From lab experiments to environmental safety: EU_NITRA_UKR team conducts practical workshop for lyceum students at NUBIP of Ukraine

On April 2, 2026, the EU_NITRA_UKR project team held a lecture and a hands-on chemical experiment titled “Safe Nitrate-Free Drinking Water: How to Analyse and What We Can Do”. The event took place at the Laboratory of the Department of Analytical and Bioinorganic Chemistry and Water Quality (Agrobiological Faculty) as part of an initiative to engage teachers and graduates from Kyiv lyceums. The session was attended by eight students and two teachers from Kyiv Lyceum No. 241.

 The lecture portion included a presentation of the project’s goals and objectives, highlighting Ukraine’s progress in implementing European standards (the EU Nitrates Directive) to protect the environment, public health, and develop a circular (zero-waste) economy.

  The following topics were discussed:

       1. Problem Statement: What are nitrates and where do they come from?

      Sources of pollution: Agriculture (fertilizers, manure), wastewater, and private wells.

  Pathways to humans: How excess nitrogen enters groundwater and accumulates in early-season vegetables (watermelons, leafy greens, radishes).

      Health impact: Risks for children (methemoglobinemia) and adults.

       2. European Experience: The EU Nitrates Directive

      European actions: Establishing "Nitrate Vulnerable Zones" and implementing strict water quality controls.

   Circular economy: Turning problems into resources (using organic waste as safe fertilizers instead of synthetic chemicals).

  Demonstration No. 1: Digital Monitoring. Nitrate levels were measured in samples of mandarin, banana, kiwi, and drinking water using a portable field tester. The results were compared with the maximum permissible concentrations established by DSTU 4948:2008 (Fruits, Vegetables, and Processed Products: Methods for Determining Nitrate Content). It was emphasized that according to the primary EU regulation on contaminants in food - Regulation (EU) 2023/915 -mandatory nitrate limits apply only to specific categories of vegetables and baby food:

      Spinach (fresh, frozen, canned);

      Lettuce (fresh, of various types and growing seasons);

      Arugula;

      Baby food based on fruits and vegetables.

       The results of the testing, conducted with the participation of the lyceum students, are presented in the table and figure below, along with the interpretation of the analytical measurement data: 

Therefore, we do not recommend giving tropical and citrus fruits to children, especially those under the age of 1–1.5 years, or preparing homemade juices from them. These fruits can be a source of significant nitrate intake, which is much more toxic to children than to adults. The danger of using drinking water from decentralized sources exists when the water is drawn from unprotected aquifers that supply common wells.

  Demonstration No. 2: Classical Analytical Chemistry. Testing for Nitrate Anions - The “Brown Ring” Test.

       The description of this test became a standard in the mid-19th century. One of the scientists who thoroughly researched and popularized this method was the German analytical chemist Karl Remigius Fresenius. His works on qualitative analysis formed the foundation for how we conduct laboratory sessions in qualitative analysis today.

       The Essence of the Discovery: Chemists of that time were searching for a reliable way to distinguish nitrates from other salts. The challenge was that most nitrates are highly soluble in water, making them difficult to "precipitate." The reaction with iron(II) sulphate and concentrated sulphuric acid became an elegant solution.

       How It Works: Reduction: Sulphuric acid reacts with the nitrate, releasing nitric acid, which is then reduced by iron(II) to nitric oxide (NO).

       Complex Formation: This gas (NO) reacts with excess iron(II) ions to form a complex coordination compound.

       The Effect: It is this complex that has the characteristic dark brown colour. Since the reaction occurs at the interface of two liquid layers (the heavy acid and the lighter salt solution), a distinct ring is formed.

       Why Is This Historically Important? Before the advent of modern instruments (such as spectrophotometers or ion chromatography), this test was perhaps the only rapid way to detect nitrates in soil, water, or explosives. It requires minimal reagents but very “steady hands”, as shaking the test tube will cause the ring to disappear. This is a chemistry classic that helps verify data obtained from electronic sensors.

       Based on the results of the lecture session and chemical experiments conducted by the EU_NITRA_UKR project team, the following conclusions can be drawn:

      Sources of Danger: Agriculture remains the primary source of nitrate pollution (due to the uncontrolled use of fertilizers) alongside unprotected decentralized water sources (private wells).

      The Fruit Problem: The analysis revealed that nitrate levels in tropical fruits (banana, kiwi, and mandarin) significantly exceed established norms - ranging from 125 to 220 mg/kg, compared to the standard limit of 60-90 mg/kg. This makes them potentially hazardous for young children.

      Water Quality: Water from public buvette in Kyiv (using the water object which is situated near NUBiP as an example) is safe (9 mg/l). In contrast, well water (using a sample from the Poltava region) can be critically contaminated, exceeding the safety limit by 8.8 times.

      Analytical Methods: Combining modern digital testers with classical "wet chemistry" (the “brown ring” test) provides the most accurate and clear visual representation of contamination levels.

       PRACTICAL ADVICE FOR CONSUMERS

      To reduce the risk of nitrate intake, the following is recommended:

      Restrictions for children: Do not use tropical and citrus fruits to prepare homemade juices for children under 1.5 years old, as their bodies are most vulnerable to methemoglobinemia.

      Food preparation: Always wash vegetables and fruits thoroughly; trim the “tails” and stem attachment points, where nitrate concentrations are typically highest.

      Water monitoring: Residents of private housing who use wells must conduct regular laboratory water analysis, especially if agricultural lands or livestock farms are located nearby.

      Use of filters: For drinking water, it is recommended to use reverse osmosis systems or specialized ion-exchange filters that effectively remove nitrate anions.

DISCUSSION AND ECO-AWARENESS

During the discussion with the lyceum students, an important issue regarding the lack of state standards for nitrates in fruits was raised.

      EFSA Position: The European Food Safety Authority notes that under normal conditions, fruits accumulate significantly less nitrogen than leafy vegetables (spinach, arugula).

      The Reality: However, the experiment results demonstrated that imported off-season fruits can have high levels, requiring consumer vigilance.

      The Future: Transitioning to a circular economy and implementing the EU Nitrates Directive in Ukraine is a strategic step toward reducing chemical pressure on the environment and protecting national health.

The joint work of NUBiP scientists (the EU_NITRA_UKR project team) and the lyceum students highlighted a gap in Ukraine between regulations (where fruits are almost unregulated) and the actual state of products on store shelves. Implementing circular economy principles and moving away from excessive soil chemicalization is the only path to a safe future and clean drinking water for future generations.