LC-MS/MS performance results are available in the supplementary information (table ). iMME -LC-MS/MS performance and SPE recoveries for the CECs studied are gathered in figure 3. Good recoveries were observed generally (93 ± 32%); particularly compounds from the illicit drugs classes (~116%) and the betablockers (~110%). Regarding AAs, parent analytes from the sulfonamides and macrolides generally had good recoveries from river water samples (87% and 97%, respectively). The metabolite recoveries for sulfonamides and macrolides AAs did vary; with some performing well, like desmethylerythromycin (108%), and others observing lower recoveries, such as acetyl-sulfamethoxazole (47 %).