Interferences and Methods for Their Elimination in the Determination of Lanthanum as LaO by Laser-Enhanced Molecular Flame Ionization Spectrometry

Interfering effects of some elements on the determination of lanthanum as LaO in a natural gas–air flame by laser-enhanced molecular ionization spectrometry were studied. It was demonstrated that easily ionized elements (Li, K, Na, Mg) exert an ionization effect; in addition, sodium introduces spectral interference. Techniques were proposed for the elimination of these interfering effects.     

Comparison of figures of merit for fluorimetric analysis of rhodamine complexes of gallium and indium by excitation with pulsed laser and by xenon arc sources

Optimum conditions have been established for formation and extraction of indium-Rhodamine complexes, and limits of detection found for fluorimetric determination of gallium and indium by means of Rhodamine dyes, using the excitation with pulsed laser and xenon arc sources.     

Determination of glucose and lactose in food products with the use of biosensors based on Berlin blue

The immobilization of enzymes into polyelectrolyte membranes with the use of organic solvents was applied to the development of the biosensing elements of biosensors. The following domestically produced preparations were used: the enzymes glucose oxidase and β-galactosidase and a perfluorosulfonated polymer. The compositions of mono-and bienzymic polyelectrolyte membranes were optimized. The glucose and lactose biosensors based on Berlin blue (as a signal transducer) and polyelectrolyte membranes exhibited high sensitivity, low detection limits, and fast response. The results of the analysis of milk whey in a flow-injection system that included biosensors completely correlated with measurement data obtained by a standard chromatographic technique.     

Nonlinear normalization for laser-enhanced ionization spectrometry with laser sampling into a flame

The conditions for the appearance of a significant linear correlation between laser-enhanced ionization and reference signals are found. The parameters of this correlation (polynomial coefficients) are suggested to be used as a normalized analytical signal. The use of nonlinear correlation makes it possible to extend the range of ablation laser energies.     

Highly sensitive sorption-luminescence determination of trace europium with preconcentration on silica chemically modified with iminodiacetic acid

Features of a sorption-luminescence method for the determination of trace europium were studied. The method includes the preliminary sorption of europium at pH 7.1 from solutions with silica chemically modified with iminodiacetic acid, the subsequent treatment of the sorbent with 2-thenoyltrifluoroacetone at pH 8.0, and the measurement of the intensity of luminescence of the surface three-component europium complex at 613 nm. The effect of moisture as the quencher of luminescence of the surface europium complex was studied, and techniques for its removal were proposed. Sorption in the static mode provides the detection limit of europium of 7 × 10⁻⁵ μg/mL. The calibration plot is linear in the range of two orders of magnitude of europium concentration in solutions. The relative standard deviation in the determination of 1.5 × 10⁻² μg/mL europium is 5%. In the dynamic mode of sorption from 1000 mL of an analyzed solution with the use of sorption-desorption, the detection limit of europium of 8 × 10⁻⁷ μg/mL was attained. Original Russian Text ? R.D. Voronina, N.B. Zorov, 2007, published in Zhurnal Analiticheskoi Khimii, 2007, Vol. 62, No. 3, pp. 230–237.     

Books on spectrochemical analysis

Critique and Bibliography

Books on spectrochemical analysis     

Determination of copper content in soils and ores by laser-induced breakdown spectrometry

Features of electromagnetically induced transparency (EIT) in potassium vapors at the D₁ line of the ³⁹K isotope are studied. EIT resonances with a subnatural width of 3.5 MHz have been recorded upon excitation by two independent narrow-band diode lasers in a 1-cm-long cell filled with a natural mixture of potassium isotopes and buffer gas. The splitting of EIT resonances in potassium vapors in longitudinal and transverse magnetic fields has been studied for the first time. The splitted components also have a subnatural width. The smallness of the coupling factor of the hyperfine structure in ³⁹K atoms leads to a transition to the Paschen—Back regime at relatively weaker magnetic fields than in the case of Cs, Rb, and Na atoms. Practical applications of the phenomena under study are noted. The theoretical model well explains the experiment.     

Correlation between properties of a solid sample and laser-induced plasma parameters

To investigate the influence of mechanical properties of a solid sample on the laser-induced plasma parameters (temperature and mass ablated) a number of aluminum–lithium alloys and lithium ferrites with different microstructure and composition have been studied. The specific approach to estimate excitation temperature for low-resolution emission spectra has been developed. The main limitations of this approach were discussed on the basis of comparison with the energy width of several multiplets. Overall uncertainties for temperature calculation were evaluated by taking into account the accuracy of Einstein's coefficients and errors of the proposed multiplets method. The temporal evolution of laser plasma during the evaporation of these materials was studied. Extremely high value of the Li I excitation temperature has been estimated to be T > 10⁵ K for the annealed ferrite ablation, in contrast to the temperature T  1.5 · 10⁴ K for non-annealed ferrite. Only for ablation of annealed ferrite the Li II emission line at 548.4 nm was observed. It means that this laser-induced plasma was the hottest. In the case of alloys, the temperature calculated by using Li I transitions was proportional to the microhardness of the solid samples. The negative correlation between crater volume/opto-acoustic signal and alloy microhardness was observed. At the first pulses the mechanical properties of the alloys didn't correlate with the ablated mass, while the maximal correlation coefficients were observed after ablation by 10 or 50 consequent laser pulses.