There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Microwave assisted organic synthesis-a review

Bioorganometallic Chemistry of Ferrocene

Solid phase extraction of trace elements

It is important to evaluate different digestion methods to accurately determine elemental concentrations in soils. Three commonly used digestion procedures, hotplate aqua regia, microwave aqua regia, and microwave aqua regia + HF, were compared for digestion of three standard reference materials (SRMs 2704, 2709, and 2711) and 20 Florida soils (three groups of Quartzipsammemts, one group of Alaquods, and one group of Paleudults). Sixteen elements (Al, Ba, Ca, Fe, K, Mg, Mn, P, Zn, As, Cd, Cr, Cu, Ni, Pb, and Se) were analyzed using either an inductively coupled plasma optical emission spectrometer (ICP-OES) or a graphite furnace atomic absorption spectrophotometer (GFAAS). Precise analysis was achieved for all elements except As (1.0-25%), Cd (1.8-22%), and Se (4.1-22%) in the SRMs using all three procedures, with the microwave aqua regia + HF procedure having slightly better precision (3.7%) averaged across all elements. Compared with the elemental recoveries in SRMs by the microwave aqua regia digestion (80%), microwave aqua regia + HF digestion achieved greater accuracy (94%), whereas the hotplate aqua regia digestion achieved less accuracy (74%). In general, the microwave aqua regia + HF digestion was overall the best procedure for determining concentrations of most metals in SRMs and Florida soils, followed by the microwave aqua regia and the hotplate aqua regia digestion. However, this so-called total-total digestion procedure (microwave aqua regia + HF) may underestimate total Pb concentration in Florida soils and total Al, Ca, Fe, Mg, and Ba concentrations in the Florida Paleudults.

Comparison of Three Aqua Regia Digestion Methods for Twenty Florida Soils

This paper presents the results of the mineralogical, petrographic, elemental, and isotopic analysis of the Chelyabinsk meteorite and their geochemical interpretation. It was shown that the meteorite can be assigned to LL5-group ordinary chondrites and underwent moderate shock metamorphism (stage S4). The Chelyabinsk meteorite contains a significant fraction (approximately one-third by volume) of shock-melted material similar in composition to the main volume of the meteorite. The results of isotopic analysis suggest that the history of meteorite formation included an impact event approximately 290 Ma ago.

Analytical Results for the Material of the Chelyabinsk Meteorite

Nowadays much attention is being paid to the determination of trace amounts of noble metals in geological, industrial, biological and environmental samples. The most promising techniques, such as inductively coupled plasma atomic emission spectrometry (ICP-AES), inductively coupled plasma mass spectrometry (ICP-MS) and electrothermal atomic absorption spectrometry (ETAAS) are characterized by high sensitivity. However, the accurate determination of trace noble metals has been limited by numerous interferences generated from the presence of matrix elements. To decrease, or eliminate, these interferences, the sorption preconcentration of noble metals is often used prior to their instrumental detection. A great number of hyphenated methods of noble metal determination using sorption preconcentration have been developed. This review describes the basic types of available sorbents, preconcentration procedures and preparations of the sorbent to the subsequent determination of noble metals. The specific features of instrumental techniques and examples of ETAAS, FAAS, ICP-AES, ICP-MS determinations after the sorption preconcentration of noble metals are considered. The references cited here were selected mostly from the period 1996 - 2006.

/pdf/trends-in-sorption-preconcentration-combined-with-noble-2hvdrt8f80.pdf

Trends in Sorption Preconcentration Combined with Noble Metal Determination

A rapid and sensitive method for the differential determination of CrIII and CrVI in river water is described. Chromium species can be separated by sorption on a polymeric Detata sorbent containing conformationally flexible aminocarboxylic groups. Preconcentration using either static or dynamic conditions is possible. Microwave heating energy was used to promote the sorption. Quantitative sorption of CrIII was achieved at pH 7, and that of CrVI at pH 3; hence, complete isolation of the two forms of Cr is possible. The optimum conditions (flow rate and sorbent volume) for sorbent extraction of CrIII and CrVI were evaluated. The technique developed is based on the ability of the sorbent to preconcentrate Cr rapidly under dynamic conditions in the presence of a microwave field. Determination of Cr by electrothermal atomic absorption spectrometry is possible either after desorption or directly in the sorbent phase. The detection limit (based on the 3s criterion) is 30 ng l–1; the technique is characterized by high reproducibility.

Determination of chromium(III) and chromium(VI) in river water by electrothermal atomic absorption spectrometry after sorption preconcentration in a microwave field

Chemical Attachment of Organometallics to Proteins in Reverse Micelles

The key aspects of the effect of microwaves on the physicochemical processes in solutions and heterogeneous systems are analysed. Good prospects for the use of microwave radiation for intensifying various types of interaction are demonstrated in relation to dissolution, hydrolysis of organic and inorganic substances, complex formation by metal ions in solution and in the sorbent phase, oxidation of organic compounds, and synthesis of coordination and organic compounds. Specific features of analytical operations with microwave treatment are considered and the trends of development of analytical methods using microwaves are discussed. The bibliography includes 137 references.

https://iopscience.iop.org/article/10.1070/RC2002v071n04ABEH000699/pdf

Irina V. Kubrakova

Papers

Analytical Results for the Material of the Chelyabinsk Meteorite

Trends in Sorption Preconcentration Combined with Noble Metal Determination

Determination of chromium(III) and chromium(VI) in river water by electrothermal atomic absorption spectrometry after sorption preconcentration in a microwave field

Chemical Attachment of Organometallics to Proteins in Reverse Micelles

Microwave radiation in analytical chemistry: the scope and prospects for application