A. A. Gorbatenko

Reduction of the matrix influence on analytical signal in laser-enhanced ionization spectrometry with laser sampling

The novel approach using a slope of correlation line (laser-enhanced ionization of lithium versus laser-induced plasma emission of aluminum) as analytical signal was proposed for reduction of matrix interferences in laser-enhanced ionization spectrometric determination of Li with laser sampling.

A review of instrumental methods for determination of rare earth elements

Modern instrumental methods for determination of rare earth elements most successfully used in analytical practice are considered. The analytical characteristics and the figures of merit of various analysis techniques are compared, among which atomic emission spectrometry, inductively coupled plasma mass spectrometry (ICP-MS), and neutron activation analysis (NAA) occupy a special place.

Analysis of Slightly Volatile Samples by Atomic-Ionization Spectrometry with Laser Ablation into Flame

The potentialities of laser-enhanced atomic-ionization spectrometry with laser ablation for the analysis of slightly volatile and difficultly ionized samples were studied using lithium polyvanadate as an example. The effect of the cathode voltage and the power of the ablation beam on the signal in the analysis of such samples was studied. The optimum measurement range was determined as a function of the number of subsequent ablation pulses acting upon the same surface point. This minimized the effect of the surface contaminants and the change in ablation conditions as the crater deepened.

Signal Formation in Laser-Enhanced Atomic Ionization Spectrometry with Laser Sampling into the Flame

The results of the observation of ionization signals in the laser-ablation sampling of solid samples into the flame were reported. The signals exhibited two maxima. The first, nonselective, maximum, which appeared immediately after the pulse of the volatilization laser, is due to thermions formed in the laser plasma. The second, selective (analytical), signal appeared after the pulse of the optical excitation laser. The nonselective signal may interfere with the detection of the analytical signal. The dependence of both signals on parameters such as the height of the cathode and the height of signal observation above the burner and the time delay between the laser pulses was studied. The optimal conditions for the detection of signals in laser-enhanced atomic ionization spectrometry were found.

Determination of refractory elements by laser‐induced ionization spectrometry of molecular species in seeded flames

For the most refractory elements the detection limits in laser‐induced ionization (LII) atomic spectrometry in conventional analytical flames are not so low because these elements produce stable metal oxides. There are two possible ways to overcome this problem: to use LII atomic spectrometry in high‐temperature flames or to use LII molecular spectrometry in cooler flames. In this report we describe our initial results applying LII spectrometry of LaO molecules in natural gas/air flame to La determination in aqueous solution. Without having optimum condition detection limit of 10 ng/mL La was reached.

Laser microbe sampling and laser‐enhanced ionization spectrometry in flames for surface analysis

Laser microprobe was used for direct introduction of solid samples into a flame. Combination of this technique with laser‐enhanced ionization spectrometry provides highly sensitive method for surface analysis of Al samples. The impurities of Li were measured. The spatial distribution of Li in laser plume was not homogeneous: the dense atomic ‘‘nucleus’’ and the ‘‘tail’’ of Li clusters. The surface resolution was better than 100 microns. This technique allows to perform surface and layer‐by‐layer analysis of solids and thin films.

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.

Optimizing the Conditions of the Experiment in Atomic Ionization Spectrometry with Laser-Induced Evaporation of Material into a Flame

Two ionization signals — selective and nonselective — are recorded on laser-induced evaporation of solid samples into a flame with subsequent exposure to resonance radiation. The magnitudes of the signals depend on many experimental parameters: the composition of the sample, the composition of the environment and gas mixture, etc. The dependences of the nonselective and selective signals on such experimental parameters as the voltage on the cathode and the energy of the vaporizing radiation have been studied. The optimum energy of the vaporizing radiation was 44–48 mJ at the cathode voltage 500–800 V. This has allowed the coefficient of correlation of the calibration graph to be raised up to 0.99. In these conditions, the limit of detection of Li was 0.017%.

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.

Laser-Enhanced Molecular-Ionization Spectrometry of BaO and LuO in Low-Temperature Flame

The molecular ionization spectra of BaO and LuO were recorded in low-temperature natural gas-air flame with excitation laser wavelengths in the range 440–480 and 535–575 nm. Addition excitation of barium and lutetium monoxides by a second laser quantum did not amplify the ionization signal. One-step laser excitation with wavelengths of 549.3 and 466.2 nm is optimal for BaO and LuO, respectively.