With Solvent Extraction Method, and via new Organic Reagent 2-(Benzo thiazolyl azo)-4,5-Diphenyl Imidazole for Spectrophotometric Determination of Copper (II) in different Samples

: The new organic reagent 2-[Benzo thiazolyl azo]-4,5-diphenyl imidazole was prepared and used as complexing agent for separation and spectrophotometric determination of Cu 2+ ion in some samples include plants, soil, water and human blood serum. Initially determined all factors effect on extraction method and the results show optimum pH was (pH ex =9), optimum concentration was 40μg/5mLCu 2+ and optimum shaking time was (15min.), as well stoichiometry study appears the complex structure was 1:1 Cu 2+ : BTADPI. Interferences effect of cations were studied. Synergism effect shows MIBK gave increasing in distribution ratio (D). Organic solvent effect appears there is no any linear relation between dielectric constant for organic solvent used and distribution ration (D). Thermodynamically found the reaction was Endothermic reaction, with ΔH ex = 0.0131 KJ.mole -1 ,ΔG ex =- 54.20 KJ.mole -1 ,ΔS ex = 167.84 J.mole -1 .Beer’s law was obeyed over the concentration 1-30μg/5mL, and ε=922.90 Lmol -1 .cm -1 ,with detection limit 1.7 × 10 -5 and Sandell’s sensitivity 6.8 × 10 -7 gcm -2 .


Introduction:
Separation and determination of metal ions have been one of the most important topics of analytical Chemistry.
Developing highly functional Chelating agents has been a great concern of many analytical Chemists.
Investigations into developing new type of Chelating agents have produced many functional results having high sensitivity.New chelating resin was prepared by coupling Amberlite XAD-4 with 1amino-2-naphthole through an azo spacer.The resulting sorbent has been characterized by FT-IR, element alanalysis and thermo gravimetric analysis and studied for preconcentrating of Cu (II) using FAAS for metal monitoring, and the optimum pH value for sorption of the Cu 2+ was 6.5 [1].An extraction and sensitive differential pulse anodic stripping voltammetric method at hanging mercury drop electrode is described for the determination of Zn, Cu, Pb (μg g -1 ) and Cd (ng g -1 ) metal ions in water and 0.1MHCl extracts for Kakade, anise, Cumin, Caraway and black pepper [2].The significant spectral overlap (Di)0.5 = 0.5667 which is about 75.3% overlapping of the UV/Vis, absorption spectra of Fe (II) and Cu(II) complexes necessitates chemometric assisted methods for simultaneous analysis of these ions in the pharmaceutical mixture.These metal ions have been analyzed simultaneously by UV/Vis.spectrophotometric method where 8hydroxyquinoline was used as a chromogenic reagent.The methods were successfully applied for analyzing synthetic mixtures and commercial pharmaceutical preparation [3].The synergistic extraction of Cu (II) with N-phenyl benzo hydroximic acid (PBHA) and tri-n-octyl phosphinoxide or tributyl phosphate was investigated in CHCl 3 .The effect found in presence of natural ligand is due to formation of the adduct Cu(PBHA) 2 S in CHCl 3 .The synergic coefficients were determined which have higher value in presence of TOPO than TBP, since TOPO has the higher basicity than TBP [4].A solid phase extraction method was developed for pre-concentration and spectrophotometric determination of copper in water samples by using lead 4-benzyl piperidine dithiocarbamate complex (Pb(4-BPDC) 2 ), Cu in large volume liquid phase quantitively replaces lead on colorless (Pb(4-BPDC) 2 ) complex and naphthalene solid phase mixture forming Cu(4-BPDC) 2 λ max =437nm, linearity is 0.4-10gmL -1 of Cu, ε=8.197×10 3 L.mol - 1 .cm - [5].Spectrophotometric determination of Cu (II) based on the reaction at pH4-9 between the synthesized acetophenone-p-chloro phenyl thiosemicarbazone (A-p-CIPI) and Cu(II) forming a green complex Cu +2 :A-p-CIPI (1:2) that floats quantitively with oleic acid surfactant, λ max =600nm in both aqueous and surfactant layers, ε=5.5×10 3 and 1.3×10 4 Lmol -1 cm -1 inaqueous and surfactant layers, Beer's law is obeyed over the range 0.25-6.35mgL - with DL=0.021mgL -1 for a standard aqueous solution of Cu (II) with a concentration of 3.82 mgL -1 , Sandell's sensitivity was 0.244μg cm 2-[6].Spectrophotometric method has been developed for the determination of Cu(II) by using 2,3,4trihydroxyacetophenonephenylhydrazo ne (THAPPH) as an analytical reagent.The metal ion has formed 1:2 (M:L) bluish green coloured complex with THAPPH in HCl-KCl buffer of pH 2.5.Beer's law was obeyed in the range 0.04-0.64μg/ml of Cu(II) at λ max =385 nm.
ε=1.0053×10 5 L.mol -1 cm -1 and Sandell's sensitivity (0.0006265 μgcm - 2 ), SD (0.0024),RSD (0.47%), confidence limit (±0.0017), and standard error (0.0008).The interfering effect of various cations and anions has been also studied.The reliability of the method was assured by analyzing the standard alloys, Brass, Bronze, and Phosphor-Bronze.This method was successfully employed for the determination of Cu(II) in food and medicinal leafy samples and inter compared the experimental values using AAS and statistically evaluated using F-test.[7].

Chemicals and reagents:
All Chemicals used in this study were analytical reagents grade (Fluka, Merck & BDH).The stock standard Copper(II) solution 1mg/mL was prepared by dissolving 0.3928gm of CuSO 4 .5H 2 Oin distilled water contain 1mL of concentration H 2 SO 4 and diluting to 100mL.1×10 - M Stock dithiazone solution prepared by dissolving (0.0256gm) of dithiazone in 10mL of CCl 4 .The stock organic reagent Solution 1×10 -2 M was prepared by dissolving 0.0381gm of BTADPI in 10mL Chloroform other working solutions prepared by appropriate dilution with suitable solvent.

Preparation of organic reagent:
Preparation of 2-(Benzo thiazolyl azo)-4,5-diphenyl imidazole (BTADPI)consisted of processing in three steps from commercially available material.As below: General procedure: Extraction experiment was carried out for Cu +2 ions in aqueous solutions by 5mL of 1×10 -4 M organic reagent BTADPI dissolved chloroform shaking the two layers for fixed time separate organic layer from aqueous layer and determine remainder quantity of Cu +2 in aqueous phase spectrophotometrically by dithiazone method [8].Also determine Cu +2 ions transferred to the organic phase to share in complex formation, at later calculate distribution ratio (D).On the other hand, determined λ max for complex in organic solvent for spectrophotometric determination of Cu +2 ions in different samples, environmental and vital samples digested by dry digestion method [9], 5mL digested solution shaked with 5mL of 1×10 -4 M organic reagent dissolved in chloroform for (15min) at pH ex =9, and add 2mL of 1×10 -2 M sodium fluoride, after separated the two layers taken the absorbance of organic phase λ max =494nm against organic reagent as blank.

Results and Discussion: Spectrophotometric Studies:
UV.-Vis spectrum as in Figures (1,2) and Table (1) shows λ max =332nm for organic reagent and λ max =494nm for its complex with Cu 2+ these results show complex formation between organic reagent and Cu 2+ ions [10,11].While IR-spectrum as in Figures (3,4) and Table(1) the spectrum of Cu 2+ complex with organic reagent show shift for absorbance peaks ( -N-H, C-H, C=N, -N=N-, C-S

Effect of foreign ions:
The effect of some foreign ions, which often accompany copper (II), was examined by carry out the determination of 40µg/5mL of Cu 2+ in presence of a number of other ions.The results in Table ( 5), indicate the foreign ions giving high interfere with the determination of copper (II).Then must be used masking agents when determination copper ion in foundation of these foreign ions.16) was constructed with ten standard solutions containing 1-30µg/5mL of copper (II), the formula for the best line of calibration y = 0.0031x + 0.00019, and the correlation coefficient was obtained with the method of least squares R² = 0.999, the molar absorptivity of the complex determined from the linear portion of Beer's law plot ε=922.90L.mol - .cm - , and Sandell's sensitivity 6.8×10 -7 gcm -2 .

Fig
Fig. (16): Calibration curve of Cu 2+ with BTADPI Application: Soil samples The soil contains copper at the range 10-200ppm and this different return to nature of soil according to WHO measurements[14,15]Spectrophotometr ic determination of Cu 2+ ions in different soil samples by BTADPI as the results in Table (8) and Figure(17).

Fig.( 17
Fig.(17): The quantity of Copper(II) in soil *ppm: copper quantity determined by this Spectrophotometric determination method **AAs: copper quantity determined by Atomic absorption method

Fig
Fig.(19): The quantity of Copper(II)in water

Fig
Fig.(20): The quantity of Copper(II) in human blood serum

18): The quantity of Copper(II) in plant Water samples
Spectrophotometric determination of Cu 2+ ions in different water samples by BTADPI as the results in Table (10) and Figure(19).The range of copper in water according to WHO measurements is 2ppm[14,15].