Total elemental composition analysis of soil samples using the PIXE technique Oyuntsetseg Bolormaa a, * , Jamsranjav Baasansuren a , Katsunori Kawasaki b , Makiko Watanabe a , Toshiyuki Hattroi c a Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8502, Japan b Department of Physics, Tokyo Institute of Technology, 2-12-1, Ookayama, Meguro-ku, Tokyo 152-8551, Japan c Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, 2-12-1, Ookayama, Meguro-ku, Tokyo, Japan Received 14 July 2006; received in revised form 30 May 2007 Available online 22 June 2007 Abstract The determination of major and trace element contents in soils was developed by acid digestion method combined with particle- induced X-ray emission spectrometry (PIXE). The digestion of soils was achieved by using nitric acid (HNO 3 ), hydrochloric acid HCl and hydrogen peroxide (H 2 O 2 ) with repeated additions. A 20 lL aliquot from the digested samples was evaporated on the Nucle- pore Track-Etch Membrane and irradiated by the 2.5 MeV proton beam from the single-end type Van de Graaff accelerator. The accu- racy of this methodology was estimated based on series of measurements done for a reference material of soil CRM 023-050. The proposed experimental procedure was shown to have good reproducibility of the experimental results. The corresponding limits of detec- tion (LODs) for Na, Mg, Al, P, S, Cl, K, Cr, Mn, Fe, Ni, Cu, Zn, As, Sr, Mo and Cd were estimated. Other soil characteristics such as total carbon (TC) and nitrogen (TN) content, pH and electrical conductivity (EC) were also measured. Ó 2007 Elsevier B.V. All rights reserved. PACS: 29.30.Kv; 89.60.+x Keywords: PIXE; Soil; Heavy metals; Mining 1. Introduction The content of heavy metals in soils and sediments is an important characteristic in environmental monitoring essential for soil genesis. Many methods have been devel- oped to determine the amounts of trace metals in soils. In most cases, digestion of the soil samples is required to determine the total amount of trace metals in soils using mono-elemental (AAS and GFAAS) [1,2] or multielemental spectroscopic techniques (ICP-OES and ICP-MS) [3,4]. To obtain the necessary information on the elemental composi- tions several digestion methods are applied such as ASTM D5258-92 [5], US-EPA method 3050B [6], US-EPA method 3051 [7] and US-EPA method 3052 [8]. The choice for a spe- cific combination of digestion and spectroscopy is dictated by detection limits and requirements for compatibility with different acid mixtures for sample dissolution and low sen- sitivity to matrix effects. Especially important here is to achieve soil sample solutions compatible with different salt mixtures in the same solvent. The particle induced X-ray emission (PIXE) in combination with acid digestion seems to be advantageous since it almost eliminates matrix effects inherent in solid sample analysis. This technique allows the simultaneous analysis for particularly all elements heavier than Na with a reasonable acquisition time. Moreover, it is the multi-elementary analysis method which is the neces- sary property for the current study. The present paper deals with developing the methodology of the PIXE spectrometry 0168-583X/$ - see front matter Ó 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.nimb.2007.05.033 * Corresponding author. Tel./fax: +81 459245533. E-mail address: bolormuis@yahoo.com (O. Bolormaa). www.elsevier.com/locate/nimb Nuclear Instruments and Methods in Physics Research B 262 (2007) 385–390 NIM B Beam Interactions with Materials & Atoms