Oxidized carbon nanotubes as sorbent for miniaturized solid-phase extraction of progestins from environmental water samples prior to their determination by HPLC-UV.

A solid-phase extraction method is presented for micro-extraction of three progestins (levonorgestrel, 19-norethisterone acetate and medroxyprogesterone acetate) from water samples. A mini-column was packed with 60 mg of oxidized multiwalled carbon nanotubes and coupled to a flow injection assembly. The extraction parameters, such as washing solution, eluent type, eluent volume, flow rate and sample volume, were optimized. Separation and determination were performed by HPLC with UV detection. The method has a good linear range (0.90-9.0 μg L-1), acceptable limits of detection (0.05-0.14 μg L-1) and low RSDs (0.8-4.6%). Attractive features of the method include low consumption of organic solvents and preconcentration factors of up to 100. The method was applied to analyze stream, underground and effluent water samples, and recoveries between 74 and 121% were obtained. Graphical abstractSchematic representation of the flow injection assembly couples to an ox-MWCNTs extraction column used to perform the solid phase extraction procedure of progestins in environmental water samples.