Application of cotton as a solid phase extraction sorbent for on-line preconcentration of copper in water samples prior to inductively coupled plasma optical emission spectrometry determination

Journal of Hazardous Materials 166 (2009) 1383–1388

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Application of cotton as a solid phase extraction sorbent for on-line preconcentration of copper in water samples prior to inductively coupled plasma optical emission spectrometry determination Mohammad Faraji a , Yadollah Yamini a,∗ , Shahab Shariati b a b

Department of Chemistry, Tarbiat Modares University, P.O. Box 14115-175, Tehran, Iran Department of Chemistry, Faculty of Sciences, Islamic Azad University, Rasht Branch, Rasht, Iran

a r t i c l e

i n f o

Article history: Received 21 October 2008 Received in revised form 10 December 2008 Accepted 11 December 2008 Available online 24 December 2008 Keywords: Copper On-line solid phase extraction ICP-OES CAS Water samples

a b s t r a c t Copper, as a heavy metal, is toxic for many biological systems. Thus, the determination of trace amounts of copper in environmental samples is of great importance. In the present work, a new method was developed for the determination of trace amounts of copper in water samples. The method is based on the formation of ternary Cu(II)–CAS–CTAB ion-pair and adsorption of it into a mini-column packed with cotton prior applying inductively coupled plasma optical emission spectrometry (ICP-OES). The experimental parameters that affected the extraction efficiency of the method such as pH, flow rate and volume of the sample solution, concentration of chromazurol S (CAS) and cethyltrimethylammonium bromide (CTAB) as well as type and concentration of eluent were investigated and optimized. The ion-pair (Cu(II)–CAS–CTAB) was quantitatively retained on the cotton under the optimum conditions, then eluted completely using a solution of 25% (v/v) 1-propanol in 0.5 mol L−1 HNO3 and directly introduced into the nebulizer of the ICP-OES. The detection limit (DL) of the method for copper was 40 ng L−1 (Vsample = 100 mL) and the relative standard deviation (R.S.D.) for the determination of copper at 10 ␮g L−1 level was found to be 1.3%. The method was successfully applied to determine the trace amounts of copper in tap water, deep well water, seawater and two different mineral waters, and suitable recoveries were obtained (92–106%). © 2008 Elsevier B.V. All rights reserved.

1. Introduction Copper is a heavy metal extensively examined in environmental, industrial and biological applications. Copper is vital and toxic for many biological systems [1,2], so that its determination in water samples is warranted by the narrow window of concentration between essentiality and toxicity [3,4]. On the other hand, copper is an important element in geochemistry. It can be easily released from silicates, sulfites and oxides after some physical and chemical weathering and then transferred by water into soil and sediments [5]. Thus, the determination of trace amounts of copper in different matrices is of great importance. Despite the sensitivity and selectivity of analytical techniques such as flame atomic absorption spectrometry (FAAS) and inductively coupled plasma optical emission spectrometry (ICP-OES), there is a great necessity for preconcentration of copper prior to its determination, basically due to its low concentration or the effects of matrix in aqueous samples. Preconcentration pro-

∗ Corresponding author. Fax: +98 21 88006544. E-mail address: [email protected] (Y. Yamini). 0304-3894/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.jhazmat.2008.12.063

cedures such as liquid–liquid extraction [6], ion-exchange [7], cloud point extraction [8-10], coprecipitation [6], adsorptive stripping voltametric [11] or solid phase extraction [9] have been applied to extract copper ions from aqueous samples. Solid phase extraction (SPE) is an attractive method that reduces consumption of and exposure to solvent, disposal costs and extraction time [12]. The nature and the properties of the sorbent materials are of prime importance for effective retention of materials in SPE [13]. Ion-exchange resins, Chelex-100 and resin 122 [7]; octadecyl bonded silica gel, C18 [14–16]; modified silica gel [17,18]; polystyrene-divinilbenzene polymer (PS-DVB), Amberlite XAD-2 [19], XAD-4 [20], XAD-2010 [21], PS-DVB functionalized [22]; coated alumina [23]; biopolymer chitosan [24]; polyurethane foam, PUF [25]; polytetrafluoroethylene polymer, PTFE as turnings [26]; polychlorotrifluoroethylene, PCTFE [27]; oxidized multi-walled carbon nanotubes [28,29]; activated carbon [30,31] and doubleimprinted polymer [32] have been used as SPE sorbents to extract copper ions from different water samples. Choi et al. demonstrated that cotton, milkweed and kenaf have 1.5–3 times better sorption properties than polypropylene fibers [33,34]. Because of their excellent oil sorption properties and high biodegradability, wool-based non-woven materials [35] and

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hydrophobic cotton fibers [36] have been adopted to remove oil from water. Recently, cotton column has been applied to selective retaining of synthetic colorants [37] and preconcentration enrichment of polycyclic aromatic hydrocarbons (PAHs) [38]. To the best of our knowledge, cotton fibers have not been employed previously for the extraction and preconcentration of hydrophobic ion-pair of copper with chromazurol S (Cu–CAS) and cationic surfactant of cethyltrimethylammonium bromide (CTAB). In the present study, feasibility of cotton (as a column packing material) was investigated for on-line preconcentration followed by ICP-OES determination of the trace amounts of copper. 2. Experimental Fig. 1. Chemical structure of the CAS.

2.1. Apparatus A simultaneous ICP-OES (Varian Vista-Pro, Springvale, Australia) coupled to a V-groove nebulizer and equipped with a charge coupled device (CCD) was applied for determination of the trace amounts of copper. The operation conditions and the wavelength of the analytical line are summarized in Table 1. A two-channel peristaltic pump model Ultra Voltametry (Farayand Gostar Company, Tehran, Iran) was applied to pump the sample solution through a home-made polyethylene mini-column. The mini-column (25 mm length × 4 mm i.d.) packed with cotton was used in the manifold for extraction/preconcentration process. The pH of the solutions was adjusted and measured by a WTW pH meter (Inolab, Germany) supplied with a combined electrode. A six-way two-position injection valve (Tehran University, Iran) was applied in the preconcentration/elution process. 2.2. Reagent All of the reagents used were of analytical grade. Cu(NO3 )2 ·3H2 O, chromazurol S (CAS), CTAB, ammonium acetate and KI were purchased from Merck Company (Darmstadt, Germany). The stock solution of copper (1000 mg L−1 ) was prepared by dissolving an appropriate amount of Cu(NO3 )2 ·3H2 O in double distilled water. Working solutions were prepared by appropriate dilution of the stock solution with buffer solution. Doubly distilled water was used throughout the work. Acetate buffer solution (0.01 mol L−1 ) was prepared by dissolving sufficient amount of ammonium acetate in water and adjusting the pH with 0.5 mol L−1 nitric acid or 0.5 mol L−1 sodium hydroxide solutions. Stock solutions of CTAB (0.1%, w/v) and 0.15 mol L−1 KI were prepared in double distilled water. In the former case, a stock solution of CAS with a concentration of 0.01 mol L−1 was prepared in distilled water. The chemical structure of CAS is shown in Fig. 1.

packed into the column and blocked by two polypropylene filters at the ends. The column was then connected to the injection valve with PTFE tubing to form preconcentration system. The stability and potential regeneration of the column were investigated. The column can be reused after being regenerated first with 2 mL of methanol and then with 15 mL of distilled water. The column was stable up to 30 adsorption–elution cycles without an obvious decrease in the recovery of copper ions. 2.4. Preconcentration procedure A schematic diagram of the extraction apparatus is shown in Fig. 2. Twenty-five millilitres of the sample solution containing 50 ␮g L−1 of copper and buffered at pH 4.6 was transferred into a 100 mL beaker. After successive addition of 200 ␮L of the 0.02 mol L−1 CAS and 0.6 mL of the 0.1% (w/v) CTAB solutions, the obtained solution was stirred to form ion-pair (Cu–CAS–CTAB). After addition of 2 mL of the 0.15 mol L−1 KI solution, as phase separation reagent, the injection valve (V) was located at “load position” and pump P1 (peristaltic pump) was activated. Then the mixture solution was passed through the mini-column at the flow rate of 6.5 mL min−1 . After completion of loading of the sample solution, the valve, V, was turned to the injection position and the retained ion-pair was eluted using a 0.2 mL of solution of 25% (v/v) 1-propanol in 0.5 mol L−1 HNO3 at the flow rate of 1.2 mL min−1 using ICP peristaltic pump (P2 ). The eluent was then transferred directly into the nebulizer of the ICP-OES. For minimum dispersion, the eluent was passed through the mini-column in reverse direction than that of the sample solution. The peak height of the signal was proportional to copper concentration in the sample, which was used in all of the quantitative measurements. The recorded peak was sharp (width ∼10 s) and the baseline was stable.

2.3. Column preparation 2.5. Sample preparation The preconcentration column was made from a polyethylene syringe tube with an effective length of 25 mm and inner diameter of 4 mm. 150 mg of natural cotton (Kave Company, Iran) was firmly Table 1 ICP-OES operating conditions and analytical line for copper. Plasma gas

Argon

Plasma gas flow rate Auxiliary gas flow rate Frequency of RF generator RF generator power Observation height Nebulizer pressure Wavelength

15 L min−1 1.5 L min−1 40 MHz 1.55 kW 6 mm 130 kPa 324.754 nm

Tap water sample was collected from our laboratory (Tarbiat Modares University, Tehran, Iran) and well water sample was collected from a deep well water in Tarbiat Modares University. The natural mineral waters were collected from Cheshme Ala (Damavand, Tehran) and Cheshme Ghale Dokhtar (Damavand, Tehran). The seawater sample was collected from the Caspian Sea (Noor, Iran). The samples were collected in cleaned polyethylene bottles and only the seawater was filtered through a 0.45 ␮m pore size membrane filters immediately after sampling. The sample’s pH were adjusted to 4.6 using 0.5 mol L−1 nitric acid or 0.5 mol L−1 sodium hydroxide solutions. Finally the proposed method, was applied to extraction of copper ions from the water samples.

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Fig. 2. Schematic diagram of the extraction set up: S, stirrer; M, mixture solution [copper + CAS + CTAB + KI]; E, eluent; W, waste; P1 and P2 , peristaltic pumps; C, mini-column and V, six-port two-position injection valve ((a) load position; (b) injection position).

3. Results and discussion 3.1. Selection of elution reagent and its flow rate Organic solvent like ethanol, methanol and MIBK have been extensively used as effective eluents in on-line solid phase extraction preconcentration systems. In this work, based on our previous work [8], the solutions with different concentrations of nitric acid in 1-propanol were used as eluent. On the basis of the obtained experimental results, the solution of 25% (v/v) 1-propanol in 0.5 mol L−1 HNO3 was chosen as the eluent. The effect of the eluent’s flow rate on ICP-OES signal was studied within the range of 0.8–2.5 mL min−1 . Maximum intensity was obtained at the flow rate of 1.2 mL min−1 . Above that flow rate, the emission intensity of copper decreased mainly due to decreasing of the nebulization efficiency or incomplete elution of the retained ions. Thus, the flow rate of 1.2 mL min−1 was applied in further experiments. 3.2. Effect of the pH Among the chemical variables, pH was the most critical parameter for effective formation and retention of the ternary ion pairs Cu(II)–CAS–CTAB on the cotton. In order to evaluate the effect of pH on the extraction efficiency, the pH of the sample solutions containing 50 ␮g L−1 of copper ions was adjusted in the range of 2.0–7.0 and the recommended procedure was applied. According to obtained results, the maximum intensity was obtained at pH 4.6. At lower pHs (<4.0), a competition occurred between protons and the copper ions for occupying the ligand active sites, while at higher pHs >5.5, the effective charge of CTAB (N-base) decreased. Thus, the pH of the sample solutions was adjusted at 4.6 on the subsequent works.

ing on the concentrations of the components, ternary ion pairs (Cu(II)–CAS–CTAB) with stoichiometries of 1:1:1, 2:1:1 and 1:2:2 were formed. In all of these cases, anionic Cu(II)–CAS complexes were formed [41], to which the CTAB cation is bounded probably from the SO3 − group. Also, the UV–Vis spectrum of the complexes in the presence and absence of CTAB have already been reported [41]. The effect of CAS concentration on the extraction efficiency was studied in the range of 0.0–7.5 × 10−3 mol L−1 . The emission intensities increased by increasing of CAS concentration up to 5.0 × 10−3 mol L−1 , while at higher concentrations, the intensities were decreased. Therefore, a 5.0 × 10−3 mol L−1 solution of CAS was selected for further experiments. 3.4. Effect of CTAB concentration The effect of CTAB concentration on the extraction efficiency was investigated in the range of 0.0–1.2 × 10−2 % and the results are shown in Fig. 3. The presence of surfactant favors the formation of hydrophobic complexes [41]. The emission intensities increased by increasing of CTAB concentration up to 2.4 × 10−3 % (w/v) because of the formation of hydrophobic

3.3. Effect of CAS concentration The use of potentiometric and spectrometric methods have been reported in a study of the complex formation between copper(II) ions and different ligands such as CAS [39]. At the pH range of 5–7, two complexes with the composition of Cu(H2 O)2 HCAS and (Cu(H2 O)2 )2 CAS were detected and the stability constants were calculated as log K = 4.02 ± 0.05 and log K = 13.7 ± 0.1, respectively (at 25 ◦ C and the ionic strength of 0.1 M (KCl)) [40]. Depend-

Fig. 3. Effect of CTAB concentration on the extraction of 50 ␮g L−1 of Cu(II) ions from 25 mL of the sample solution. Conditions: CCAS = 5 × 10−3 mol L−1 , sample pH 4.6, CKI = 4 × 10−3 mol L−1 and CNH CH COO− = 0.01 mol L−1 . 4

3

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ternary ion pairs (Cu(II)–CAS–CTAB) that increases the retention of copper ternary ion pairs on the cotton. But at higher concentrations, the emission intensities decreased due to competition of CTAB with Cu(II) to form an ion-pair with CAS (Cu(II)–CAS) [41]. 3.5. Effect of KI concentration Increasing of the ionic strength of the solution by addition of KI, does not affect the formation of the reaction products or the kinetics of the reaction [41]. The effect of salt addition on the extraction efficiency was investigated by the addition of KI in the concentration range of 0.0–1.8 × 10−2 mol L−1 . The results showed that by increasing of KI concentration up to 1.2 × 10−2 mol L−1 , the extraction efficiency increased, may be due to the effect of salt on the phase separation and retention of the ion-pair on the cotton. Consequently, a 1.2 × 10−2 mol L−1 of KI was selected for further studies. 3.6. Sample flow rate The flow rate of the sample solution in on-line SPE is one of the most important parameters affecting both the retention efficiency of the analytes and the extraction time. The effect of sample flow rate on the extraction efficiency was studied in the range of 3.2–9.6 mL min−1 . The results showed that at the flow rates greater than 6.5 mL min−1 , the emission intensity of Cu(II) ions decreased because of incomplete retention of the formed ion-pair on the SPE column. Thus, the flow rate of the sample solution was adjusted at 6.5 mL min−1 for further studies. 3.7. Effect of sample volume Breakthrough volume is another parameter that influences the preconcentration factor and reliability of analytical results of an on-line SPE system. It is very important to get satisfactory recoveries for the analytes from a large volume of the sample solutions. The effect of sample volume on the retention of copper from the sample solution was investigated. For this purpose, 25, 50, 75, 100 and 150 mL of the sample solutions containing 1.25 ␮g of copper were passed through the mini-column at the optimum flow rate. The results showed that quantitative extraction of Cu(II) ions (>90%) were obtained up to 100 mL of the sample solution. Above 100 mL, the recoveries of Cu(II) ions decreased. 3.8. Interference studies The effect of potential interfering, occurring in the environmental samples, on the on-line SPE extraction and ICP-OES determination of Cu(II) ions was investigated. Solutions containing 50 ␮g L−1 Cu(II) ions and different concentrations of the interfering ions were treated according to the proposed procedure. The tolerance limits of the coexisting ions are defined as the largest amount of the ions in the solution that decrease the recovery of the Cu(II) to less than 92% (Table 2). Most of the cations and anions examined did not interfere with the extraction of Cu(II) ions. Since the chloride and nitrate salts were employed in this study without any interference, their respective anions could pose no interference either. However, some of the species tried, such as Al(III) and Fe(III), interfered with the determination of Cu(II) ions. The interferences of Al(III) and Fe(III) ions were eliminated in the presence of 1000 ␮g mL−1 of F− and 1000 ␮g mL−1 of SCN− , as masking agents, respectively. Moreover, the potential interferences from some common matrix anions such as I− and SO4 2− were also investigated.

Table 2 Effect of interference on preconcentration and determination of Cu(II) ions. Interference

Added as

Interference to metal ion ratio

Recovery (%)

Na+ K+ Mg2+ Ca2+ Ba2+ Co2+ Mn2+ Zn2+ Pb2+ Cd2+ Ni2+ Hg2+ Cr3+ Al3+ Fe3+

NaCl KNO3 Mg(NO3 )2 ·6H2 O CaCl2 BaCl2 CoCl2 ·6H2 O MnCl2 ·4H2 O Zn(NO3 )2 Pb(NO3 )2 Cd(NO3 )2 ·4H2 O Ni(NO3 )2 ·6H2 O Hg(CH3 COO)2 Cr(NO3 )3 ·6H2 O AlCl Fe(NO3 )3 ·9H2 O

2000 2000 2000 2000 2000 1000 750 500 500 500 300 200 100 10a 10a

107 108 109 92 103 96 93 107 96 108 93 102 98 107 96

a

In the presence of masking agent (1000 ␮g mL−1 ).

They also did not interfere with the extraction of Cu(II) ions at least up to 200 mg L−1 . 3.9. Analytical performance of the method Under the optimum conditions described above, the figures of merit of the proposed method were investigated (Table 3). Dynamic linear range (DLR) was calculated using 10 spiking level of Cu(II) ions in the concentration range of 0.5–100 ␮g L−1 . For each spiking level, three replicates of analyses were performed and the calibration curve with the correlation coefficient better than 0.998 was obtained. The detection limit (DL) is obtained from CDL = kSb /m, where, k = 3, Sb is the standard deviation of six replicate blank measurements, and m is the slope of calibration curve. The DL of the proposed method for determination of Cu(II) ions under the optimum conditions was 0.04 ␮g L−1 . On the other hand, the proposed method revealed good reproducibility with the relative standard deviation (R.S.D.) of 1.3% (six replicate measurements at 10 ␮g L−1 Cu(II)). The sample throughput was 2 sample h−1 at the sample loading rate of 6.5 mL min−1 for 100 mL of sample uptake volume. The experimental enhancement factor, calculated as the ratio of the slopes of the preconcentration and direct calibration equations, was 680. The theoretical preconcentration factor, calculated as the ratio of the sample volume (100 mL) to the peak volume (0.2 mL), was 500. According to the figures of merit of the proposed method in comparison with other reported on-line solid phase extraction methods, the proposed method showed very good sensitivity and precision for determining of Cu(II) ions (summarized in Table 4). Although this method has lower sampling frequency, but it showed a better sensitivity, higher enhancement factor and lower detection limit. Moreover, in comparison with the commonly used C18 sorbents, cotton is very cheap and it can be very easily packed into the column. Table 3 Analytical performance of the proposed method for determination of Cu(II) ions. Sampling frequency (h−1 ) Preconcentration time (min) Sample flow rate (mL min−1 ) Breakthrough volume (mL) Enhancement factor Linear range (␮g L−1 ) Regression equation (␮g L−1 ) Correlation coefficient (r2 ) Detection limit (3Sb /m) (␮g L−1 ) Precision (R.S.D., n = 6) (%)

2 7.5 6.5 100 680 0.5–100 I = 782.4 C + 907.8 0.9981 0.04 1.3

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Table 4 Comparison of the figures of merit of the proposed method with the other reported solid phase extraction methods in the literature to determine the Cu(II) ions. PT (s)a

Sorbent material

Reagent

Chelex-100 or 122 resin C18 C18 C18 SiO2 -modified Gallic acid-modified Amberlite XAD-2 (functionalized) Amberlite XAD-4 (load.) Amberlite XAD-2010 (load.) PS-DVB (functionalized) Alumina (coated) Chitosan (modified) Polyurethane PTFE-turnings PCTFE-beads Oxidized MWCNTs Double-imprinted polymer Cotton

– DDC DDPA Phenathroline – – – – – – – 8-Hydroxyquinoline (derive.) APDC APDC DDPA – Chitosan-succinate CAS

a b c d

100 20 20 30 90 d

180 3000 500 240 480 90 60 60 90

SV (mL)b

f (h−1 )c

DL (␮g L−1 )

R.S.D.%

EF

Ref.

10 1.4 2.9 1.6 11.2 2000 24 25

60 120

0.07 0.2 1.4 0.3 0.2 0.86 0.54 0.06 0.05 0.93 0.3 0.2 0.2 0.05 0.07 0.32 0.83 0.04

2.2 1.3 1.5 3.0 1.4 4.31 6.1 1.2

88 19 35 32 40 200 35 300 82 43 100 19.1 170 340 250

[11] [12] [13] [14] [15] [16] [17] [18] [19] [20] [21] [22] [23] [24] [25] [26] [27] This work

d

90 27 d

18 d

d

26.4 40 10.8 12 12 11.6

d

13 d

40 36 40 30

d

d

d

3600 1800

100 100

1 2

d

5.3 4.5 0.7 2.8 1.5 1.8 2.88 6.8 1.3

d

196 680

Preconcentration time. Sample volume. Sampling frequency. Data not available.

Table 5 Determination of copper in different water samples by applying the proposed method. Sample

Real (␮g L−1 )

Tap water Well water Mineral water (1) Mineral water (2) Seawater

7.23 1.45 3.82 1.06 2.57

± ± ± ± ±

0.10 0.05 0.06 0.02 0.12a

Added (␮g L−1 )

Found (␮g L−1 )

6.0 2.0 4.0 2.0 2.0

14.05 3.54 7.62 3.18 4.22

± ± ± ± ±

0.18 0.15 0.24 0.17 0.15

Recovery%

4. Conclusion

106 103 97 103 92

In the present work, a simple, sensitive and reliable on-line SPEICP-OES method was developed for the preconcentration of copper in different water samples using cotton as solid phase extraction sorbent. Compared with the commonly used C18 sorbents, this sorbent is very cheap and it can be easily packed into the column. In addition, the retained ion pairs of Cu(II) on cotton can be easily desorbed and no carry-over is observed in the next analysis. The developed method in the present research is characterized by good precision and accuracy. The method was successfully applied to determine Cu(II) ions in the water samples and the recovery percentages for different samples were more than 90%. Accordingly, it is an easy, safe, rapid and inexpensive method for the preconcentration and determination of trace amounts of Cu(II) ions in aqueous solutions.

a Determination of copper in seawater was performed using standard addition method.

3.10. Analytical application The proposed method was applied to determine Cu(II) ions in the natural water samples (tap, deep well, sea and two different mineral waters). The accuracy of the method was investigated with the known amounts of Cu(II) ions. The obtained results are presented in Table 5. The recoveries of Cu(II) ions from the spiked samples varied in the range of 92–106%. The R.S.D. for copper determination in the examined samples varied in the range of 1.3–4.5%. The recorded

Fig. 4. Recorded peaks from the seawater sample analysis. Conditions: CCAS = 5 × 10−3 mol L−1 , sample pH 4.6, CCTAB = 2.4 × 10−3 % (w/v), CKI = 4 × 10−3 mol L−1 and CNH CH COO− = 0.01 mol L−1 . 4

3

peaks for copper determination using standard addition method in the seawater sample are shown in Fig. 4.

References [1] I.H. Scheinberg, A.G. Morell, in: G.L. Eichhorn (Ed.), Inorganic Biochemistry, vol. 1, Elsevier Press, New York, 1973. [2] N.N. Green, A. Earnshaw, Chemistry of Elements, Pergamon Press, New York, 1984. [3] C.A. Fleming, J.T. Trevors, Copper toxicity and chemistry in the environment: a review, Water Air Soil Pollut. 14 (1989) 143–158. [4] G.M. Morrison, in: G. Berthon (Ed.), Handbook on Metal–Ligand Interactions in Biological Fluids, vol. 1, Dekker, New York, 1995. [5] B. Mason, Principles of Geochemistry, 3rd ed., Wiley, New York, 1971. [6] I. Komjarova, R. Blust, Comparison of liquid–liquid extraction, solid-phase extraction and co-precipitation preconcentration methods for the determination of cadmium, copper, nickel, lead and zinc in seawater, Anal. Chim. Acta 576 (2006) 221–228. [7] Z. Fang, J. Ruzika, E.H. Hansen, An efficient flow-injection system with on-line ion-exchange preconcentration for the determination of trace amounts of heavy metals by atomic absorption spectrometry, Anal. Chim. Acta 164 (1984) 23–39. [8] Y. Yamini, M. Faraji, S. Shariati, R. Hassani, M. Ghambarian, On-line metals preconcentration and simultaneous determination using cloud point extraction and inductively coupled plasma optical emission spectrometry in water samples, Anal. Chim. Acta 612 (2008) 144–151. [9] M. Ghaedi, A. Shokrollahi, F. Ahmadi, H.M. Rajabi, M. Soylak, Cloud point extraction for the determination of copper, nickel and cobalt ions in environmental samples by flame atomic absorption spectrometry, J. Hazard. Mater. 150 (2008) 533. [10] M. Ghaedi, M.R. Fathi, A. Shokrollahi, S. Gharaghani, M. Soylak, Cloud point extraction for the determination of copper ion in environmental samples, Quim. Nova. 31 (2008) 70–74.

1388

M. Faraji et al. / Journal of Hazardous Materials 166 (2009) 1383–1388

[11] M. Ghaedi, M.K. Amini, A. Rafi, S. Gharaghani, A. Shokrolahi, Adsorptive stripping voltammetric determination of copper (II) ion using phenyl pyridyl ketone oxime, Annal. di Chim. 95 (2005) 457–464. [12] M. Moors, D.L. Massart, R.D. McDowall, Analyte isolation by solid-phase extraction (SPE) on silica-bonded phases—classification and recommended practices, Pure Appl. Chem. 66 (1994) 277–304. [13] V. Camel, Solid phase extraction of trace elements, Spectrochim. Acta Part B 58 (2003) 1177–1233. [14] Z. Fang, T. Guo, B. Welz, Determination of cadmium, lead and copper in water samples by flame atomic-absorption spectrometry with preconcentration by flow-injection on-line sorbent extraction, Talanta 38 (1991) 613–619. [15] R. Ma, W. van Mol, F. Adams, Determination of cadmium, copper and lead in environmental samples. An evaluation of flow injection on-line sorbent extraction for flame atomic absorption spectrometry, Anal. Chim. Acta 285 (1994) 33–43. [16] A. Ali, X. Yin, H. Shen, Y. Ye, X. Gu, 1,10-Phenanthroline as a complexing agent for on-line sorbent extraction/preconcentration for flow injection-flame atomic absorption spectrometry, Anal. Chim. Acta 392 (1999) 283–289. [17] F. Xie, X. Lin, X. Wu, Z. Xie, Solid phase extraction of lead(II), copper(II), cadmium(II) and nickel(II) using gallic acid modified silica gel prior to determination by flame atomic absorption spectrometry, Talanta 74 (2008) 836–843. [18] W. Ngeontae, W. Aeungmaitrepirom, T. Tuntulani, Chemically modified silica gel with aminothioamidoanthraquinone for solid phase extraction and preconcentration of Pb(II), Cu(II), Ni(II), Co(II) and Cd(II), Talanta 71 (2007) 1075–1082. [19] 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. [20] M.C. Yebra, N. Carro, M.F. Enríquez, A. Moreno-Cid, A. García, Field sample preconcentration of copper in seawater using chelating minicolumns subsequently incorporated on a flow-injection–flame atomic absorption spectrometry system, Analyst 126 (2001) 933–937. [21] C. Duran, A. Gundogdu, V.N. Bulut, M. Soylak, L. Elci, H.B. Sentürk, M. Tüfekci, Solid-phase extraction of Mn(II), Co(II), Ni(II), Cu(II), Cd(II) and Pb(II) ions from environmental samples by flame atomic absorption spectrometry (FAAS), J. Hazard. Mater. 146 (2007) 347–355. [22] 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/FAAS copper determination in waters, Talanta 67 (2005) 121–128. [23] S. Dadfarnia, A.M.H. Shabani, F. Tamaddon, M. Rezaei, Immobilized salen (N,Nbis (salicylidene ethylenediamine) as a complexing agent for on-line sorbent extraction/preconcentration and flow injection–flame atomic absorption spectrometry, Anal. Chim. Acta 539 (2005) 69–75. [24] A.O. Martins, E.L. da Silva, E. Carasek, M.C.M. Laranjeira, V.T. Fávere de, Sulphoxine immobilized onto chitosan microspheres by spray drying: application for metal ions preconcentration by flow injection analysis, Talanta 63 (2004) 397–403. [25] A.N. Anthemidis, G.A. Zachariadis, J.A. Stratis, On-line preconcentration and determination of copper, lead and chromium(VI) using unloaded polyurethane foam packed column by flame atomic absorption spectrometry in natural waters and biological samples, Talanta 58 (2002) 831–840.

[26] A.N. Anthemidis, G.A. Zachariadis, J.A. Stratis, On-line solid phase extraction system using PTFE packed column for the flame atomic absorption spectrometric determination of copper in water samples, Talanta 54 (2001) 935–942. [27] A.N. Anthemidis, K.-I.G. Ioannou, Evaluation of polychlorotrifluoroethylene as sorbent material for on-line solid phase extraction systems: Determination of copper and lead by flame atomic absorption spectrometry in water samples, Anal. Chim. Acta 575 (2006) 126–132. [28] J.P. Xiao, Q.X. Zhou, H.H. Bai, Preconcentration of copper with multi-walled carbon nanotubes pretreated by potassium permanganate cartridge for solid phase extraction prior to flame atomic absorption spectrometry, Chin. Chem. Lett. 18 (2007) 714–717. [29] M. Ghaedi, F. Ahmadi, M.R. Baezat, J. Safari, Preconcentration and extraction of copper(II) on activated carbon using ethyl-2-quinolyl-ß(p-carboxyphenyl hydrazone) dioxo propionate, Bull. Chem. Soc. Ethiop. 22 (2008) 331– 338. [30] M. Ghaedi, F. Ahmadi, H. Karimi, S. Gharaghani, Preconcentration and extraction of copper on activated carbon using 4-amino-2, 3-dimethyl-1-phenyl-3pyrazoline or 4-(4-methoxybenzylidenimin) thiophenole, J. Korean Chem. Soc. 50 (2006) 23–31. [31] E. Birlik, A. Ersoz, A. Denizli, R. Say, Preconcentration of copper using doubleimprinted polymer via solid phase extraction, Anal. Chim. Acta 565 (2006) 145–151. [32] H.M. Choi, H.J. Kwon, J.P. Moreau, Cotton nonwovens as oil-spill cleanup sorbent, Text. Res. J. 63 (1993) 211–218. [33] H.M. Choi, R.M. Cloud, Natural sorbent in oil-spill clean, Environ. Sci. Technol. 26 (1992) 772–776. [34] M.M. Radetic, D.M. Jocic, P.M. Jovancic, Z.L.J. Petrovic, H.F. Thomas, Recycled wool-based nonwoven material as an oil sorbent, Environ. Sci. Technol. 37 (2003) 1008–1012. [35] G. Deschamps, H. Caruel, M.E. Borredon, C. Bonnin, C. Vignoles, Oil removal from water by selective sorption on hydrophobic cotton fibers. Study of sorption properties and comparison with other cotton fiber-based sorbents, Environ. Sci. Technol. 37 (2003) 1013–1015. [36] M. Gonzalez, M. Gallego, M. Valcarcel, Determination of natural and synthetic colorants in prescreened dairy samples using liquid chromatography-diode array detection, Anal. Chem. 75 (2003) 685–693. [37] J.-F. Liu, Y.-G. Chi, G.-B. Jiang, C. Tai, J.-T. Hu, Use of cotton as a sorbent for on-line precolumn enrichment of polycyclic aromatic hydrocarbons in waters prior to liquid chromatography determination, Microchem. J. 77 (2004) 19–22. [38] O. Valcl, I. Nemcova, V. Suk, Handbook of Triarylmethane Dyes: Spectrophotometric Determination of Metals, C.R.C Press, Boca Raton, FL, 1985. [39] A. Shokrollahi, M. Ghaedi, H. Ghaedi, Potentiometric and spectrophotometric studies of copper(II) complexes of some ligands in aqueous and nonaqueous solution, J. Chin. Chem. Soc. 54 (4) (2007) 933–940. [40] A. Semb, F.J. Langmyhr, Complex formation of copper(II) with chromazurol S, Anal. Chim. Acta 35 (1966) 286–292. [41] I. Nemcova, V. Tomankova, P. Rychlovsky, Non-extraction batchwise and FIA determination of cationic and nonionic surfactants using Cu(II)–chromazurol S–surfactant complexes, Talanta 52 (2000) 111–121.