Adsorption of azithromycin in agricultural soils of the Bogotá savanna, Colombia.

Azithromycin is one of the most widely used macrolide antibiotics in medical treatment. However, there is little information on studies of the ecotoxicity, persistence and mobility of this type of compounds in the environment, although their presence in surfaces and wastewater has already been detected (Hernández et al., 2015). Based on this approach, the present research performs an analysis of the behavior of the adsorption process of azithromycin in soils of different textural classes, with the intention of establishing a first approach to assess the destination and transport of such substances in the biosphere. From the results of the evaluation of the conditions of adsorption of azithromycin, it is established that the Langmuir model has a better fit for clay soils with correlation coefficients R2 between 0.998 and 0.961. In contrast, the Freundlich model fits the soil with higher sand fraction with a higher correlation, R2 of 0.9892. Finally, based on a correlation analysis between the clay content, the percentage of organic matter and the adsorption coefficient K, it was evident that the adsorption of azithromycin is mainly related to the inorganic fraction of the soil.

LC-QTOF MS screening of more than 1,000 licit and illicit drugs and their metabolites in wastewater and surface waters from the area of Bogotá, Colombia.

A large screening of around 1,000 emerging contaminants, focused on licit and illicit drugs and their metabolites, has been made in urban wastewaters (both influent and effluent) and surface waters from the area of Bogotá, Colombia. After a simple generic solid-phase extraction (SPE) step with Oasis hydrophilic-lipophilic balanced (HLB) cartridges, analyses were made by ultra high-performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (UHPLC-QTOF MS) under MS(E) mode (sequential acquisition of mass spectra at low energy (LE) and high collision energy (HE)). Accurate mass measurements and the information provided by MS(E) on the presence of the (de)protonated molecule and fragment ions allowed the reliable identification of the compounds detected, even without reference standards being available in some cases (tentative identification). The compounds most frequently found were acetaminophen/paracetamol, carbamazepine and its dihydro-dihydroxylated metabolite, clarithromycin, diclofenac, ibuprofen, gemfibrozil, lincomycin, losartan, valsartan, the two metabolites of metamizole (4-acetamido-antipyrine and 4-formylamino-antipyrine), sucralose, and cocaine and its main metabolite benzoylecgonine. Caffeine, the sweetener saccharin, and two hydroxylated metabolites of losartan were tentatively identified in almost all samples analyzed. Pharmaceutical lidocaine was tentatively identified and subsequently confirmed with reference standard. For the first time, a general overview of the occurrence of drugs and their metabolites in the aquatic environment of Colombia has been reported. In the near future, target methodologies, typically based on liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS), will need to be set up for accurate and sensitive quantification of the contaminants selected on the basis on the information provided in the present paper.