Fig. 1 . Scheme of principle work of ICP-OES spectrometer

1. COMPARISON OF DIFFERENT ANALYTICAL TECHNIQUES FOR ENVIRONMENTAL MONITORING OF CONTAMINATED SOILSMetodi Mladenov, Daria Ilieva University of Chemical Technology and Metallurgy – Sofia, Bulgaria, 1756, Sofia, 8 “St. Kliment Ohridski” blvd., e-mail: mladenov@uctm.edu IntroductionEnvironmental monitoring of contaminated soils is a different task, because of the using of different analytical techniques for analysis depending on the type of the contaminants. There are many types of analysis which are used for preparation of the samples. Still the most used and standardized in many countries is method for extraction with “aqua regia”, and next analysis through inductively coupled plasma (ICP) technique. Some other analytical technique is the wave dispersive X-ray fluorescence (WD-XRF) analysis. That method has very high possibilities for determination of concentration of heavy metals and metalloids in different kinds of samples and has some advantages over the other analytical methods. In current work the done experiments for environmental monitoring of contaminated soil are described. The presence and concentrations of elements Cu, Fe, Mn, Pb, As, Zn, Ni and Cr, through “aqua regia” extraction and ICP-OES (optical emission spectrometry) analysis and WD-XRF analysis are investigated. Experimental Nineteen samples from region of old metallurgical plant, which proven are contaminated with heavy metals and metalloids, are analyzed. The presence and concentrations of elements Cu, Fe, Mn, Pb, As, Zn, Ni and Cr, through “aqua regia” extraction and ICP-OES analysis and XRF analysis are investigated.Schemes of principal work of the two techniques are showed on figs. 1 and 2. Comparison of the performances of the two used method is showed in Table 1. Fig. 1.Scheme of principle work of ICP-OES spectrometer The sampling and sample preparation for XRF analysis are detailed in [1]. The samples were analysed with a Carl Zeiss, Jena (Germany) “VRA 20” wavelength-dispersive XRF spectrometer. Working conditions: X-ray tube with Rh anode; current 50 mA; voltage 35 kV; crystalline analyzer LiF200; detector SC and FC; collimator 0.70; measuring time of each step 30 s; measuring reiteration 3 times. For the quantitative analysis measurements were performed at the characteristic line for each analyte [2]. The extraction with “aqua regia” solution was done according to [3]. It was used Prodigy ICP_OES, Teledyne, Leeman Labs apparatus with next plasma operation conditions: coolant gas – 18 L/min; auxiliary gas – 0.5 L/min; nebulizer gas – psi; power – 1,2 kW; sample uptake time – 30 sec. Fig. 2.Scheme of principle work of WD-XRF spectrometer Results Obtained intervals for results from both methods are showed in table 2. Obtained results haven’t good accordance between themselves. The reason for that can be contain in a different sample preparation procedure for both method. Table 1. Comparison of performances of the used methods in analysis of current samples Table 2. Obtained intervals of concentrations by the two methods. *The new apparatus for WD-XRF have comparable instrumental performance with used in current analysis ICP-OES technique. ** time for five parallel measurements of one sample. • On the basis of the obtained results, next conclusions may be drawn: • The obtained results from the two methods are with good accordance for elements As, Zn, Ni and Mn. • Sample preparation for ICP-OES analysis needs from special treatment, which not every time is appropriate for treatment of the analyzed soil samples. For example when the carbonate soils are treated often it is necessary double portion of aqua regia to be used. • Used ICP-OES analysis have very high accuracy, high sensitivity and scale of operation up to ppm, which is advantage to the used apparatus for WD-XRF. That advantage can be equalize if for WD-XRF analysis s use new generation of apparatus. • Even used old generation of apparatus for WD-XRF analysis, the advantages of this analysis is consist in lower time for sample preparation and elimination of error which can be permit form stage of extraction. • References • Mladenov M., Jordanov J., Pelovski Y., X-ray spectroscopy analysis of soils in the region of “Eliseina”metallurgical plant, Journal of Environmental Protection and Ecology (2010) 11 (4), 1246-1252. • Mladenov M., Jordanov J., Ivanova E.,X-ray spectroscopy analysis of soils in the region of Eliseina metallurgical plant – Part 2, Journal of Environmental Protection and Ecology (2012) 13 (3A), 1887-1895. • ISO 11466 :1995. Soil quality – Extraction of trace elements soluble in aqua regia. Acknowledgements This poster has been produced with the financial assistance of the European Social Fund, project number BG051PO001-3.3.06-0014. The author is responsible for the content of this material, and under no circumstances can be considered as an official position of the European Union and the Ministry of Education and Science of Bulgaria