Iron in water

Iron Fe analyzer

Iron is ubiquitous on the Earth’s crust and can be found in varying amounts in surface waters. It can also be found in drinking water, especially when used as a coagulant in water purification processes.
The determination range of the iron analyzer varies from trace μg/L to 200 mg/L using the (optional) internal dilution module. The range also depends on the chemical method used.

The 3S colorimeter is a compact analytical instrument for online analysis and process monitoring. The colorimeter is based on a color developing chemical reaction that is carried out in the glass measuring cell of the analyzer. The sample, coming from an external reservoir or process stream, is autonomously picked up by the instrument and mixed with the appropriate reagents to allow the reaction to occur. The analyzer uses an LED light source and a photodiode to photometrically measure the developed color intensity (absorption). The absorption is proportional to the concentration of the chemical component to be measured. The detection limit is in the low ppb range.

In an acid-buffered solution, ferrozine and iron react to form a purple-colored complex, measured at 572 nm. The absorption intensity is proportional to the iron concentration in the sample.

As an alternative:

In a slightly acidic buffered solution, 1,10-phenanthroline and ferrous ions react to form an orange color in proportion to the iron concentration. The Fe(II)-phenanthroline complex is quite stable and measured at 430 nm. The absorption intensity is proportional to the iron concentration in the sample. To measure both types of iron, a reduction from Iron(III) to Iron(II) must first be carried out. This method is particularly suitable for the higher measuring ranges, ppm range.