Atomic Spectrophotometric Determination of Iron, Cobalt and Copper after Separation and Preconcentration by Adsorption of Their Ternary Complexes with Nitroso-R Salt and Cetyltrimethylammonium Bromide onto Benzophenone

Abstract

A liquid-liquid extraction has widely been used as one of the techniques by which trace metal ions in aqueous solution could be separated and concentrated. 1 However, some metal complexes that slightly dissolve in liquid solvent and are stable in solution at high temperature could be concentrated and extracted more effectively, rapidly and quantitatively by solid-liquid separation using microcrystalline naphthalene or benzophenone. 2,3 But this method suffers from the volatility of the fused organic material caused by a high temperature of 70 -90˚C. In order to overcome this difficulty, a modified technique based on the adsorption of metal complex at room temperature onto microcrystalline organic substance was used. 4,5 UV-Vis spectrophotometry has usually been used to determine the analytes after solid-liquid separation. [4][5][6][7][8] In the case of using UV-Vis spectrophotometry, however, the spectral interference due to overlapping of the maximum absorption wavelengths may occur when various metal ions are contained in a real sample. So, the atomic absorption spectrometry that had only slight spectral interference was used in this study.The determination of Fe 3+ , Co 2+ or Cu 2+ has been performed after solid-liquid separation. [8][9][10][11][12] Solid-liquid separation has been usually applicable to binary complexes, but in case of ternary complexes, only some metal ions could be separated. Such a ternary complex was not well formed and was unstable at high temperature. 13One example where such separation was applicable to a ternary complex was Fe 2+ -dipyridyltetraphenylborate. 14 Also, the metal-nitroso-R salt anionic complexes which metal ions were Fe 3+ , Co 2+ and Cu 2+ , were retained on tetradecyldimethylbenzylammonium iodide supported on naphthalene in column. 15 In this study, the determinations of Fe 3+ , Co 2+ and Cu 2+ were performed after separation and adsorption of their ternary complexes with nitroso-R salt and CTAB onto benzophenone at 30˚C. The ternary complexes of Fe 3+ , Co 2+ and Cu 2+ could simultaneously be preconcentrated with excellent efficiency at about room temperature by this technique. And this method was more sensitive, more rapid and had less spectral interference than with UV-Vis spectrophotometry. Experimental InstrumentationA GBC Model 903 flame atomic absorption spectrophotometer was used to determine Fe 3+ , Co 2+ and Cu 2+ . The measuring conditions were as follows: 10 cm 1-slot burner; air(16 l/min)-acetylene(1.5 l/min) flame; 0.5 nm spectral bandwidth; 12 mm burner height. The wavelengths and the lamp currents of Fe 3+ , Co 2+ and Cu 2+ were 248.3 nm, 240.7 nm and 324.8 nm, and 7.0 mA, 6.0 mA and 4.0 mA, respectively.To adjust pHs, a Bantax Model 300A digital pH meter with a combined glass and calomel electrode was used. Reagents and solutionsChemicals such as iron(III) nitrate nonahydrate (Aldrich Co.), cobalt(II) nitrate heptahydrate (Aldrich Co.), copper(II) nitrate hexahydrate (Aldrich Co.), nitroso-R salt (BDH Chemical Co.), benzophenone (Yakuri Co.) and cetylt...

Selective back-extraction and preconcentration of zinc(II) from metal-1,3,5-triketone extracts prior to its determination by flame atomic absorption spectrometry

“…It has been widely used as one of the techniques by which trace metal ions in aqueous solution could be separated and preconcentrated [13]. Solvent extraction provides a convenient way to preconcentrate and it has been widely used for the separation of various metal ions.…”

Selective Separation and Preconcentration of Fe(III) and Zn(II) Ions by Solvent Extraction Using a New Triketone Reagent

“…Solvent extraction is a very effective separation technique 12, finding numerous applications in modern analytical chemistry 13, 14. It has been widely used as one of the techniques by which trace metal ions in aqueous solution could be separated and concentrated 15. Solvent extraction provides a convenient way to the problem and it has been widely used for the separation of various metal ions.…”

Second and First-Derivative Spectrophotometry for Efficient Simultaneous and Individual Determination of Palladium and Cobalt Using 1-(2-Pyridylazo)-2-naphthol in Sodium Dodecylsulfate Micellar Media

“…Copper and cobalt are metals that appear together in many real samples. Several techniques such as X-ray fluorescence 1 , atomic fluorescence spectrometry 2 , polarography 3,4 , high performance liquid chromatography 5−7 , atomic absorption spectrometry 8,9 , chemometrics-based methods 10−13 , spectrophotometric methods in micellar media 14 , flow system with electrochemical detection 15 , time resolved chemiluminescence 16 , and deriva-tive spectrophotometry 17 have been applied for simultaneous determination of these ions in different samples. Among the most widely used analytical methods are those based on UV-visible spectrophotometry techniques, due to both experimental rapidity and simplicity and the wide application.…”