Comparison of high surface Pt/C catalysts by cyclic voltammetry

Triggered by the resounding success of cisplatin, the past decades have seen tremendous efforts to produce clinically beneficial analogues. The recent achievement of oxaliplatin for the treatment of colon cancer should, however, not belie the imbalance between a plethora of investigated complexes and a very small number of clinically approved platinum drugs. Strategies opening up new avenues are increasingly being sought using complexes of metals other than platinum such as ruthenium or gallium. Based on the chemical differences between these metals, the spectrum of molecular mechanisms of action and potential indications can be broadened substantially. Other approaches focus on complexes with tumour-targeting properties, thereby maximizing the impact on cancer cells and minimizing the problem of adverse side effects, and complexes with biologically active ligands.

Antitumour metal compounds: more than theme and variations

Oxidative stress contributes to the pathophysiology of exposure to heavy metals/metalloid. Beneficial renal effects of some medications, such as chelation therapy depend at least partially on the ability to alleviate oxidative stress. The administration of various natural or synthetic antioxidants has been shown to be of benefit in the prevention and attenuation of metal induced biochemical alterations. These include vitamins, N-acetylcysteine, α-lipoic acid, melatonin, dietary flavonoids and many others. Human studies are limited in this regard. Under certain conditions, surprisingly, the antioxidant supplements may exhibit pro-oxidant properties and even worsen metal induced toxic damage. To date, the evidence is insufficient to recommend antioxidant supplements in subject with exposure to metals. Prospective, controlled clinical trials on safety and effectiveness of different therapeutic antioxidant strategies either individually or in combination with chelating agent are indispensable. The present review focuses on structural, chemical and biological aspects of antioxidants particularly related to their chelating properties.

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Structural, chemical and biological aspects of antioxidants for strategies against metal and metalloid exposure.

Details of the occurrence of the platinum group metals (PGM) in the Earth's crust and the composition of the principal minerals are presented along with data on supply and demand of PGM in different fields. Trace level determination of the PGM requires preconcentration. Methods such as fire assay, chlorination, ion exchange, etc., are dealt with. Analytical techniques used for the determination of PGM such as spectrophotometry, atomic absorption, neutron activation methods, inductively coupled plasma atomic emission and inductively coupled plasma mass spectrometry (ICPMS) are discussed. The ICPMS technique, which has a leading role because of its high sensitivity, simultaneous multi-element capability and a fair degree of tolerance to interferences, is discussed in detail. The need for availability and use of certified reference materials of similar matrix and appropriate PGM content in obtaining reliable data is also discussed.

Platinum group metals (PGM); occurrence, use and recent trends in their determination

Flavonoids are widely occurring polyphenol compounds of plant origin with multiple biological and chemical activities. Due to the presence of carbonyl and hydroxyl groups they can coordinate metal ions and form complexes. Metal complexes of flavonoids have many interesting properties: they are colored, often fluorescent, anti- or pro-oxidant, antimicrobial, antiproliferative and biologically active in many other ways. There are many papers covering specific aspects of activity of flavonoid metal complexes, e.g. their antioxidant properties, enzyme-mimicking behavior, therapeutic potential or use in chemical analysis. However, for a researcher interested in this theme, it would be useful to find an extensive review on more than one selected area. Our aim was to cover a wide spectrum of possible activities and potential applications of flavonoids coordinated to metal ions in order to give our readers a broad view on the topic of this class of compounds, their activity and potential applications. While a significant amount of information on the chemical properties and biological activity of flavonoid metal complexes can be found in the literature, an in-depth understanding of structure–property relationships is still lacking. In an attempt to address this issue, a comprehensive discussion of the available data is presented.

Properties and applications of flavonoid metal complexes

Separation, preconcentration, and spectrophotometry in inorganic analysis

Recent advances in digestion methods used in the analysis of precious metal samples by spectrometric techniques are reviewed. The applicability of a fire assay, a wet acid treatment, chlorination and alkaline oxidizing fusion to a quantitative recovery of metals from various materials is discussed. Data on the precious metal contents obtained by using particular digestion methods as well as UV-VIS spectrophotometry, atomic absorption spectrometry, atomic emission spectrometry and inductively coupled plasma mass spectrometry in the examination of various samples are tabulated.

Maria Balcerzak

Papers

Separation, preconcentration, and spectrophotometry in inorganic analysis

Sample digestion methods for the determination of traces of precious metals by spectrometric techniques.

Determination of chromium, cadmium and lead in food-packaging materials by axial inductively coupled plasma time-of-flight mass spectrometry

Analytical Methods for the Determination of Ruthenium: The State of the Art

Determination of platinum and ruthenium in Pt and Pt–Ru catalysts with carbon support by direct and derivative spectrophotometry