Determining trace amounts of nickel in plant samples by neutron activation analysis
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Determining trace amounts of nickel in plant samples by neutron activation analysis B. Canion • S. Landsberger
Received: 22 July 2012 / Published online: 15 August 2012 Ó Akade´miai Kiado´, Budapest, Hungary 2012
Abstract Neutron activation analysis of plant samples for trace amounts of nickel has applications in various fields. Landsberger and Robinson (Trans Am Nucl Soc 102: 187–188, 2010) found their measurement of the concentrations of nickel for different NIST reference materials to be significantly greater than the certified values when measuring nickel from the 810.8 keV gamma ray that comes from 58Co from the 58Ni(n,p) reaction. They determined that this overestimation was due to a significant interference by the presence of 152Eu at 810.5 keV, and presented a method for correcting this interference. Their method involved a long thermal irradiation and correction of gamma ray counts based on the 1,408 keV belonging to 152 Eu. This paper presents an alternative approach, which involves irradiating the samples with epithermal neutrons, which suppressed the 152Eu to the point of being negligible for samples with low levels of europium. Both methods were determined to work well for the identification of nickel concentrations by neutron activation analysis. Keywords analysis
Nickel Nickel in plants Neutron activation
Introduction Nickel is commonly found in trace amounts in biological samples, especially in plant life. The analysis of nickel and other metals in plants is a common practice that is applicable to many fields, such as the study of contaminant uptake by B. Canion S. Landsberger (&) Nuclear Engineering Teaching Lab, University of Texas at Austin, R-9000, Austin, TX 78712, USA e-mail: [email protected]
plants for the purpose of phytoremediation [1], or the study of the mobility of metals from pollution [2]. In a higher order of plants known as vascular or tracheophytes, nickel is absorbed by plants in the form of Ni?2 ion. While high concentrations of nickel can be considered toxic, it is also an essential element and activates several enzymes involved in a variety of processes [3]. Instrumental neutron activation analysis (INAA) is commonly used to analyze trace elements in environmental and biological samples, and is excellent for multi-elemental and non-destructive analysis of trace and major elements [4, 5]. However, nickel is not easily measurable by INAA due to there being few neutron interactions which lead to gamma-ray emitting decays. In a previously published paper by the co-author [6], the concentrations of nickel for different NIST reference materials were calculated to be significantly greater than the certified values in a routine quality assurance evaluation using thermal NAA. A perusal of the decay scheme literature revealed a substantial interference on the determination of nickel by the presence of europium. The overestimation varies to the ratio of concentrations of europium to nickel that are present in the reference materials. A method for correcting this overe
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