Arsenic: occurrence, toxicity and speciation techniques

Global ammonia production reached 175 million metric tons in 2016, 90% of which is produced from high purity N2 and H2 gases at high temperatures and pressures via the Haber-Bosch process. Reliance on natural gas for H2 production results in large energy consumption and CO2 emissions. Concerns of human-induced climate change are spurring an international scientific effort to explore new approaches to ammonia production and reduce its carbon footprint. Electrocatalytic N2 reduction to ammonia is an attractive alternative that can potentially enable ammonia synthesis under milder conditions in small-scale, distributed, and on-site electrolysis cells powered by renewable electricity generated from solar or wind sources. This review provides a comprehensive account of theoretical and experimental studies on electrochemical nitrogen fixation with a focus on the low selectivity for reduction of N2 to ammonia versus protons to H2. A detailed introduction to ammonia detection methods and the execution of control experiments is given as they are crucial to the accurate reporting of experimental findings. The main part of this review focuses on theoretical and experimental progress that has been achieved under a range of conditions. Finally, comments on current challenges and potential opportunities in this field are provided.

Recent Advances and Challenges of Electrocatalytic N2 Reduction to Ammonia.

The contribution of zinc ions to the antimicrobial activity of zinc oxide

Ionic substances with melting points at or close to room temperature are referred to as ionic liquids. Interest in ionic liquids for their potential in different chemical processes is increasing, because they are environmentally benign and are good solvents for a wide range of both organic and inorganic materials. In this study, a capillary electrophoretic method for resolving phenolic compounds found in grape seed extracts is reported. The method, in which 1-alkyl-3-methylimidazolium-based ionic liquids are used as the running electrolytes, is simple and reproducible. The separation mechanism seems to involve association between the imidazolium cations and the polyphenols. The role of the alkyl substituents on the imidazolium cations was investigated and will be discussed.

Capillary electrophoretic application of 1-alkyl-3-methylimidazolium-based ionic liquids.

Determination of 13 synthetic food colorants in water-soluble foods by reversed-phase high-performance liquid chromatography coupled with diode-array detector.

Determination of eight synthetic food colorants in drinks by high-performance ion chromatography.

Parameters influencing separation and detection of anions by capillary electrophoresis

The development and evaluation of a new method for the determination of trace transition and rare-earth elements based on the combination of chelation and ion chromatography are described. The new method, chelation ion chromatography (Chelation IC), uses a chelating column to concentrate and separate transition and rare-earth elements from the common alkali and alkaline-earth metals, as well as other matrix components, prior to analysis by ion chromatography. The sample fraction from the chelating column contains only the concentrated analyte ions, thus eliminating interfering matrix components from complex matrices such as seawater and digested biological, botanical, and geological materials. This combination of chelation and ion chromatography provides a technique that makes possible the determination of trace elements in complex matrices that have proven to be difficult or impossible to analyze by ion chromatography or conventional atomic spectroscopy techniques.

John M. Riviello

Papers

Determination of eight synthetic food colorants in drinks by high-performance ion chromatography.

Parameters influencing separation and detection of anions by capillary electrophoresis

Chelation ion chromatography as a method for trace elemental analysis in complex environmental and biological samples.

New strategies for determination of transition metals by complexation ion-exchange chromatography and post column reaction

A new approach to dealing with high-to-low concentration ratios of sodium and ammonium ions in ion chromatography