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Iron is an essential element in human nutrition. It can be present in drinking water as a result of water treatment or from corrosion in the water piping system. There is no guideline value for iron in the World Health Organization’s «Guidelines for Drinking-water Quality» because typical levels usually found in drinking water are of no concern. However, there are national limit values in various countries. The European Union has set a guideline indicator value for iron of 200 μg/L.

Voltammetry is a viable, less sophisticated alternative to atomic absorption spectroscopy (AAS) for the determination of iron in drinking water. While AAS (and competing methods) can only be performed in a laboratory, anodic stripping voltammetric determinations can be done used conventionally in the laboratory or alternatively in the field using the with 946 Portable VA Analyzer. The determination is carried out with adsorptive stripping voltammetry (AdSV) using 2,3-dihydroxynaphthalene (DHN) on the scTRACE Gold electrode.

Tap water

946 Portable VA Analyzer (scTRACE Gold version)
Figure 1. 946 Portable VA Analyzer (scTRACE Gold version)

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 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 standard addition solution.

Figure 2. 884 Professional VA fully automated for VA
Table 1. Parameters
Parameter Setting
Mode DP – Differential Pulse
Deposition potential 0 V
Deposition time 30 s
Start potential -0.3 V
End potential -0.95 V
Peak potential Fe -0.65 V
  • scTRACE Gold

The limit of detection of the method is about 10 μg/L with the 946 Portable VA Analyzer, and approximately 0.3 μg/L with the 884 Professional VA.

Figure 3. Determination of iron in tap water (946 Portable VA Analyzer; 30 s deposition time)
Table 2. Results for the measurement of Fe in spiked tap water
Sample Fe, blank subtracted (μg/L)
Tap water (spiked) 10

Metrohm AG

9100 Herisau


Internal references: AW VA CH4-0578-032019; AW VA CH4-0582-042019