SELECTIVE EXTRACTION AND SPECTROFLUORIMETRIC DETERMINATION SELECTIVE EXTRACTION AND SPECTROFLUORIMETRIC DETERMINATION OF METAL IONS IN NATURAL AND INDUSTRIAL WATERS OF METAL IONS IN NATURAL AND INDUSTRIAL WATERS BRACH-PAPA Christophe, THERAULAZ Frédéric, BOUDENNE Jean-Luc and COULOMB Bruno Université de Provence, Laboratoire de Chimie et Environnement Case 29 - 3 Place Victor Hugo, 13331 Marseille Cedex 3, FRANCE Tél : +33 4 91 10 63 76 - Fax : +33 4 91 10 63 77 E-mail : lceeau@up.univ-mrs.fr The analytical characteristics for Al 3+ determination are represented in the following table : A study of interference of foreign ions, commonly available in aquatic samples, in the determination of [Al 3+ ]= 150 ppb has been carried out in binary mixture. The criterion for interferences was fixed at ±5% of the average fluorescence intensity calculated for the established level of Aluminium. Metals Tolerated concentrations Fe 3+ 600 μg L -1 Cu 2+ 800 μg L -1 Ca 2+ 150 mg L -1 Na + no interference in 0-150 mg L -1 range K + no interference in 0-20 mg L -1 range Mg 2+ no interference in 0-100 mg L -1 range Mn 2+ no interference in 0-200 μg L -1 range Cr 3+ no interference in 0-100 μg L -1 range Cr 6+ no interference in 0-100 μg L -1 range Fe 2+ no interference in 0-1 mg L -1 range Co 2+ no interference in 0-100 μg L -1 range Ni 2+ no interference in 0-100 μg L -1 range Cd 2+ no interference in 0-100 μg L -1 range Linearity range 0-300 ppb Limit of detection 2.2 ppb Limit of quantification 2.8 ppb Relative stantard deviation (evaluated for [Al 3+ ] = 150 ppb) 0.96 % The eluted metals from the SPE column are fluorimetricaly detected with an organic ligand, 8-hydroxyquinoline-5-sulfonic acid (HQS), by formation of a fluorescent complex. a selective chelating compound, 2-hydroxy-benzoic acid, in order to obtain a specific material for Al 3+ extraction. The sample previously buffered at pH = 5,5 was injected through the column with a peristaltic pump (flow rate 2 ml/ min). Then collected metals were eluted with HNO 3 . Scheme of the proposal extractive column. Stationnary phase : Poly(styrenedivinylbenzene) loaded with selective extractant as sorbent phase. Polyethylene frits. (0.2 μm) Polypropylene tube. COOH Fluorescence excitation and emission spectra of [HQS-Al]. 160 180 ). Emission spectrum excitation spectrum During the last few decades, increasing attention has been focused on metallic pollution of natural environments and particularly in aqueous systems. Most of the existing analytical techniques commonly used for metal ion determination are very time consuming and do not allow “on line” or even “in situ” monitoring of water quality. It’s the reason why there is a new field of interest for the development of analytical tools well adapted for acquisition of results in real -time. The aim of this study is to proposed an analytical procedure for metal ion determination in aqueous samples based on spectrofluorimetric detection. This optical procedure has been selected according to its properties such as, low cost, simplicity of development and versatility of use. Moreover, this method allows metal ion determinations at very low levels (ppb range). In order to optimize the analytical method, spectrofluorimetric detection has been associated with a solid phase extraction procedure. PRINCIPLE : The proposed method is based both on a selective extraction on a specific column, and on a fluorimetric detection. • Firstly, the extraction is achieved by using a column made of polymeric materials functionalized with a very selective chelating agent of the studied analyte as stationary phase. INTRODUCTION : ANVAR Contract # J9810026U/JJ Cd no interference in 0-100 μg L range Zn 2+ no interference in 0-1 mg L -1 range The proposal procedure has been validated on tap water by the use of the standard addition method. CONCLUSION AND PERSPECTIVES : The proposed procedure is satisfactory for the determination of Al 3+ in natural and tap water at ppb levels without any interference from other common metal ions. Currently, automated system based on a sequential injection analysis procedure is being developed with a view to design an adapted process for in-situ determination of aluminium. This device should be suitable for the determination of other metal ions . y = 1,0532x + 7,5521 R 2 = 0,9919 0 50 100 150 200 250 300 0 50 100 150 200 250 300 Added [Al 3+ ] concentration in tap water (μg L -1 ). Estimated [Al 3+ ] concentration by the spectrofluorimetric method (μg L -1 ). Correlation between the fluorescence intensity and the standard addition method. BIBLIOGRAPHY : BEAUVAIS R.A. and ALEXANDRATOS S.D., 1998, Reactive & Functional Polymers, 36, 113-123. MOYERS E.M. and FRITZ J.S., 1977, Analytical Chemistry, 49, 418-423. SOROKA K., VITHANAGE R.S., PHILLIPS D.A., WALKER B. and DASGUPTA P.K., 1987, Analytical Chemistry, 59, 629-636. Fluorescence intensity of [HQS-Al] was measured in a quartz cell (past length : 10 mm), at an excitation wavelength of 354 nm and an emission wavelength of 482 nm. For the fluorescent measurements, solutions containing Al 3+ have been previously buffered at pH = 4. The calibration graph obtained with the proposal procedure is linear up 1.5 mg L -1 of Al 3+ in the aqueous phase. For specific application in natural or in tap waters, a specific calibration curve for 0 μg L -1 up to 300 μ g L -1 has been realized. 0 20 40 60 80 100 120 140 160 250 300 350 400 450 500 550 wave length (nm). Fluorescence intensity (u.a) y = 0,5974x + 3,7258 R 2 = 0,9971 0 20 40 60 80 100 120 140 160 180 200 0 50 100 150 200 250 300 350 Concentration in Al 3+ (μg L -1 ). Fluorescence intensity (u.a.). Correlation between the fluorescence intensity and [Al 3+ ] concentration. ANALYTICAL FEATURES OF THE METHOD. APPLICATION OF THE PROCEDURE : EXAMPLE TO Al 3+ DETERMINATION : In order to illustrate the proposed method, an application on aluminium determination has been investigated. The selective extraction is achieved by using an extractive column specially designed for this application. The column is made of poly(styrenedivinylbenzenze) packed in a polypropylene tube between two polyethylene frits. This polymeric material has been functionalized with • Secondly, the eluted metals from the SPE column are fluorimetricaly determined with an organic ligand by formation of fluorescent complexes. • Thirdly, exploitation of the resulting fluorimetric spectrum have been carried out with ever a mono-wavelength or multi-wavelength procedure depending on the application. Scheme of the proposal method. Sample . Isolation of analytes of interest. Waste Step 1 Step 1 : Selective : Selective extraction extraction. Step 2 Step 2 : Elution : Elution and detection and detection Eluant Detector Fluorescent ligand + buffer solution 0 4 8 12 16 20 330 350 370 390 410 430 REF1 REF2 REF3 Se Step 3 Step 3 : Exploitation of the : Exploitation of the fluorescent spectrum. fluorescent spectrum. View publication stats View publication stats