Rigorous pH measurement in non-aqueous solution: measurement method and reference values in ethanol.

The recently introduced unified pH ([Formula: see text]) concept enables rigorous pH measurements in non-aqueous and mixed media while at the same time maintaining comparability to the conventional aqueous pH scale. However, its practical application is hindered by a shortage of reference [Formula: see text] values. In order to improve this situation, the European Metrology Research Project (EMPIR) UnipHied ("Realisation of a UnipHied pH scale") launched an interlaboratory comparison among highly experienced electrochemistry expert laboratories to assign the first such reference [Formula: see text] values by adopting an extensive statistical treatment of the reported measurement data: to phosphate buffer in water-ethanol mixture (50 wt% of ethanol) and ammonium formate buffer in pure ethanol.

Evaluation and validation of detailed and simplified models of the uncertainty of unified [Formula: see text] measurements in aqueous solutions.

The use of the unified pH concept, [Formula: see text] , applicable to aqueous and non-aqueous solutions, which allows interpreting and comparison of the acidity of different types of solutions, requires reliable and objective determination. The [Formula: see text] can be determined by a single differential potentiometry measurement referenced to an aqueous reference buffer or by a ladder of differential potentiometric measurements that allows minimisation of inconsistencies of various determinations. This work describes and assesses bottom-up evaluations of the uncertainty of these measurements, where uncertainty components are combined by the Monte Carlo Method (MCM) or Taylor Series Approximation (TSM).

Seawater pH measurements with a combination glass electrode and high ionic strength TRIS-TRIS HCl reference buffers - An uncertainty evaluation approach.

The comparison of pH measurements in seawater collected at different locations or occasions, is meaningful if the same measurand (i.e. the quantity intended to be measured) is determined, if adequate measurement procedures are used, including the selection of calibrators, and if the measurement uncertainty is known.

Insights of Pb isotopic signature into the historical evolution and sources of Pb contamination in a sediment core of the southwestern Iberian Atlantic shelf.

Stable Pb isotopic ratios and concentrations of Al, Cu and Pb were measured in a 5m long sediment core (VC2B) retrieved at 96m water depth in the southwestern Iberian Atlantic shelf. Five phases during the last 9.5kyrs were identified, two of them (Roman Period and modern mining) marked by a decrease of Pb/Pb ratios reflecting additional inputs of Pb derived from mining activities.

Footprint of roman and modern mining activities in a sediment core from the southwestern Iberian Atlantic shelf.

A 5-m long sediment core (VC2B), retrieved in the Southwestern Iberian Atlantic shelf, at 96m water depth, was used to assess major changes in climate and human activities during the last 9.7kyrs. Analytical measurements included sedimentological (mean grain size, and the contents of sand, silt and clay), geochemical (major, minor, trace and rare earth elements; REEs) and chronological ((210)Pb and (14)C) parameters.