Trace Analysis Factors affecting result o-f analysis Analytical operations Method of determination Homogeneity Storage Tools Atmosfer Reagents > Changes in analyte composition Vessels Reagents Atmosphere Volatility Material to be analysed Sampling Grinding Mixing Surface cleaning i Laboratory Sample i Ashing Dissolved sample - non-destruct i ve / Direct, for solids Direct, for salutes Separation Separation of matrix of traces I Preconcent r at ion Dissolved traces Separation Individual trace constituents Simultaneous determi nation of many cons tituents Determination of individual consti tuents VIIIsorption o-F trace compounds on collector materials, owing special bonding groups or a large specific surface or both o-F them. In literature many investigations can be -Found about the application o-F activated carbon as an adsorbent -For multi element preconcentration. It is shown that numerous examples o-F selective and non-selective separation and enrichment procedures by use o-F activated carbon a,re possible. The most important drawback o-F charcoal, however, is the relatively high level o-F impurities which, -For some important elements, cause remarkable blank values and, in some cases, prevent the application o-F charcoal for a sensitive trace determination in lower concentration ranges. A su-F-Ficient ly good purification of activated carbon which is mostly prepared from different natural products is not passible. To overcome such difficulties, since some years, analysts are looking for adsorbing materials which should have the good properties of activated carbon with higher purity. Subject of this study is based on the application of polymeric reagents as sorbents to the preconcentration: PMAN Cpolymethylacry lonitr i 1 ], PflMA Cpolymethy lmethary- latel and copolymer of the polymers C80 percent methylac- rylonitril + 20 percent methy lmethacry late and 20 percent methylacry lonitr i 1 + 80 percent methy lmethacry late] Air dried resin was suspended in 50 ml of 1 mol/1 HC1, It was filtered after being shaken for 4h in the shaker. It was washed with deionized water until no Cl~ was detectable and was dried in an oven at 80 "C. Particles 841-500 urn in size were used for all studies. Trace amounts of Cu (II) have been enriched from aqueous solutions by exchange of Cu (II) on this polymers. After the Cu (II) adsorbed on the resin is eluted, it is analysed by atomic absorption spectrometry and spectrophotometr ic methods. Cu (II) ion is obtained by elution with hydrochloric acid (1M) eluents. The batch technique was used for determining the exchange capacity of Cu (II) ions. 50 ml of 15 ppm Cu (II) solution (pH 7) was added to 0,1 g of the resin. The mixture was shaken for 2 hours in a glass-stoppered flask. After filtration of the mixture copper was determined in IXthe -Filtrate. Cupper analysis has also been carried out in the eluates obtained by the treatment of the resins with 1 mol I""1 HC1. The resins capacity -For Cupper were found to be 6.10 mg Cu/g PMAN, 6.50 mg Cu/g 4 MN + 1MMA 6.17 mg Cu/g 1MN + 4 MMA, 6.10 mg Cu/g PMMA. E-F-Fect o-F pH for the purpose o-F studying the dependence o-F Cu (II) absorption on pH, 50 ml solutions o-F 10 ppm Cu (II), with pH varying -From 2 to 7 were -Filled into glassstoppered flasks. 0.1 g of resin was added to each solution. All mixtures were shaken for 30 min. At the end of this period, the amount of copper adsorbed on the resins were determined both in the filtrate and eluate. In fact, as it is seen in Table 2, while the adsorption of Cu (II) ions is maxumal at 7 pH. Copper adsorption decreases rapidly with decreasing pH and adsorption above pH 2 is not possible. The exchange capacity was increased at higher pH-values. Table -2 Effect of pH For preconcentration and recovery, 1.5 g resins were filled into glass columns with an internal diameter of 0.5 cm HC1 solution of 0.1 mol I""1 was added, and it was kept for 24 h. Finally the column was thoroughly washed with water until no CI ""was detectable in the eluate. The column prepared in this way was used in the adsorption of Cu (II) ions. Dilute Cu (II) solutions of 0.25 mg.1""1 were passed through the column at a rate of 3.0 ml min"1. Cu (II) adsorbed on the column were eluted by 1 mol l"1 HC1. XThe values obtained are shown in Table. 3 Table. 3. Proconcentration of Cu (II) ions on the resins Cupper analysis were carried out in the eluate. The materials were used to preconcentrate Cu (II) very efficiently -From 0.1 mg.l-1 solutions o-F copper and almost 100 "/. recovery were achieved in every instance. Application to real samples is demonstrated by the successful analysis o-f -fountain water -for copper. The sample containing 2000 ml o-f -fountain water was adjusted to pH 7. The water was passed through the column with a flow rate o-f about 3 ml/min. A-fter passage, the column was washed with water adjusted to pH 7. Then the copper on the resin were eluted with 1 mol l"1 HC1 and the copper were determined by flame atomic absorption spectrometry. XI