Target analysis of contaminants of emerging concern in surface water of the Great Bačka Canal

Municipal and industrial wastewater discharges are the primary pathways through which contaminants of emerging concern (CECs) enter aquatic systems. In areas with highly developed agriculture, such as the Vojvodina region, the use of surface water for irrigation raises concerns due to the potential presence of CECs.

This study aims to quantify CECs in the Great Bačka Canal using target analysis of preselected list of compounds. The target CECs were selected based on previously conducted suspected screening analysis (SSA) using high resolution mass spectrometry . A total of 120 grab samples of surface water were collected along the entire length of the canal during three campaigns (spring, summer and autumn in 2024). Sample preparation was conducted using solid-phase extraction (SPE) with a custom-made multi-sorbent cartridge consisting of 200 mg of Oasis HLB sorbent in the upper, and a mixture of 150 mg of Bond Elut PPL, 100 mg of WAX, and 100 mg of WCX in the lower layer. Prior to instrumental analysis, internal standard mixture (40 ng/mL) was added to the final extract.

Target analysis was performed on ultra-high-performance liquid chromatography (Accela™ system, Thermo Fisher Scientific, USA) coupled to triple-quadrupole mass spectrometry (MS/MS) (TSQ Vantage, Thermo Fisher Scientific, USA) equipped with a heated electrospray ionization source (HESI-II, Thermo Scientific, USA). The Waters Acquity HSS T3 (C18) column (100×2.1 mm i.d., 1.8 μm particle size) was used for chromatographic separation.

Among the 30 detected compounds, pharmaceuticals (16 compounds) and pesticide residues (7 compounds) were the most common. They were followed by pharmaceuticals transformation products, hormones and sweeteners with 2 compounds each and one industrial chemical. Across all analyzed samples, the concentrations of identified CECs ranged from below the detection limit to 955 ng/L, with overall median and mean values of 28.80 ng/L and 8.39 ng/L, respectively.

Acknowledgment: Acknowledgement - This research was supported by the Science Fund of the Republic of Serbia, #GRANT No. 7335, Sustainable environmental monitoring and prediction of pollutants spread - EnviLife.