Diclofenac and Ibuprofen Determination in Sewage Sludge Using a QuEChERS Approach: Occurrence and Ecological Risk Assessment in Three Nigerian Wastewater Treatment Plants.

A quick, easy, cheap, effective, rugged and safe (QuEChERS) method was optimized for the extraction of non-steroidal anti-inflammatory drugs (NSAIDs) diclofenac and ibuprofen from sewage sludge. Dispersive-solid phase extraction (d-SPE) was employed for sample clean-up. Instrumental analysis was performed by high-performance liquid chromatography. Ecological risk was assessed for four trophic levels: fish, daphnia, algae and bacteria. The method limits of quantification for diclofenac and ibuprofen were 0.43 µg g and 0.45 µg g, respectively. Correlation coefficients were above 0.999. Extraction recoveries ranged from 70 to 118 % and satisfactory inter-day reproducibility (% RSD) of < 18 % was obtained. Diclofenac and ibuprofen were measured up to 1.02 µg g and 6.6 µg g, respectively in sewage sludge from three Nigerian wastewater treatment plants (WWTPs). Ibuprofen posed high risk to fish, daphnia, algae and bacteria. This work presents the first report on the ecological risk assessment of diclofenac and ibuprofen in sewage sludge from Nigerian WWTPs.