Major ion chemistry of the Ganga-Brahmaputra river system: Weathering processes and fluxes to the Bay of Bengal

Major ion chemistry of the Ganges-Brahmaputra river system : weathering processes and fluxes to the Bay of Bengal

This paper demonstrates, for the first time, that ionic liquids (IL) such as 1-octyl-3-methylimidazolium hexafluorophosphate ([C8MIM][PF6]) are excellent extraction solvents in liquid-phase microextraction (LPME). The unique properties of nonvolatility and adequate viscosity allow IL to be conveniently adopted as extraction solvents in both direct-immersion and headspace LPME. Model compounds, polycyclic aromatic hydrocarbons (PAHs), are conveniently and rapidly enriched in a 3-μL drop of [C8MIM][PF6] suspended on the tip of a microsyringe followed by liquid chromatographic determination. Compared to 1-octanol, a larger volume drop of [C8MIM][PF6] can be formed and survive for a longer extraction time; therefore, a much higher enrichment factor for PAHs can be reached. For low-volatility PAHs, direct-immersion LPME provides higher enrichment factors than that of headspace LPME. However, the enrichment factor obtained by headspace LPME was almost 3-fold of that by direct-immersion LPME in a 30-min extracti...

Use of ionic liquids for liquid-phase microextraction of polycyclic aromatic hydrocarbons.

A novel method for the detection of arsenic(III) in 1 M HCl at a gold nanoparticle-modified glassy carbon electrode has been developed. The gold nanoparticles were electrodeposited onto the glassy carbon electrode via a potential step from +1.055 to −0.045 V vs SCE for 15 s from 0.5 M H2SO4 containing 0.1 mM HAuCl4. The resulting electrode surfaces were characterized with both AFM and cyclic voltammetry. Anodic stripping voltammetry of arsenic(III) on the modified electrode was performed. After optimization, a LOD of 0.0096 ppb was obtained with LSV.

Anodic stripping voltammetry of arsenic(III) using gold nanoparticle-modified electrodes.

The speciation of trace elements in waters.

Spectrophotometric determination of chloride at the parts-per-billion level by the mercury(II) thiocyanate method

Cathodic stripping voltammetry: Part I. Determination of organic sulfur compounds, flavins and porphyrins at the sub-micromolar level

A highly sensitive and selective method is described for the spectrophotometric determination of uranium. The chromogenic reagent is 4-(2- pyridylazo)resorcinol (PAR), and the determination is carried out at pH 8.0 in the presence of a mixed complexing solution containing (1,2cyclohexylenedinitrilo)tetraacetic acid, sulfosalicylate, and fluoride. Most metals, including thorium, are masked by the complexing solution. Uranium forms a 1: 1 complex with PAR, which has a molar absorptivity of 38,700 at 530 M mu . A preliminary separation of uranium from gross amounts of impurities may be accomplished by a rapid chelating-resin ion exchange procedure. (auth)

T.M. Florence

Papers

Spectrophotometric determination of chloride at the parts-per-billion level by the mercury(II) thiocyanate method

Cathodic stripping voltammetry: Part I. Determination of organic sulfur compounds, flavins and porphyrins at the sub-micromolar level

Spectrophotometric Determination of Uranium with 4-(2-Pyridylazo)resorcinol.

Determination of thallium in natural waters by anodic stripping voltammetry

Determination of arsenic and antimony in electrolytic copper by anodic stripping voltammetry at a gold film electrode