Determination of cardiovascular drugs in sewage sludge by matrix solid-phase dispersion and ultra-performance liquid chromatography tandem mass spectrometry

The current study presents a single step sample preparation procedure for the simultaneous determination of five antihypertensive (propranolol, losartan, irbesartan, telmisartan, and valsartan), three antiarrhythmic drugs (flecainide, dronedarone, and amiodarone), and one of their metabolites (N-desethylamiodarone) in sludge from municipal sewage treatment plants (STPs). Matrix solid-phase dispersion (MSPD) and ultra-performance liquid chromatography (UPLC) with tandem mass spectrometry (MS/MS) detection were selected as sample preparation and determination techniques, respectively. Under optimal conditions, MSPD extractions were carried out with freeze-dried samples (0.5 g) dispersed on 2 g of C18. Exhaustive extraction of target compounds was achieved with 10 mL of a methanol/acetonitrile/formic acid (30:69:1) solution. The obtained extract was ready for UPLC-MS/MS analysis without any further treatment, except filtration. The overall recoveries of the method (calculated against solvent-based standards) varied from 82 to 124%, with standard deviations in the range from 2 to 16%. Thus, the method was free of matrix effects during electrospray ionization. The achieved limits of quantification stayed between 2 and 10 ng g−1, and the linear response range extended to 5000 ng g−1. The occurrence of target compounds was investigated in sludge from 14 different STPs. High detection frequencies were observed for all compounds, with average concentrations above 100 ng g−1 for six cardiovascular drugs.