Going Green: Mercury-free determination of heavy metals by voltammetric trace analysis

Stripping voltammetry uses electrochemical sensors for the determination of heavy metal ions in different types of samples. To meet legal regulations and eliminate the use of metallic mercury, Metrohm has developed Hg-free sensors. These Hg-free sensors can measure trace levels of cadmium, lead, zinc, arsenic, chromium, and other heavy metals in various water matrices ranging from boiler feed to drinking to sea water samples. Afree White Paperpresents the details of this solution along with several application examples.

Low detection limits (between µg/L and ng/L), the possibility to distinguish between different oxidation states (e.g., As(V) and As(III)) as well as free and bound metal ions, and low costs of ownership combined with quick results (within 10–15 minutes) make stripping voltammetry attractive for both stationary and mobile applications.

Recently, Metrohm has taken great efforts to combat the challenges related to the replacement of toxic Hg in the voltammetric determination of heavy metals. These efforts have resulted in the development of four new mercury-free sensors:

• ScTRACE Gold electrode
• 11L carbon screen printed electrode
• Glassy carbon electrode
• Bismuth drop electrode

By utilising these sensors with the884 Professional VAor the946 Portable VA Analyzerfrom Metrohm, a total amount of 16 heavy metals can be determined with high selectivity and reproducibility of results with detection limits in the µg/L or ng/L range.