Tellurium(IV) in drinking water

Tellurium is one of the elements recently identified as technologically critical for photovoltaic conversion, quantum dots, as well as in thermoelectric technology, and has the potential to become a new emergent contaminant. Until now there is no guideline value in the World Health Organization’s «Guidelines for Drinking-water Quality» and in the European Drinking Water Directive for tellurium(IV) concentration in drinking water.

To monitor the tellurium(IV) levels in drinking water, anodic stripping voltammetry (ASV) performed on the unmodified scTRACE Gold is recommended. This method allows determination of tellurium(IV) in the concentration range between 1 μg/L and 60 μg/L when using a 90 s deposition time.

The advantage of this method lies in the innovative and cost-effective sensor used for this application: the scTRACE Gold. It is a combined sensor containing the working, reference, and auxiliary electrode integrated on a single ceramic substrate. The scTRACE Gold electrode does not need extensive maintenance such as mechanical polishing. Measurements can be performed in the laboratory with the 884 Professional VA or alternatively in the field with the 946 Portable VA Analyzer.

Drinking water, mineral water

Figure 1. 946 Portable VA Analyzer (scTRACE Gold)

The scTRACE Gold is electrochemically activated prior to the first determination. In the next step, the water sample and the supporting electrolyte are pipetted into the measuring vessel. The determination of tellurium(IV) is carried out with the 884 Professional VA or with the 946 Portable VA Analyzer using the parameters specified in Table 1. The concentration is determined by two additions of a tellurium(IV) standard addition solution.

Figure 2. 884 Professional VA, semiautomated for VA analysis

**Table 1.** Parameters
Parameter	Setting
Mode	DP – Differential Pulse
Deposition potential	-0.3 V
Deposition time	90 s
Start potential	0.1 V
End potential	0.8 V
Peak potential Te	0.475 V

scTRACE Gold

At a 90 s deposition time, this method is suitable for the determination of tellurium(IV) in water samples in concentrations of β(Te(IV)) = 1–30 μg/L using the 884 Professional VA and β(Te(IV)) = 2–75 μg/L using the 946 Portable VA Analyzer.

Figure 3. Determination of Te(IV) in mineral water spiked with 10 μg/L (946 Portable VA Analyzer; 90 s deposition time)

**Table 2.** Results of Te measured in a spiked mineral water sample
Sample	Te(IV) (μg/L)
Mineral water spiked with 10 μg/L	11.5

Contact

Metrohm AG

Ionenstrasse
9100 Herisau

Contact

Internal references: AW VA CH4-0600-082020, AW VA CH4-0602-092020