Development of Extractive Spectrophotometric Method for the Determination of Copper (II) with Isatin-3-Thiosemicarbazone (HITSC)
Gauri P. Tamhane and V. D. Barhate*
V.E. S. College of Arts, Science and Commerce, Sindhi Society, Chembur, Mumbai - 400071
*Corresponding Author E-mail: vasantbarhate@yahoo.co.in
ABSTRACT:
A simple extractive spectrophotometric method has been developed for the determination of Cu(II) by using Isatin - 3 - Thiosemicarbazone(HITSC) as an analytical reagent .HITSC has been synthesized and characterized by elemental and
spectral analysis. HITSC extracts Cu(II)quantitatively (99.67%) into Nitrobenzene from an aqueous solution of pH range 5.5– 6.5. Nitrobenzene extract shows an intense peak at460 nm (λ max).Beer’s law is obeyed over the Cu (II) concentration range of 1.0 to 5.0µg/ml. The Sandell’s sensitivity and molar absorptivity for Cu-HITSC system is 9.523ngcm-2and 6673.02L mole-1cm-1 respectively. The composition of extracted species is found to be 1:2 (Cu: HITSC) by Job’s Continuous Variation and Mole Ratio Method. Interference by various ions has been studied. The proposed method has been successfully applied for determination of Cu(II) in pharmaceutical sample and Al-alloy.
KEYWORDS: Extractive Spectrophotometry, Copper(II), Isatin - 3 -Thiosemicarbazone (HITSC), pharmaceutical sample, Al-alloy
Copper is technically important metal after iron. It is one of the nine elements essential to mammalian life. It is used in many fields, either as metal or its salts, such as industry, laboratory, medicine, food and beverage. Copper and its salts are highly toxic to lower organisms much more than man. It is however, an essential constituent of certain proteins. In biological system copper counter acts the toxicity of zinc suggesting Cu-Zn antagonism1. Its toxic effect is the main cause of Wilson’s disease2. In plant physiology it is essential as a component of a number of different plant enzymes 3. It is one of the most harmful impurities in semiconductor materials 4. Separation of copper from other elements is important for its recovery from different materials. A rapid and reliable method for determination of trace amount of copper is very useful in the study of its role as ultra pure metal and in biological system. Copper (II) forms chelate complex with many organic reagents, which are bonded through nitrogen, oxygen and sulphur atoms5-9. These complexes are widely used for the separation and spectrophotometric determination of copper. In the present communication, we describe the extractive spectrophotometric determination of Cu (II) by using isatin-3-thiosemicarbazone.
ELICO - SL 159 spectrophotometer with optically matched quartz or glass cells of 1cm path length was used for absorbance measurement. An ELICO - LI 127 pH meter was employed for pH measurements.
Procedure for the preparation of Copper stock solution:
A stock solution of Cu (II) was prepared by dissolving accurately weighed amount of copper sulphate in double distilled water containing sulphuric acid and it was standardized by Diethyl dithiocarbamate method11. Working solutions of Cu (II) were made by diluting the stock solution to an appropriate volume. All other reagents used were of AR grade and all the solutions were prepared in doubly distilled water.
Procedure for preparation of Isatin-3-Thiosemicarbazone (HITSC)10:
A mixture of 2g thiosemicarbazide and 6g sodium acetate was dissolved in 50 ml of water. To this 2gisatin dissolved in 27-30 ml of alcohol was added and the whole mixture stirred for 10-15 min. It was refluxed on a waterbath for 3-4 hours and then cooled in ice when a yellow precipitate was obtained. It was filtered,dried and recrystalised with alcohol(m.p.270 0Cand yield 60.0%).The product was characterized by elemental and spectral analysis. Its solution was prepared in Dimethylformamide (DMF).
Extractive Spectrophotometric Determination of Cu(II):
To an aliquot of aqueous solution containing 10.0 -50.0µg of Cu (II), 4ml of sodium acetate –acetic acid buffer solution of pH 6.0 and 1ml of 0.1% solution of HITSC prepared in DMF were added. The volume of solution was made up to 10 ml with distilled water. The solution equilibrated for 1 minute with 10 ml of nitrobenzene and the phases were allowed to separate. The nitrobenzene extract was collected in a 10 ml measuring flask and made up to mark with nitrobenzene, if necessary. The absorbance of nitrobenzene extract was measured at460 nm against a reagent blank prepared under identical conditions. The measured absorbance was used to compute the amount of Cu (II) present in the sample solution from predetermined calibration curve. To study the effect of other ions, the respective foreign ions were added to aqueous phase before the extraction and adjustment of pH.
Boiling with 10 ml of aquaregia dissolved 0.5 g of pharmaceutical sample. The solution was evaporated to dryness and the residue was dissolved in 10 ml of 1MHClfilter, if required and solution was diluted to 100 ml with doubly distilled water. An aliquot of this solution (1ml) was analyzed for Cu(II) by the procedure as described earlier.
The result shows that the system confirmed to Beer’s law at this wavelength over a Cu(II)concentration range of 1.0 - 5.0 µg/ml[Fig -II]. The molar absorptivity of the extracted complex on the basis of Cu(II) content was calculated to be 6673.02 L mol–1 cm–1. It was found that 1ml of 0.1% solution of HITSC prepared in DMF was sufficient to extract 50 µg of Cu (II). The colour of the nitrobenzene extract was found to be stable at least 12 hrs. at room temperature.
Fig -I
Solution A: Absorbance spectra of HITSC
Solution B: Absorbance spectra of Cu –HITSC Complex
Fig - II Calibration Curve for Cu(II)
Effect of foreign ions:
Cu (II) (30µg) was determined in the presence of various ions. The following ions in the amount indicated, did not interfere in the spectrophotometric determination of Cu(II) (30 µg):10
Effect of foreign ions:
Cu (II) (30µg) was determined in the presence of various ions. The following ions in the amount indicated, did not interfere in the spectrophotometric determination of Cu(II) (30 µg):10 mg each of Co(II), Fe(II),Fe(III), Cd(II), Mn(II),Ba(II),Ni(II),Mg(II),Hg (II), Sr(II),Zn(II),Ca(II), Pb(II),Sn(II), Bi(III), Ti(III), Ce(IV), Zr(IV), Th(IV),MO(VI), W(VI),Li(I),V(V),Ag(I)and 100µg each of Ru(III),Rh(III),Pt(IV) and Pd(II) . 20 mg each of S2O32-, S2O82-, SO42-, SO32- NO2-, NO3-, PO43-, oxalate, chloride, bromide, cyanide, tartarate, thiourea, acetate and citrate .Interference by the Cr (III)was removed by using ammonium acetate as masking agent.
Composition of the Extracted Complex:
The composition of the extracted complex was found to be 1:2 (Cu: HITSC) by Job’s continuous variation [Fig - III] and Mole ratio methods. [Fig - IV
Fig - III Job's Continuous Variation Method
Fig - IV Mole Ratio Methods
Precision, Accuracy, Sensitivity and Applications of Method: The precision and accuracy of the method were tested by analyzing the solution containing a known amount of Cu (II) following the recommended procedure. The average of 10 determination of 40µg of Cu (II) in 10 cm3 solutions was 39.5 µg, which is varied between 41.523 and 37.477 at 95% confidence limit. Standard deviation and Sandell’s sensitivity of the extracted species is found to be ±2.830and 9.523ng.cm-2respectively. The proposed method has been applied for the determination of Cu(II) in pharmaceutical sample and Al-alloy. The results of the analysis of the sample were comparable with those obtained by the standard method11for Cu(II) (Table - I).
Table – I
Samples |
Cu (II) found(mg)/% Present method |
Diethyl dithiocarbamatemethod11 (mg) / % |
|
Supradyn |
3.32 |
3.35 |
|
Al-alloy |
8.02% |
7.98% |
*Average of three determinations
CONCLUSION:
The extractive spectrophotometric determination of Cu (II) was successfully carried out. The reagent HITSC formed complex with copper (II) that was easily extracted into organic phase. The method is simple and reliable. Experimental conditions for maximum extraction was determined and applied for the analysis of Supradyn tablet and Al-alloy to determine the copper content. The results of the analysis of the sample were comparable with those obtained by the standard method11 for Cu (II).
ACKNOWLEDGEMENT:
Authors are thankful to the Principal Dr. (Mrs.) J. K. Phadnis, V.E. S. College of Arts, Science and Commerce, Sindhi Society, Chembur, Mumbai - 71 for providing necessary research facilities.
REFERENCES:
1. Khopkar SM and Chalmers RA .Solvent extraction of Metals. Van Nostrad Reinhold Co. London. 1970.
2. Feig F. Chemistry of specific, selective and sensitive Reactions. Oesper RE .English Ed. New York.1949.
3. Mirzaeva KA, Akhmedove MS and Akhmedov SA. Extraction and spectrophotometric determination of dimedrol and papavarine in pharmaceutical dosage forms .J. Analytical Chem. 59(1); 2004: 215- 218.
4. Singh RB, Garg B Sand Singh RP. Talanta. 26; 1979: 525-526.
5. Shah SS and Parmar RG. Der Pharma Chem. 3(1); 2011: 318-321.
6. Nath R, Nantial SC and Singh H. Labdev Part-A. 12A (2); 1974: 53 -58.
7. Garole DJ and Sawant AD. J. Scientific and Ind. Res. 64(1); 2005: 581-584.
8. Shar GA and. Soomro GA. The Nucleus.41 (1-4); 2004:77-82.
9. Ramachandraih C, Kumar Rajesh and Reddy JK .J. EnviromentalManagement.88 (4); 2008: 729-736
10. A.I. Vogel, Practical Organic Chemistry, 5th Edition Lozyman Group Ltd., London (1989).
11. Scott. WW, Standard Methods of Chemical Analysis. Von Nostrand Company Inc. 1932: 182.
Received on 24.02.2012 Modified on 05.03.2012
Accepted on 16.03.2012 © AJRC All right reserved
Asian J. Research Chem. 5(3): March 2012; Page 351-354