Since early 2020, the COVID-19 pandemic has brough a series of challenges and lesson to be learnt, and with these trials new approaches have raised, like the wastewater-based epidemiology. In this work, we developed an analytical method based on HPLC-ESI-MS/MS to quantify in wastewater five pharmaceutical compounds used to cope with the symptoms of COVID-19, namely azithromycin, ivermectin, dexamethasone, famotidine and indomethacin. Sewage samples were collected at several points from Mexico City and the Mezquital Valley in a one-year monitoring campaign; also, natural water samples were taken in Mezquital Valley, where Mexico City’s wastewater infiltrates through soil to recharge the aquifer. Out of the five target compounds, azithromycin, ivermectin and dexamethasone were consistently detected in Mexico City’s wastewater, at levels of 100-250 ng/L. Concentration of famotidine and indomethacin were negligible in wastewater and natural water samples. The concentration profile of the pharmaceuticals matched well with the number of positive cases in Mexico City, suggesting that they can be as a surveillance approach to follow the spread of the disease in Mexico City, now that sense of thereat has diminished. For wastewater samples taken in Mezquital Valley, the concentration of dexamethasone was below the limit of detection of the analytical technique, which was attributed to dilution effect and possibly degradation in wastewater. The concentration of azithromycin and ivermectin was drastically reduced by the infiltration of wastewater through soil, pointing out the importance of soil to remove these pollutants via biotic and abiotic processes.

https://zoom.us/j/98872850740?pwd=Uks3V0RlRGNCbmR1alBpY2VBZHFFdz09