Search results for "S speciation"
showing 4 items of 4 documents
Revision of the Afrotropical genus Leiodontocercus (Orthoptera, Tettigoniidae, Phaneropterinae) with a description of four new species
2020
Specimens belonging to the genus Leiodontocercus are rare or even absent in natural history museum collections; this is likely due to at least two reasons, notably, their relatively small size, and, the sheer difficulty in finding them in dense Afrotropical forests. Until recently, three species from less than fifteen specimens were known from this genus, whose identification relied on a singular diagnostic character, that is, the shape of the male cerci. The present contribution is based on the examination of thirty specimens collected from various countries, ranging from central to west Africa; apart from the male cerci, a second diagnostic character – the stridulatory file – is used to d…
Recent Approaches for Chemical Speciation and Analysis by Electrospray Ionization (ESI) Mass Spectrometry
2021
In these latest years, the chemical speciation of several species has been increasingly monitored and investigated by means of electrospray ionization mass spectrometry (ES-MS). This soft ionization technique is capable to gently take into the gas phase metal-ligand complexes and gather a wealth of information on their energetics, shape, and fragmentation pathways. For this reason, this technique is frequently chosen in a synergistic approach to investigate competitive ligand exchange-adsorptive other ways analyzed by cathodic stripping voltammetry (CLE-ACSV). ESI-MS analyses require a careful experimental design as they may be impacted by instrumental artifacts such as ESI adduct formation…
A Raman calibration for the quantification of SO42-groups dissolved in silicate glasses: Application to natural melt inclusions
2017
Sulfur is an important volatile element involved in magmatic systems. Its quantification in silicate glasses relies on state-of-the-art techniques such as electronprobe microanalyses (EPMA) or X-ray absorption spectroscopy but is often complicated by the fact that S dissolved in silicate glasses can adopt several oxidation states (S6+for sulfates or S2-for sulfides). In the present work, we use micro-Raman spectroscopy on a series of silicate glasses to quantify the S content. The database is constituted by 47 silicate glasses of various compositions (natural and synthetic) with S content ranging from 1179 to 13 180 ppm. Most of the investigated glasses have been synthesized at high pressur…
Speciation of organic matter in natural waters. Interaction of polyacrylates with the major cation components of seawater
2004
The speciation of some high molecular weight polycarboxylates was studied in different ionic media. Polyacrylates here investigated (W=2.0, 5.1 and 20.0 kDa) form weak species with alkali metal cations (K=102 mol l1, t=25 jC, I=0 mol l1) and quite stable complexes with alkaline earth metal cations (K>106 mol l1, t=25 jC, I=0 mol l1). Results are reported from experiments performed in a multicomponent electrolyte solution simulating the major composition of seawater (artificial seawater). Protonation constants in this medium are expressed as a polynomial function of S1/2 (S=salinity) and the sharp lowering with respect to values obtained in non-interacting aqueous tetraalkylammonium salts ca…