Publications by authors named "Dimiter L Tsalev"

Academician Yuri Aleksandrovich Zolotov is a world-wide recognized man in analytical science and chemical analysis. This paper is an appreciation by the author for the long term influence of Professor Zolotov scientific ideas and creative publications on his raising up as scientist during his early studies at Moscow State University and generally on his professional life. The article is a hybrid of personal tribute, historical reminiscence, and a brief tutorial mostly aimed at juniors in science.

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A simple classification of various sorbents and solid-phase extraction procedures used for preconcentration of trace levels of Au, Pd, and Pt from different sample types is proposed in this review article. The large variety of available sorbents/procedures has been organized according to expected mechanisms of sorption process (complex formation; ion exchange; adsorption; ion-imprinted or molecularly imprinted polymers); according to the kind of monomeric units of the polymer matrix as well as on the basis of the kind of functional group responsible for main performance characteristics (selectivity, capacity) of the sorbent. Advantages of chemically modified sorbents, sulfur-containing sorbent extractants, and ion-imprinted polymers, together with rational pretreatment by means of microwave treatments, scaling down of enrichment, and quantification by means of flow and flow injection approaches are given.

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Trace metal speciation in seawater from the Bulgarian Black Sea coast was studied in situ by hollow fiber permeation liquid membrane (HF-PLM) and by diffusion gradients in thin-film gels (DGT). The concentrations of Cd, Cu, Ni, and Pb determined by HF-PLM were lower than those measured by DGT, in agreement with their analytical windows, e.g.

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Analytical procedure for the determination of toxicologically relevant arsenic (the sum of arsenite, arsenate, monomethylarsonate and dimethylarsinate) in urine by flow injection hydride generation and collection of generated inorganic and methylated hydrides on an integrated platform of a transverse-heated graphite atomizer for electrothermal atomic absorption spectrometric determination (ETAAS) is elaborated. Platforms are pre-treated with 2.7 micromol of zirconium and then with 0.

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Validation of reducing-difference procedure based on subtracting of non-polarized infrared (IR) spectra of n-component solid mixtures is presented. The accuracy and precision are established. The limits of detection are 3.

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Analytical procedures for electrothermal atomic absorption spectrometric (ETAAS) determination of arsenic in essential oils from lavender (Lavendula angustifolia) and rose (Rosa damascena) are described. For direct ETAAS analysis, oil samples are diluted with ethanol or i-propanol for lavender and rose oil, respectively. Leveling off responses of four different arsenic species (arsenite, arsenate, monomethylarsonate and dimethylarsinate) is achieved by using a composite chemical modifier: l-cysteine (0.

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An overview of literature data on vapour generation techniques for cadmium and comparison with own experiments by means of several different types of hydride generation-electrothermal atomic absorption spectrometric systems (HG-ETAAS) (batch, semi-batch (SB), continuous-flow (CF) and flow-injection (FI) as well as different gas-liquid separators (GLS) exhibits apparent variations and inconsistency. However, if data for optimal chemical conditions are re-plotted in another coordinates: C(HCl) (mol l(-1)) vs. the ratio of reductant-to-acid molar input rates (i.

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Some drawbacks of the phosphate modifier such as reagent blank contribution and background absorption in electrothermal atomic absorption spectrometric determination of cadmium and lead are substantially alleviated by application of small amounts of phosphate, approximately 0.2 mumol (25 mug of NH(4)H(2)PO(4) or (NH(4))(2)HPO(4)), on the integrated platform of transversely heated graphite atomizer pre-treated with 2.7 mumol of Zr (250 mug) or W (500 mug) and 0.

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The present study focuses on the biouptake, biotransformations, and toxicity of arsenic species on the marine green alga Chlorella salina in seawater from the Bulgarian Black Sea coast. Exposure to equal concentrations of As(III) or As(V) led to equivalent levels of toxicity and total intracellular arsenic content. Biouptake and toxicity of methylated arsenic species, monomethylarsonate (MMA) and dimethylarsinate (DMA), were approximately three orders of magnitude lower than those for inorganic arsenic species.

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Quantitative infrared (IR) and Raman spectroscopic approach for determination of phenacetin (Phen) and salophen (Salo) in binary solid mixtures with caffeine: phenacetin/caffeine (System 1) and salophen/caffeine (System 2) is presented. Absorbance ratios of 746 cm(-1) or 721 cm(-1) peaks (characteristic for each of determined compounds in the Systems 1 and 2) to 1509 cm(-1) and 1616 cm(-1) (attributed to Phen and Salo, respectively) were used. The IR spectroscopy gives confidence of 98.

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A rapid, accurate, and precise method is described for the determination of Pb in wine using continuous-flow hydride generation atomic fluorescence spectrometry (CF-HGAFS). Sample pretreatment consists of ten-fold dilution of wine followed by direct plumbane generation in the presence of 0.1 mol L(-1) HCl and 1% m/v K(3)[Fe(CN)(6)] with 1% m/v NaBH(4) as reducing agent.

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