A method for optimizing the settings of a LIBS device aimed at achieving the maximum intensity of analytical lines of the analyte of constant composition is considered using probabilistic-deterministic design of experiments (PDDE). A mixture of Cr, Mn, Fe, Co, and Ni oxides homogenized and diluted by fusion with a lead-phosphate mixture is used as an analyte. It is shown that data of mathematical processing of 25 spectra by the PDDE method can be used to develop mathematical models which relate the line intensity with the energy of the laser pumping lamp, the lag time of the first and second Q-switches, the time delay of the exposure onset, and the total exposure time. The use of the geometric mean and mathematical model in the form of the product of the partial dependences leads to a good correlation between the calculated and experimental values of the intensity for all the considered spectral lines. The simulation results presented for 16 analytical lines of Cr, Mn, Co, and Ni illustrate the applicability of the method under consideration. The experimentally achieved maximum intensities of analytical lines in the matrix of lead-phosphate glass differ from those calculated using the obtained models by 7 – 12 %. There is a linear correlation between the experimental and calculated values of the intensity at R2 = 0.99 and an inclination angle close to 45°. The spectra recorded during the experiment can be used for optimization of other parameters, e.g., the signal-to-noise ratio. The simplicity of calculations and relatively small number of tests in the optimization experiment make the PDDE a promising method for optimizing the LIBS parameters.

The problems of improving the chemometric characteristics of spectral methods of analysis are being intensively studied throughout the world. These problems are especially significant in the field of laser atomic emission spectrometry. In the article, it is proposed to use sample homogenization by fusion with sodium tetraborate. The example of iron in a mixture of oxides consisting of Fe2O3, PbO, CuO, CdO and ZnO has shown that fusion provides advantages over pressing, consisting in increasing the intensity of the spectral lines and increasing the accuracy of the concentration / intensity correlation, as well as an increase in the total number of spectral lines, which can be calibrated satisfactorily. Using the probabilistic-deterministic planning of the experiment and using the composite factor, it is shown that fusion substantially weakens the interrelation of the intensity of the spectral line with the instrument settings, which simplifies the choice of the spectrum registration regime. The observed regularities are explained by the high homogeneity of the vitreous samples, the more complete evaporation of the sample in the laser spark and the absence of interference in the form of a neat atomized sample, an increase in the density (and hence the concentration) of the sample. In the course of the experiments it was additionally established that for melting specimens, it was necessary to use the crucibles from alumina with caution. They dissolve rather quickly in the melt of tetraborate. Nickel crucibles can be used only if nickel is not among the elements that are determined in the sample. Based on the results of the study, there was made a conclusion about the need study of the proposed methodology and its extension to other elements of the periodic system for further.

This article describes the commodity polyethylene pyrolysis at temperatures 300-370 degrees C. It was shown that the yield of gaseous products in these conditions increases with increasing temperature and by prolonging the process. Dependencies are described by using stochastic determinated design of experiments. The formal activation energy of the pyrolysis process (7.7 kJ/mol) with producing gaseous components was also determined.

The possibility of using one-way dispersion analysis ANOVA in this article is discribed, for the evaluation of statistical significance of the empirical dependensis which was gift by using of stochastic determinated design of experiments (SDDE). It is shown that use of ANOWA can disambiguate the interpretation of some results.