If we evaporated a liter of water, a thin layer would remain at the bottom white powder: it is the so-called fixed residuecomposed of mineral salts and traces of heavy metals. Precisely the latter – lead, mercury, cadmium and others – are at the center of the chemical analyses which, as you can see from the video, guarantee the safety of the water we drink every day.
The water, before reaching the taps or being bottled, flows between rocks and soil, enriching itself with elements present in the earth’s crust. In addition to the mineral salts useful for our body, it can therefore also contain non-essential metals (they are of no use to our body) such as arsenic, lead, mercury, cadmium and nickel.
These elements, although natural, are toxic even at low concentrations and they tend to bioaccumulate in living organisms. For this reason, it is very very important that water intended for human consumption has a concentration of these elements below a certain level: as long as the quantities remain below the threshold, the water is safe. As always, it’s the dose that makes the poison.
But how do we make sure their concentration is low enough? With chemical analyses. In fact, if we take the label of any bottled water we can notice that there is a lot of data such as: pH, conductivity, fixed residue and then there are a whole series of values that indicate the concentration of sodium, calcium, magnesium, potassium, chlorides, fluorides, carbonates, etc. What about heavy metals?
As can be seen in the video, in the fixed residue (i.e. the total quantity of mineral salts and trace elements dissolved in a liter of water that remains after evaporation of the sample at 180°C) there are also heavy metals, but in such low quantities that they do not cause any type of damage. And to understand if their concentration is below the legal limit, we need instruments that work thanks to incredible technology.
And these tools are provided by specialized companies such as FKVhistoric supplier of scientific instrumentation for laboratory analysis and partner of this video.
All metals are analyzed and quantified with machinery like the one seen in the video, one spectrometer mass inductively coupled plasma, called ICP-MS. Conceptually it is an instrument capable of understanding the concentration of all ions, including those of heavy metals with extreme sensitivity and precision.
The operation of this tool is complex, but the most interesting aspect concerns the plasmaa gas at a very high temperature (around 8000 °C), a temperature even higher than that of the surface of the Sun. Under these conditions, metals lose electrons and become ionscharged particles that can be identified with great precision. In this way the tool provides extremely accurate data on the concentration of both heavy metals both gods beneficial ions such as sodium, calcium and magnesium.
In Italy, fortunately, the waters that flow in our territories are almost free of these metals, so they are there but in such low concentrations that they are not a problem for us.
In addition to the spectrometer, laboratories also use automatic multiparametric titrators, instruments that measure substances such as cyanides, ammonium and fundamental parameters such as color, pH and conductivity. Thanks to these technologies it is possible precisely control the water qualityensuring that the one from the tap or in the bottle is safe to drink.
