Innovative sampling and extraction methods for the determination of nonsteroidal anti-inflammatory drugs in water.

Two different innovative approaches were used for the determination of nonsteroidal anti-inflammatory drugs (NSAIDs) in water: stir bar sorptive extraction (SBSE) and passive sampling, followed by electrospray ionization liquid chromatography-tandem mass spectrometry. SBSE was developed by comparing EG-Silicone and PDMS stir bars and optimizing main parameters to attain high preconcentration. Quantitative analysis was carried out by mass spectrometry in negative ionization mode and multiple reaction monitoring. The SBSE-LC-MS/MS method provided satisfactory figures of merit with LOD (7.5-71 ng L(-1)) and LOQ (22.5-213 ng L(-1)). The developed method was successfully applied to real samples collected from river water and wastewater effluents. The obtained results showed the presence of all analytes at trace levels, in a wide range of concentrations. The passive sampling approach was carried out by using Polar Organic Chemical Integrative Sampler (POCIS); samplers were deployed for 15 days in river and tap water, allowing to detect analytes at ultra-trace levels. Time-Weighted Average concentration of NSAIDs in river water was estimated in the range 0.33-0.46 ng L(-1), using the sampling rates previously obtained by means of a simple calibration system.