Liquid chromatography-inductively coupled plasma mass spectrometry

It is known that while many elements are considered essential to human health, many others can be toxic. However, because the intake, accumulation, transport, storage and interaction of these different metals and metalloids in nature is strongly influenced by their specific elemental form, complete characterization of the element is essential when assessing its benefits and/or risk. Consequently, interest has grown rapidly in determining oxidation state, chemical ligand association, and complex forms of a many different elements. Elemental speciation, or the analyses that lead to determining the distribution of an element’s particular chemical species in a sample, typically involves the coupling of a separation technique and an element specific detector. A large number of methods have been developed which utilize a multitude of different separation mechanisms and detection instruments. Yet, because of its versatility, robustness, sensitivity and multi-elemental capabilities, the coupling of liquid chromatography to inductively coupled plasma mass spectrometry (LC–ICP–MS) has become one of the most popular techniques for elemental speciation studies. This review focuses on the basic principles of LC–ICP–MS, its historical development and the many ways in which this technique can be applied. Different liquid chromatography separations are discussed as well as the factors that must be considered when coupling each to ICP–MS. Recent applications of LC–ICP–MS to the speciation of environmental, biological and clinical samples are also presented.     

Mass spectral characterization of polymers. Primary thermal fragmentation processes in polyureas

The primary fragmentation processes in the thermal decomposition of polymers were studied in detail on a series of structurally related polyureas by direct pyrolysis with a mass spectrometer. Our results indicate that polyureas I–III undergo a quantitative depolycondensation process analogous to that observed for N-monosubstituted polyurethanes. The thermal decomposition of polyureas IV–VI proceeds by intramolecular hydrogen transfer processes that occur at higher temperatures with respect to depolycondensation. Polycarboxypiperazine VI is decomposed by a single-stage decomposition mechanism that leads to fragments with amino end groups and carbon oxide.     

Regioselective Alkylation of Lithium Enolates Derived from 2-Heptanone

The benzylation and $\text{u}$-butylation of the kinetic enolate mixture derived from 2-heptanone has been studied in DME in the absence and in the presence of lithium ion complexing agents (triglyme, benzo-14-crown-4, DMF (neat), DMF, and HMPA).     

Preliminary studies on selenium-containing proteins in Brassica juncea by size exclusion chromatography and fast protein liquid chromatography coupled to ICP-MS

An approach for screening and resolving selenium-containing plant proteins was developed based on the combination of sample preparation and multi-dimensional liquid chromatography coupled to ICP-MS. Different protein extraction protocols were investigated. A 24 h dodecylsulfate-mediated protein extraction in a sonication bath followed by acetone precipitation was found to be optimal. The use of different protein precipitate solubilizing agents (sodium dodecyl sulfate media and Tris-HCl buffer) demonstrates possible fractionation of the selenium-containing proteins. Selenium-containing protein screening and fractionation were carried out by means of SEC-ICP-MS. High molecular weight selenium containing proteins were solubilized with a sodium dodecyl sulfate-containing buffer, whereas the low molecular weight compounds were released into a Tris-HCl buffer. Size exclusion chromatography-fast protein liquid chromatography coupled to ICP-MS allowed separation and detection of several selenium-containing proteins in Se-supplemented wild type Brassica juncea plant, a fast growing selenium accumulator.     

Augusto Sirigu (1939–2007)

Two series of novel symmetrical azomethines prepared by the condensation of 4,4′-(butane-1,4-diylbis(oxy))bis(butane-4,1-diyl)bis(4-aminobenzoate) (PBBA470) and 5,10,15,20,25,30,35,40,45,50,55,60-dodecaoxatetrahexacontane-1,64-diylbis(4-aminobenzoate) (PBBA 1200) with a range of aldehydes have been characterised by ¹H and ¹³C nuclear magnetic resonance, Fourier transform infrared and UV–Vis spectroscopy. Current–voltage measurements were performed using a device comprising indium–tin oxide/compound/Alq₃/Al. The effect of rod length and the nature of the terminal chains on the thermal and mesomorphic behaviour of these materials were investigated by differential scanning calorimetry, polarising optical microscopy and wide- and small-angle X-ray diffraction. Additionally, the compounds were studied using various atomic force microscopy techniques, including mode and phase imaging, and measurements based on local contrast force–distance curves and roughness, together with skew and kurtosis, are presented.