Model for verification of measurement results in electrothermal atomic absorption spectrometry

Abstract

We present a practical application of a phenomenological model for physicochemical atomization processes in determining heavy metal content by electrothermal atomic absorption spectrometry. Comparison of the analysis results with the NAHRES-33 (IAEA/AL/079) certificate of composition confirms the feasibility of using the proposed procedure in analysis of lichen materials. As the criterion for the reliability of the analysis results, we take the closeness of the values for the sample atomization parameters to the atomization parameters of the calibration solutions obtained, using a model for the analytical signal. We demonstrate application of the proposed procedure using as an example monitoring of heavy-metal air pollution by the lichen indication method.Keywords: atomic absorption spectrometry, electrothermal atomization, modeling of an analytical signal, energy of formation of the free atoms, lichen indication.Introduction. As we know, the atomic absorption spectrometry method is a relative method and requires preliminary calibration of the instrument using solutions with known content of the analyte element. For correct analysis, the matrix of this calibration solution must be as close as possible to the sample matrix with respect to chemical composition. In cases when the composition of the matrix is complicated or unknown, generally standard samples (reference standards) are used.If the necessary standards are not available, for calibration of the instrument the method of standard additions is used, which has certain limitations since the additions cannot always be introduced in the same chemical form as the analyte in the sample [1,2]. In this case, analyte losses when a volatile compound is formed with the matrix or if it is incompletely atomized when a refractory compound is formed with the matrix can lead to substantial analysis error.In order to avoid errors associated with the influence of the chemical matrix and to identify the reasons for distortion of the analytical signal, a phenomenological model for physicochemical atomization processes can be utilized [3] which we have successfully used for monitoring the reliability of impurity determination in reactor zirconium [4]:

Atomic spectrometry update. Advances in atomic spectrometry and related techniques

“…Ilyashenko et al 151 describe a model used for the verification of measurements made in ETAAS. The basis of the approach involves comparing the atomisation parameters obtained from samples and from calibration standards.…”