Experimental design and z -score results are useful tools for optimizing instrumental neutron activation analysis proced
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Experimental design and z‑score results are useful tools for optimizing instrumental neutron activation analysis procedures Uanda P. M. Santos1 · Felipe R. Lourenço2 · Edson G. Moreira1 Received: 10 December 2019 © Akadémiai Kiadó, Budapest, Hungary 2020
Abstract In this study 2k experimental designs were used for the optimization of an instrumental neutron activation analysis method for the determination of bromine, chlorine, magnesium, manganese, potassium, sodium and vanadium in biological matrix materials. Depending on radionuclide half-lives, 2 3 or 2 4 experimental designs were used with irradiation time, sample–detector distance, counting time and sample decay time as factors. Gamma ray spectrometer, comparator mass fraction and sample mass were kept constant. Optimized irradiation and measurement conditions were established based on the experimental design results that used z-scores as response on a reference material for the various elements and experimental conditions. Keywords Neutron activation analysis · Experimental design · Factorial design · z-Score · Method validation
Introduction Design of experiments (DOE) or experimental design is a multivariate methodology of experiment planning used for the optimization of methods and processes. Regardless of the model used, DOE presents a number of advantages over the use of a univariate (conventional) methodology, such as the possibility of reduction in the number of rounds or experiments; indication of the major or crucial variable or variables of the investigated process and the way the most diverse variables correlate to each other [1]. Experimental design, also called factorial design, represents a set of tests established with scientific and statistical criteria in order to determine the influence of several variables on the results of a given system or process [2]. In a previous study at our institute, a 2 3 experimental design was carried out with biological and geological samples, aiming the analysis of As, Co, Cr, Sb, Sc and Zn by instrumental neutron activation analysis (INAA), using the * Edson G. Moreira [email protected] 1
Research Reactor Center, Nuclear and Energy Research Institute, Av. Prof. Lineu Prestes, 2242, São Paulo, SP 05508‑000, Brazil
School of Pharmaceutical Sciences, University of São Paulo, Av. Prof. Lineu Prestes, 580, São Paulo, SP 05508‑000, Brazil
2
corresponding long lived radionuclides [3]. The idea was to optimize the experimental conditions in order to carry out the formal process of method validation at the laboratory. As far as we know, DOE was not applied in any other nuclear analytical technique up to now and the purpose of this study was to apply the 2 3 experimental design and other types of planning, such as 2 4, in the optimization of an INAA method using short time irradiations at a pneumatic system of the IEA-R1 reactor at IPEN—CNEN/SP. In this case, Br, Cl, K, Mg, Mn, Na and V mass fractions were determined by INAA in a biological matrix reference material and commercial software was used to e
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