Expanding the range of determination of elements on the Grand-AAS atomic absorption spectrometer using several of their absorption lines

Abstract

One limitation of atomic absorption spectrometry is the narrow range of measurable concentration (1–2 orders of magnitude). In simultaneous multi-element analysis, this may require multiple dilutions of the sample to determine several elements with different concentrations in the sample. Possible ways to expand the range are to linearize the calibration curve by correcting the integral of the absorption signal or to use absorption values on the line wing as an analytical signal and plot several graphs along one line at different distances from its center. Both methods have their drawbacks. We propose another method for expanding the measurable concentration range by using less sensitive absorption lines of elements. A number of elements are identified that have a sufficient number of lines with different sensitivities. The proposed method is compared with the method of linearization of the calibration graph and the calculation of the absorption signal on the line wing. Using as an example Co and Ni, which have sufficiently rich absorption spectra, we have shown the possibility of expanding the measurable concentration range by using several absorption lines: for cobalt, the range is expanded to six orders of magnitude, and for nickel, to five orders of magnitude. Calibration curves are plotted in the concentration ranges 0.24–250.000 μg/L for cobalt and 1.9–250.000 μg/L for nickel. The calibration error is lower than that of the linearization method: 5% against 25 % for cobalt and 4% against 24% for nickel. Thus, the proposed method can be used for simultaneous multielement determination in a wide range of concentrations without diluting the sample.