a7 _ijc-132207_ (j.ai.percb 1)

International Journal of Chemistry; 2013[02] ISSN 2306-6415

60 www.engineerspress.com

Spectrophotometric Studies and Application of a New Asymmetric Triazene

Ligand for Solid Phase Extraction of Ultratrace Copper and Determination

by Flame Atomic Absorption Spectrometry

Mahmood payehghadr1*, Ahmad Azizi

1, Mohammad Kazem Rofouei

2

1 Department of Chemistry, Payame Noor University, POBOX 19395-3697, Tehran, Iran

2 Faculty of Chemistry, Kharazmi University, Tehran, Iran

Abstract: A new triazene ligand, ([1-(ortoacyl benzene)3-(3,4-dichlorobenzene)triazene]) has been

synthesized and kf value of it is complexes with Hg2+

Ni2+

Cd2+

Pb2+

Cu2+

Ag+ has been determined

spectrophometrically. Because this ligand have good selectivity to copper ion, a simple, reliable and

rapid method for preconcentration and determination of the ultratrace amount of copper using octadecyl

silica membrane disk modified by this ligand, and determination by flame atomic absorption has been

presented. Various parameters including pH of aqueous solution (7-8), flow rates (10 ml. min-1

), the

amount of ligand (6.0 mg) and the type of stripping solvent (0.1M nitric acid) have been optimized. The

breakthrough volume was greater than 500 ml with an enrichment factor of more than 220 and 50ng ml-1

detection limit. The capacity of the membrane disks modified by 6mg of the ligand was found to be 220g

of copper. The effects of various cationic interferences on the percent recovery of copper ion were

studied. The method was successfully applied to the determination of copper ion in different samples.

Keywords: Copper, SPE, Octadecyl, Triazene, FAAS, Spectrophotometry, Formation constant

1. Introduction

Aryl triazenes have been studied for their interesting structural, anticancer, and reactivity properties.

They have been used in medicinal, combinatorial chemistry, in natural synthesis and as organometalic

ligands [1]. Triazenes compounds characterized by having a diazoamino group (-N=N-N



techniques such as liquid-liquid extraction [29], precipitation [30], ion exchange [31], solid phase

extraction [32-33] and membrane filtration [34] improve the analytical detection limit, increase the

sensitivity by several orders of magnitude, enhance the accuracy of the results and facilitate the

calibration. Among these techniques, solid phase extraction is preferred by many researchers and account

of the fast, simple and higher preconcentration factor, rapid phase separation, time and cost saving [35-

36].

Liquidliquid extraction of copper with organic solutions containing different chelating agents such as

dithiocabamates and macrocyclic ligands has attracted considerable attention. However, these classical

extraction methods are usually time-consuming, labor-intensive and require large volumes of high purity

organic solvents. In recent years, different trapped ligands on a variety of solid matrices have been

successfully used for the preconcentration, separation and sensitive determination of trace metal ions [37-

38]. Solid phase extraction (SPE) is an attractive technique that reduces consumption of and exposure to

solvent, disposal costs and extraction time. Solid-phase extraction has advantages over other

preconcentration methods in terms of simplicity, economy, rapidity, reusability of the adsorbent; ease of

automation, higher preconcentration factor, lower consumption of reagents, and more importantly its

environmental friendliness (use of less organic solvents). The most extensively used SPE sorbents are

modified C18 Silica [39], activated carbon [40], alumina [41] and Amberlite XAD resins [42-43]. For

example silica and silica bonded adsorbents offer good advantages in terms of thermal, mechanical and

chemical stability. In addition, they act selectively towards a particular metal ion. In fact, the modified

silica gel surfaces are known to act as a weak cation exchanger via its weak silanol groups, through

immobilization of organic complexing agents, either chemically or physically. These modified surfaces

greatly enhance metal exchange capacity and improve selectivity of these phases to metal ion removal,

separation or preconcentration prior to their determination by x-ray fluorescence or AAS analysis [44-48].

In this work, preconcentration of ultratrace copper (II) in aqueous media using octadecyl silica

membrane disks modified by a recently synthesized triazene (Figure 1) and determination by FAAS have

been reported. Different experimental conditions, e.g. the type and volume of eluting solvent, the effect of

pH, the effect of sample and eluent flow rates and the amount of ligand, on the extraction efficiency and

breakthrough volume, limit of detection and maximum capacity of the disks for Cu2+

ion recovery have

been studied.

Figure 1: The [1-(ortoacyl benzene) 3-(3,4-dichlorobenzene)triazene] ligand



2. Experimental

2.1. Reagents

Extra pure methanol, acetonitrile, nitric acid, hydrochloric acid, acetic acid, sulfuric acid and

perchloric acid (all from Merck) were used as received. The nitrate or chloride salts of the cations (all

from Merck) were of the highest purity available and used without any further purification except for

vacuum drying. Ligand synthesized, purified and dried as it has been described elsewhere [10]. Doubly

distilled deionized water was used throughout. The standard stock solution of copper (II) (1000 ppm) was

prepared by dissolving1.0000 g of copper wire (99.99%) in the least amount of HNO3 and dilution to

1000 ml in a calibrated volumetric flask with water. Working solutions were prepared by appropriate

dilution of the stock solution with water. 0.1 M acetate and phosphate buffer solutions were used for the

pH ranges 4.05.5 and 6.07.5, respectively.

2.2. Apparatus

All UV-Vis Spectra recorded on a computerized double-beam GBC Cintra20 spectrophotometer, using

two matched 10 mm quartz cell. In a typical experiment, 2.0 ml of ligand solution (5.010-5

mol L-1

) in

acetonitrile was placed in the spectrophotometer cell and the absorbance of solution was measured. Then

a known amount of the concentrated solution of metal ions in acetonitrile (1.310-3

mol L-1

) was added in

a stepwise manner using an l0l Hamilton syringe. The absorbance of the solution was measured after

each addition. The metallic ions solution was continually added until the desired metal to ligand mole

ratio was achieved.

The determinations of copper were performed on a PG990 Atomic Absorption Spectrometer under the

recommended conditions. A Metrohm E-603 digital pH meter equipped with a combined glass calomel

electrode was used for the pH adjustments. All of spectrum was made on a UV-visible cintra20

spectrophotometer from GBC Company. The modified C18 extraction disks were used in conjunction

with a standard 47 mm filtration apparatus (Schleicher and Schell, Dassel, Germany) connected to a

vacuum.

2.3. Estimation of formation constants

The formation constant (kf) and the molar absorptivity () of the resulting 1:1 complexes between the

triazene ligand and different metallic ions in acetonitrile at 25C were calculated by fitting the observed

absorbance, Aobs , at various metallic ion / ligand mole ratios to the previously derived equations [49-50]

(Equation 1), which express the Aobs as a function of the free and complexed metal ions and the formation

constant evaluated from a non-linear least-squares program KINFIT [51].



2.4. Sample extraction

Extractions were performed with 47 mm diameter0.5mm thickness Empore membrane disks

containing octadecyl-bonded silica (8 m particles, 60A pore size) from 3M Company. The typical

composition of the disks was 90% w/w octadecyl bonded silica and 10% w/w PTFE fibers. The disks

were used in conjunction with a standard Millipore 47 mm filtration apparatus connected to vacuum.

In order to remove potential interferences and to ensure optimal extraction of the analyte of Interest,

the disk cleaning and conditioning should be done before its use. Thus, after placing the membrane disk

in the filtration apparatus, 10 ml methanol was poured onto the disk and immediately drowns through the

disk by applying a slight vacuum. After all of the solvent has passed through the disk, it was dried by

passing air through it for few minutes. The disk conditioning was then begun by pouring 10 ml methanol

on to the disk. Immediately a low vacuum was applied and the solvent was drowning through the disk

until solvent surface almost reaches the surface of the disk. The disk should not be allowed to soak

without vacuum, and any air should not be allowed to contact with the surface of the disk. Then, a

solution of 5 mg of ligand dissolved in 5 ml acetonitrile was introduced onto the disk and was drawn

slowly through the disk by applying a slow vacuum. The passed solution was collected in a test tube.

Then 2 ml water was added to the test tube and the resulting colloidal solution was again introduced to the

passed through the disk slowly. The filtration step was repeated until the passed solution was completely

clear. Finally, the disk was washed with 25ml water and dried by passing air through it. Thus, the

membrane disk modified by the ligand is now ready for sample extraction.

The general procedure for the extraction of Cu2+

ions on the membrane disk was as follows: The

modified disk was first washed with 0.5 ml methanol followed by washing with 25 ml water. This step

prewets the surface of the disk prior to the extraction of Cu2+ ions from water and ensures a good contact

between the analyte and the ligand. It is important to note that the surface of the disk was not left to

become dry from the time methanol was added until the extraction of Cu2+

ions from water was

completed. The disk was then conditioned with 25 ml of a 0.1 M buffer solution with the same pH as the

sample solution. Then 100 ml of sample solution containing 10 g Cu2+

at optimum pH was passed

through the membrane (flow rate =10 ml min1

). After the extraction, the disk was dried completely by

passing air through it for a few min. The extracted copper was stripped from the membrane disk using

5ml of 0.1 M nitric acid by applying a slight vacuum. The eluted solution was collected in a test tube

and then transferred into a 5 ml calibrated flask. The test tube was washed with another 1 ml portion of

0.1 M HNO3 and added to the flask. Finally, the flask was diluted to the mark with 0.1 M nitric acid. All

working standard solutions of Cu2+

ion were also prepared in 0.1 M nitric acid.

3. Results and discussion

3.1. Spectrophotometric studies

Spectrophotometric studies of complexation reaction between the triazene ligand and metallic ions in

acetonitrile solution revealed that ligand can form stable 1:1 (metallic ion to ligand) complexes with

different metallic ions.



The electronic absorption spectra of triazene ligand (5105

mol L-1

) in the presence and increasing

concentration of Cu2+

(1.310-3

M) ions were recorded (Figure 2) in acetonitrile at 25C. The resulting

complexe of Cu2+ with triazene ligand are distinguished by a little spectral shift toward longer

wavelength. The stoichiometry of the metal complexes was examined by the mole ratio method. Sample

of the resulting plots are shown in Figure 3, at 297 nm for Cu2+

-L and 377 nm for Ag+-L complexes

respectively, and it is evident that 1:1 (metallic ion to ligand) complexes are formed in solution. The

formation constants of the resulting 1:1 metallic ions to the triazene complexes were obtained at 25C by

absorbance measurements of solutions in which varying concentrations of metallic ions were added to

fixed amounts (5.010-5

mol L-1

) of ligand solution. All the resulting absorbance-mole ratio data were

best fitted to Equation 1, which further supports the formation of ML in solution.

0])[1(][ 2 =++ LLfMff CLCKCKLK (1)

For evaluation of the formation constants and molar absorptivity coefficients from absorbance vs.

[M]/[L] mole ratio data, a non-linear least squares curve fitting program KINFIT was used. The resulting

kf of the ligand complexes at 25C are listed in Table 1. The data given in Table 1 revealed that, at 25C,

the stabilities of the complexes varies in the order Hg2+

> Cu2+

> Ag+> Cd

2+> Ni

2+> Pb

2+. Thus, considering

the observed stability, we decided to use ligand as a suitable modifier for the selective concentration and

extraction of Cu2+

ions on the octadecyl silica membrane disks. Some preliminary experiments were

undertaken in order to investigate ligand retention of copper ions by the membrane disk in the presence of

ligand, after the recommended washing, wetting and conditioning procedures were carried out. It was

found that, the membrane disk modified by the triazene ligand is capable to retain Cu2+

ions in the sample

solution quantitatively (the test solution used contained 10 g copper in100 ml water at pH 7.0).

Figure 2: The spectrum of ligand solution (5.0010-5

M) in acetonitrile and increasing concentration of Cu2+

ion

solution (1.3010-3

M).



Figure 3: Mole ratio plots of absorbance as [Cu2+

]/[L] at 297 nm and [Ag+]/[L] at 377 nm.

Table1: Formation constants of different ligand-Mn+

complexes.

Cation Log kf

Hg2+

4.98 0.03

Cu2+

4.47 0.01

Ag+ 3.98 0.02

Cd2+

3.83 0.01

Pb2+

3.52 0.02

Ni2+

2.78 0.04

3.2. Solid phase extraction

3.2.1. Choice of effluent

In order to choose a proper effluent for the retained Cu2+

ions, after the extraction of 10 g copper

from 100 ml water by the modified disks, the copper ions were stripped with different volumes of varying

concentration of different acids and others solvent (Table 2). From the data given in Table2 it is

immediately obvious that, while 5ml of the 0.1 M mineral acids can accomplish the quantitative elution of

copper from the membrane disk, 5ml nitric acid can do the job better. As is also obvious, the lower the

acid concentration used, are suitable for the quantitative elution of the retained copper ions. Thus, 5 ml of

0.1M HNO3 was used as effluent for further studies.



Table 2: Percent recovery of cu2+

from the modified membrane disk using different stripping solution

Stripping solution % Recovery Cu2+

HNO3 (0.1 M) 100

HCl (0.1 M) 64.8

H2SO4 (0.1 M) 100

HNO3 (0.5 M) 100

HCl (0.5 M) 65

H2SO4 (0.5 M) 100

EDTA (0.1 M) 71.1

NH4SCN (0.1 M) 2.2

3.2.2. Effect of pH

The effect of pH on the extraction of copper ions was studied. In order to investigate the effect of pH

on the SPE of copper (II) ion, the membrane disk was modified with 6mg of ligand and the pH of aqueous

samples containing 10g Cu2+

was varied from 4.0 to 8, using appropriate buffer solutions. The resulting

percent recovery versus pH plot is show in Figure 4. As seen, the percent recovery of Cu2+

ion increases

with increasing pH of solution until a pH of about 7 is reached. Quantitative extraction of copper ion

occurs at a pH range 78. The pH values higher than 8 were not tested. Thus, a buffer solution of pH 7.0

was adopted for further studies.

Figure 4: The effect of pH of the sample on extraction recovery of Cu2+

ion.



3.2.3. Effect of ligand amount

As the amount of loaded ligand on the membrane disk increases, the flow rate of solutions through the

modified disk will decrease. Thus, the least amount of ligand necessary for the quantitative extraction of

10 g Cu2+

from a 100 ml aqueous sample at pH 7.0 was studied. The results are shown in Figure 5. As

seen, the extraction of copper is quantitative using above 6 mg of ligand. Hence, subsequent extraction

experiments were carried out with 6mg of the ligand. As seen, the extraction of copper decrease with 8mg

ligand.

Figure 5: Effect of amount of the ligand on extraction recovery of Cu2+

ion.

3.2.4. Effect of flow rate

The effect of flow rates of the sample and stripping solutions from the modified membrane disk on the

retention and recovery of copper (II) was investigated. It was found that, in the range of 5-30ml min1

, the

retention of copper by the membrane disk is affected the sample solution flow rate considerably (Figure

6). On the other hand, quantitative stripping of Cu2+

ions from the disk was achieved in a flow rate range

of 10 ml min1

, using 5 ml of 0.1 M nitric acid. At higher flow rates, quantitative stripping of copper

decreased the recovery.



Figure 6: Effect of flow rate on extraction recovery of Cu2+

ion.

3.2.5. Analytical performance

The maximum capacity of the membrane disk modified by 6 mg ligand was determined by passing

500 ml portions of an aqueous solution containing 300g copper at pH 7.0, followed by the determination

of retained metal ions using FAAS. The maximum capacity of the membrane disk was found to be 220g

of Cu2+

ion on the disk. The breakthrough volume of sample solution was tested by dissolving 10 g of

copper in 100, 250, 500, and 1000 ml water and the recommended procedure was followed under optimal

experimental conditions. In all cases, the extraction by the membrane disk was found to be quantitatively.

Thus, the breakthrough volume for the method should be greater than 500 ml. Consequently, by

considering the final elution volume of 5.0 ml and the breakthrough volume of 500ml, an enrichment

factor of 100 was easily achievable. The limit of detection (LOD) of the proposed method for the

determination of copper (II) was studied under the optimal experimental conditions. The LOD obtained

from CLOD=KbSb/m for a numerical factor Kb=3 is 50 ng ml1.

In order to investigate the selective separation and determination of Cu2+

ion from its binary mixtures

with diverse metal ions, an aliquot of aqueous solution (100 ml) containing 10 g Cu2+and different

amounts (mg) of other cations was taken and the recommended procedure was followed and the results

are summarized in Table 3. The results clearly indicate that 10 g of copper (II) ions in the binary

mixtures are retained almost quantitatively by the modified membrane disk, even in the presence of up to

about 19.66 mg of the diverse ions.

In order to assess the applicability of the method to real samples, it was applied to the separation and

recovery of copper (II) ions from100 ml of three different water and a synthetic sample, and the results

are summarized in Figure 7. As is obvious, the copper (II) ions added can be quantitatively recovered

from the water and synthetic matrices.



Table 3: Separation of copper from binary mixtures. The initial solution contained 10 g copper and different

amount of diverse ion in 100 mL.

Diverse ion Amount taken, mg Recovery of Cu2+

Zn2+

0.44 100

Ni2+

7.05 100

Pb2+

1.87 100

Ba2+

7.04 90.0

Ca2+

2.91 97.3

Mg2+

3.06 77.0

K+ 8.73 89.8

Na+ 19.66 92.5

Hg2+

0.618 50.1

Figure 7: Recovery of 10 g Copper spied to 100 mL of the water sample.

References

1. D. B. Kimball, R. Herges, M. M. Haley, Two Uncommon, Competitive Mechanisms for (2-

Ethynylphenyl)triazene Cyclization: Pseudocoarctate Versus Pericyclic Reactivity, J. Am. Chem.

Soc,. 124 (2002) 1572-1573.

2. N. Chen, M. Barra, I. Lee, N. Chahal, Substituent Effects on the Thermal Cis-to-Trans

Isomerization of 1,3-Diphenyltriazenes in Aqueous Solution, J. Org. Chem., 67 (2002) 2271-

2277.



3. J. Ruiz, J. F. J. Lopez, V. Rodriguez, J. Perez, M. C. Ramirez, D. Arellano, and G. Lopez,

Synthesis and characterization of chelate and bridging triazenide complexes of palladium and

platinum. Stereoselective oxidative addition of chlorine or iodine to [NBu4][Pt(C6F5)2(2-

PhNNNPh)], J. Chem. Soc., Dalton Trans., (2001) 2683-2689 .

4. M. K. Rofouei, M. Shamsipur, M. Payehghadr, Crystal Structure of Triazene-1,3-di(2-

methoxyphenyl), Anal. Sci., 22 (2006) 79 -80.

5. M. Payehghadr, M. K. Rofouei, A. Morsali, M. Shamsipur, Structural and solution studies of a

novel tetranuclear silver(I) cluster of [1,3-di(2-methoxy)benzene]triazene Inorganica Chemical

Acta, 360 (2007) 1792-1798.

6. M. Payehghadr, M. K. Rofouei, A. Naghian, Spectrophotometric Study and Thermodynamics of

1,3-Bis(2-Cyanobenzene) triazene Complexes with Hg2+

and Cd2+

ions, Asian Journal of

Chemistry, 21 (2009) 3841-3850.

7. M. R. Melardi, Z. Roohi, N. Heidaria, M. K. Rofouei, Chlorido[1-(2-ethoxyphenyl)3-(4-

nitrophenyl)triazenido]mercury(II), Acta Crystallographica Section E, Structure Reports, Online

ISSN 1600-5368.

8. M. K. Rofouei, M. Hematyar, V. Ghoulipour, J. A. Gharamaleki, Syntheses, structures, thermal

behavior and solution studies of two types of Hg(II) complexes with [1,3-di(2-

methoxy)benzene]triazene, Inorganica Chim. Acta, 362 (2009) 37773784.

9. M. K. Rofouei, M. Payehghadr, M. Shamsipur, A. Ahmadalinezhad, Solid phase extraction of

ultra traces silver (I) using octadecyl silica membrane disks modified by 1,3-bis(2-cyanobenzene)

triazene (CBT) ligand prior to determination by flame atomic absorption, Journal of Hazardous

Materials,168 (2009) 1184-1187.

10. M. K. Rofouei, A. Sabouri, A. Ahmadalinezhad, H. Ferdowsi, Solid phase extraction of ultra

traces mercury (II) using octadecyl silica membrane disks modified by 1,3-bis(2-

ethoxyphenyl)triazene (EPT) ligand and determination by cold vapor atomic absorption

spectrometry, J. Hazardous Materials, 192 (2011) 1358 1363.

11. T. Hashempur, M. K. Rofouei, A. R. Khorrami, Speciation analysis of mercury contaminants in

water samples by RP-HPLC after solid phase extraction on modified C18 extraction disks with

1,3-bis(2 cyanobenzene)triazene, Microchemical Journal, 89 (2008) 131136.

12. M. K. Rofouei, S. M. Hosseini, H. Khani, S. R. Alangi, Highly selective determination of trace

quantities of Hg (II) in water samples by spectrophotometric and inductively coupled plasma-

optical emission spectrometry methods after cloud-point extraction, Analytical Methods, 4 (2012)

759-765.

13. M. Mohammadi, M. Khodadadian, M. K. Rofouei, A. Beiza, A. R. Jalalvand, Monitoring Trace

Amounts of Silver(I) in Water Samples Using a Potentiometric Sensor Based on 1,3-Bis(2-

ethoxyphenyl)Triazene, Sensor Letters, 8 (2010) 285291.



14. M. Shamsipur, S. Sahari, M. Payehghadr, K. Alizadeh, Flow Injection Potentiometric

Determination of Cd2+

Ions Using a Coated Graphite Plasticized PVC-Membrane Electrode

Based on 1,3-Bis(2-cyanobenzene)triazene, Acta Chim. Slov. 58 (2011) 555562.

15. M. K. Rofouei, M. Mohammadi, M. B. Gholivand, Mercury(II) selective membrane electrode

based on 1,3-bis(2-methoxybenzene)triazene, Materials Science and Engineering C, 29 (2009)

21542159.

16. M. B. Gholivand, M. Mohammadi, M. Khodadadian, M. K. Rofouei, Novel platinum(II)

selective membrane electrode based on 1,3-bis(2-cyanobenzene)triazene, Talanta, 78 (2009) 922

928.

17. J. Ghasemi, M. Shamsipur, Spectrophotometric study of the thermodynamic of intraction of some

metal ions with murexide in binary acetonitrile-dimethylsulfoxide mixture. J. Coord. Chem., 36

(1995) 183-194.

18. S. A. Kulichenco, V. O. Doroschuk, S. O. Lelyushok, The cloud point extraction of copper(II)

with monocarboxylic acids into non-ionic surfactant phase, Talanta, 59 (2003) 767-773.

19. P. Hashemi, S. Bagheri, M.R. Fathi, Factorial design for optimization of experimental variables

in preconcentration of copper by a chromotropic acid loaded Q-Sepharose adsorbent, Talanta, 68

(2005) 72-78.

20. P. Ashtari, K. Wang, X. Yang, S. Huang, Y. Yamini, Novel separation and preconcentration of

trace amounts of copper(II) in water samples based on neocuproine modified magnetic

microparticles, Anal. Chim. Acta, 550 (2005) 18-23.

21. R. J. Cassella, O. I. B. Magalhaes, M. T. Couto, E. L. S. Lima, M. A. F. S. Neves, F. M. B.

Coutinho, Synthesis and application of a functionalized resin for flow injection/F AAS copper

determination in waters, Talanta, 67 (2005) 121-128.

22. O. Acar, Determination of cadmium, copper and lead in soils, sediments and sea water samples

by ETAAS using a Sc + Pd + NH4NO3 chemical modifier, Talanta, 65 (2005) 672-677.

23. J. Y. Cabon, Determination of Cu and Mn in seawater by graphite furnace atomic absorption

spectrometry with the use of hydrofluoric acid as a chemical modifier, Spectrochim. Acta B 57

(2002) 939-950.

24. P. Rumori,V. Cerd`a, Reversed flow injection and sandwich sequential injection methods for the

spectrophotometric determination of copper(II) with cuprizone, Anal . Chim. Acta, 486 (2003)

227-235.

25. J. J. Pinto, C. Moreno, M. Garca-Vergas, A very sensitive flow system for the direct

determination of copper in natural waters based on spectrophotometric detection, Talanta, 64

(2004) 562-565.



26. S. Meseguer-Lioret, P. Campnas-Falco, S. Cardenas, M. Gallego, M. Valcarcel, FI automatic

method for the determination of copper(II) based on coproporphyrin ICu(II)/TCPO/H2O2

chemiluminescence reaction for the screening of waters, Talanta, 64 (2004) 1030-1035.

27. Z. Szigeti, I. Bitter, K. Toth, C. Latkoczy, D.J. Fliegel, D. Gunther, E. Pretsch, A novel polymeric

membrane electrode for the potentiometric analysis of Cu2+

in drinking water, Anal. Chim. Acta,

532 (2005) 129-136.

28. M. P. Hurst, K.W. Bruland, The use of Nafion-coated thin mercury film electrodes for the

determination of the dissolved copper speciation in estuarine water, Anal. Chim. Acta, 546 (2005)

68-78.

29. P. Bermejo-Barrera, A. Moreda-Pineiro, R. Gonzalez-Iglesias, A. Bermejo- Barrera,

Multivariate optimization of solvent extraction with 1,1,1-trifluoroacetylacetonates for the

determination of total and labile Cu and Fe in river surface water by flame atomic absorption

spectrometry, Spectrochim. Acta, B 57 (2002) 1951-1966.

30. M. Soylak, S. Saracoglu, U. Divrikli, L. Elci, Coprecipitation of heavy metals with erbium

hydroxide for their flame atomic absorption spectrometric determinations in environmental

samples, Talanta, 66 (2005) 1098-1102.

31. S. Scaccia, G. Zappa, N. Basili, Ion chromatographic preconcentration of Cu and Cd from ultra-

high-purity water and determination by electrothermal atomic absorption spectrometry, J.

Chromatogr. A, 915 (2001) 167-175.

32. E. Kendzler, A. R. Trker, Atomic absorption spectrophotometric determination of trace copper

in waters, aluminium foil and tea samples after preconcentration with 1-nitroso-2-naphthol-3,6-

disulfonic acid on Ambersorb 572 , Anal. Chim. Acta, 480 (2003) 259-266.

33. V. A. Lemos, P. X. Baliza, Amberlite XAD-2 functionalized with 2-aminothiophenol as a new

sorbent for on-line preconcentration of cadmium and copper, Talanta, 67 (2005) 564-570.

34. U. Divrikli, A. A. Kartal, M. Soylak, L. Elci, Preconcentration of Pb(II), Cr(III), Cu(II), Ni(II)

and Cd(II) ions in environmental samples by membrane filtration prior to their flame atomic

absorption spectrometric determinations, J. Hazard. Mater., 145 (2007) 459-464.

35. M. Ghaedi, K. Niknam, A. Shokrollahi, E. Niknam, H. R. Rajabi, M. Soylak, Flame atomic

absorption spectrometric determination of trace amounts of heavy metal ions after solid phase

extraction using modified sodium dodecyl sulfate coated on alumina, J. Hazard. Mater., 155

(2008) 121-127.

36. M. Payehghadr, N. Sateei, L. A. Saghatforoush, Solid Phase Extraction of Ultra Traces Copper

(II) Using Octadecyl Silica Membrane Disks Modified By A New Schiff Base Ligand Prior to

Determination By Furnace Atomic Absorption, Analytical Chemistry an Indian Journal, l0

(2011).

37. M. K. Rofouei, H. Ferdousi Sh, M. Payehghadr, A. M. Fat'hi, Solid Phase Extraction of Ultra

Traces Copper (II) using Octadecyl Silica Membrane Disks Modified by a New Schiff Base Prior



to Determination by Flame Atomic Absorption, Oriental Journal of Chemistry, 27 (2011) 775-

781.

38. J. O. Roman, A. M. Pieiro, A. B. Barrera, P. B. Barrera, Evaluation of commercial C18

cartridges for trace elements solid phase extraction from seawater followed by inductively

coupled plasma-optical emission spectrometry determination, Anal Chim Acta., 536 (2005) 213-

218.

39. S. L. C. Ferreira, H. M. C. Andrade, H. C. dos Santos, Characterization and determination of the

thermodynamic and kinetic properties of the adsorption of the molybdenum(VI)calmagite

complex onto active carbon, J. Coll. Interf. Sci., 270 (2004) 276-280.

40. G. Absalan, M. A. Mehrdjardi, Separation and preconcentration of silver ion using 2-

mercaptobenzothiazole immobilized on surfactant-coated alumina, Sep. Purif. Technol., 33

(2003) 95-101.

41. L. Elci, A. A. Kartal, M. Soylak, Solid phase extraction method for the determination of iron, lead

and chromium by atomic absorption spectrometry using Amberite XAD-2000 column in various

water samples, J. Hazard. Mater., 153 (2008) 454-461.

42. V. N. Bulut, A. Gundogdu, C. Duran, H. B. Senturk, M. Soylak, L. Elci, M. Tufekci, A multi-

element solid-phase extraction method for trace metals determination in environmental samples

on Amberlite XAD-2000, J. Hazard. Mater., 146 (2007) 155-163.

43. E. M. Soliman, M. E. Mahmoud, S. A. Ahmed, Synthesis, characterization and structure effects

on selectivity properties of silica gel covalently bonded diethylenetriamine mono- and bis-

salicyaldehyde and naphthaldehyde Schiff,s bases towards some heavy metal ions, Talanta, 54

(2001) 243-253.

44. N. Soltanzadeh, A. Morsali, Metalorganic supramolecular assemblies generated from

bismuth(III) bromide and polyimine ligands, Polyhedron, 28 (2009) 703-710.

45. G. Mahmoudi, A. Morsali, Crystal-to-Crystal Transformation from a Weak Hydrogen-Bonded

Two-Dimensional Network Structure to a Two-Dimensional Coordination Polymer on Heating,

Growth Design., 8 (2008) 391-394.

46. E. Melek, M. Tuzen, M. Soylak, Flame atomic absorption spectrometric determination of

cadmium(II) and lead(II) after their solid phase extraction as dibenzyldithiocarbamate chelates on

Dowex Optipore V-493, Anal. Chim. Acta., 578 (2006) 213-219.

47. D. Kara, A. Fisher, S. J. Hill, Determination of trace heavy metals in soil and sediments by

atomic spectrometry following preconcentration with Schiff bases on Amberlite XAD-4, J.

Hazard. Mater., 165 (2009) 1165-1169.

48. J. Ghasemi, M. Shamsipur, Spectrophotometric study of the thermodynamic of intraction of some

metal ions with murexide in binary acetonitrile-dimethylsulfoxide mixture. J. Coord. Chem., 36

(1995)183-194.



49. M. Payehghadr, R. Heidari, Conductometric studies of the thermodynamics complexation of Li

+,

Na+, K

+, Mg

2+ and Ba

2+ ions with 4', 4'' (5'')-Di-tert-butyldibenzo-18-crown-6 ligand in

acetonitrile, ethanol and methanol solutions, J. Incl. Phenom. Macrocycl. Chem., In Press.

50. M. Payehghadr, A. Zamani, A. R. Salehi Sadaghiani, M. Taghdiri, Spectrophotometric and

conductometric studies of the thermodynamics complexation of Zn2+

, Ni2+

, Co2+

, Pb2+

and Cu2+

ions with 1,13-bis(8-quinolyl)-1,4,7,10,13-pentaoxatridecane ligand in acetonitrile solution, J.

Incl. Phenom. Macrocycl. Chem., 62 (2008) 255-261.

51. V. A. Nicely, J. L. Dye, general purpose curve fitting program for class and research use. J.

Chem. Educ., 48 (1971) 443-447.

a7 _ijc-132207_ (j.ai.percb 1)

Documents