Environmental risk assessment of pharmaceutical pollutants in the Oro River Sub-basin (Colombia).

Pharmaceuticals and Personal Care Compounds (PPCPs) are contaminants present in wastewater and in the receiving surface waters, which have no regulations and can bring on environmental risks. In this study, we evaluated the presence of six PPCPs in the Oro River Sub-basin (Colombia) and the environmental risk associated with them. We have verified that the monitored rivers show the presence of Ibuprofen, Cephalexin and Carbamazepine; the first ones (Ibuprofen and cephalexin) were those that presented higher concentrations since they are widely prescribed in Colombia. Pharmaceutical compound concentrations in the rivers downstream of the wastewater treatment plants from Floridablanca were higher than in other monitoring sites being a significant point source of contamination. This wastewater treatment plant receives hospital discharges from the city, including internationally recognized clinics accepting patients from different parts of the country. The environmental risk assessment showed that ibuprofen and Cephalexin have a higher impact on aquatic organisms.

Fluorescent nanostructured carbon dot-aptasensor for chlorpyrifos detection: Elucidating the interaction mechanism for an environmentally hazardous pollutant.

Chlorpyrifos (CPF) is a commonly used insecticide found in many water sources and is related to several health and environmental effects. Biosensors based on aptamers (single-stranded nucleic acid oligonucleotides) are promising alternatives to achieve the detection of CPF and other pesticides in natural waters. However, several challenges need to be addressed to promote the real application of functional aptasensing devices. In this work, an ssDNA aptamer (S1) is combined with carbon quantum dots (CD) and graphene oxide (GO) to produce a stable fluorescent aptasensor characterized through spectrophotometric and electrophoretic techniques. For a deeper understanding of the system, the mechanism of molecular interaction was studied through docking modeling using free bioinformatic tools like HDOCK, showing that the stem-loops and the higher guanine (G) content are crucial for better interaction. The model also suggests the possibility of generating a truncated aptamer to improve the binding affinity. The biosensor was evaluated for CPF detection, showing a low LOD of 0.01 µg L-1 and good specificity in tap water, even compared to other organophosphates pesticides (OPs) like profenofos. Finally, the recovery of the proposed aptasensor was evaluated in some natural water using spiked samples and compared with UPLC MS-MS chromatography as the gold standard, showing a good recovery above 2.85 nM and evidencing the need of protecting ssDNA aptamers from an erratic interaction with the aromatic groups of dissolved organic matter (humic substances). This work paves the way for a better aptasensors design and the on-site implementation of novel devices for environmental monitoring.

QuEChERS GC-MS validation and monitoring of pesticide residues in different foods in the tomato classification group.

The objective of this study was to validate (SANCO/12495/2011 and NTC-ISO/IEC 17025) multi-residue multi-class methods using QuEChERS sample preparation and GC-MS for the analysis of regulated pesticides in tomatoes (Solanum lycopersicum), tamarillos (Solanum betaceum) and goldenberries (Physalis peruviana). These Latin American products are representative and widely produced in Antioquia (Colombia). Sample preparation followed the UNE-EN 15662 method (150 mg MgSO4, 25mg primary secondary amines and 25mg of octadecylsiloxane for cleanup; graphitized carbon black was added for tomatoes). Extracts were injected using a programmed temperature-vaporizing injector. The residues were validated over a range from 0.02 mg/kg to 0.20 mg/kg, with 24 analytes validated in tomatoes, 33 in tamarillos and 28 in goldenberries. An initial risk assessment was enabled by monitoring 24 samples in the municipalities of El Peñol, Marinilla and San Vicente Ferrer. Risks were found for tomatoes, but no significant risks were found for tamarillos or goldenberries.