“At present, around 130 million different substances are known—and the number is growing,” explained Dr. André Liesener, Westfälische Wasser- und Umweltanalytik GmbH (WWU). Target analysis helps detecting these substances in water and determining them quantitatively with great accuracy.
However, the prerequisite is that they are specifically searched for because they are suspected in a sample. And target analytics quickly reaches its limits when the water contains a whole cocktail of substances of which only a fraction is known.
This is where new screening methods are come in that are only five or six years old, as André Liesener emphasized. Both Non-Target Screening (NTS) and Suspect Target Screening (STS) are designed to detect as many substances as possible and to provide qualitative evidence. These techniques—with certain limitations—can also be used to demonstrate the absence of a substance. The information obtained can then be used to develop targeted methods for the quantitative determination of substances that are relevant. “Our laboratory capacities can thus be used much more efficiently,” said Liesener.
On behalf of Gelsenwasser AG, the chemist regularly examines the water in the Haltern waterworks south of Münster. Around 200 substances, including 120 plant protection agents, are continuously monitored here using target analytics. If the pollutant concentrations are above the limit values, the substances in question are removed from the water with the aid of activated carbon. To save costs, however, the addition of the expensive activated carbon is dependent on the concentration values determined. However, this sophisticated monitoring concept is not capable of recording all substances occurring in the waterworks. In addition, WWU has therefore relied on NTS and STS results for some time. According to Liesener, these techniques have in fact made it possible to detect a substance (terbotlyazine) that had previously not been considered. The substance is used as a plant protection agent, but is also the degradation product of other chemical compounds that are released into the water, for example through pharmaceuticals via the end user. The consequently used target analysis finally provided quantitative proof of the substance. In the future, this substance can therefore be controlled more closely.
Organizer: German Technical and Scientific Association for Gas and Water (DVGW)