Wednesday, February 17, 2010

Voltammetric Device Measures Labile Copper Content

The Metrohm 797 VA Computrace can be used for the determination of labile copper in sea water. Spectroscopic methods can only determine the total concentrations of metals, but with voltammetry it is possible to differentiate between the different oxidation states of copper. This allows statements to be made about the biological availability and toxicity, making voltammetry an essential tool in environmental analysis.

Copper is one of the most toxic-heavy metals known to marine life, generally concentrations of heavy metals are comparatively low in open sea areas where human activities have not yet had a major detrimental effect. However, in coastal area, contamination is usually more widespread often in offshore sediments close to municipal and industrial discharge points. Many marine and research institutions are interested in determining the relationship between the labile (or free copper) and total copper, both of which can easily and reliably be performed using the 797 VA Computrace from Metrohm.

The 797 VA Computrace is a modern voltammetric measuring instrument that connects to a PC via a USB connection. The Windows XP-based PC software controls the measurement, records the measuring data and allows full evaluation of the recorded information. The sample and auxiliary solutions are added to the reaction vessel and the labile copper is determined on a mercury film formed at the surface of the ultra-trace electrode. By performing the analysis first using an ultra-trace electrode then separately using a classic mercury electrode, it is possible to measure first the values of labile and then total copper to determine the ratio of the different species.

Whether the labile or total copper is being determined, the process can be partially or fully automated through the use of Metrohm Dosino dispensing devices and autosamplers. The low running costs are an additional bonus point for voltammetry requiring no expensive combustible gases or reconstruction of the laboratory infra-structure to accommodate specialist ducting and fume hoods. Apart from the small amounts of reagents required for the analysis, only small volumes of pure nitrogen are required.

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