Development of monolithic sorbent cartridges (m-SPE) for the extraction of non-steroidal anti-inflammatory drugs from surface waters and their determination by HPLC

Abstract

A novel and simple analytical methodology including solid-phase extraction using a monolithic sorbent (m-SPE), coupled to reverse phase liquid chromatography analysis, to determine seven non-steroidal anti-inflammatory drugs in surface water samples, is proposed. The sorbent was easily prepared though a thermal polymerization reaction by using a mixture of 2-hydroxyethyl methacrylate as polar monomer, ethylene glycol dimethacrylate as crosslinker, a porogenic solvent (1-dodecanol/cyclohexanol) and a radical initiator (lauroyl peroxide) contained in a typical syringe cartridge. The effect of different parameters on the extraction efficiency, were optimized by experimental design obtaining as optimal values: 465 µL of the polymerization mixture used for the sorbent and 0.85 mL min−1 for the sample charge flow at pH 3.15. Different elution solvents were studied; however acetonitrile was the most efficient. Under the optimized experimental conditions, linearity was established in the broad range of 3 to 500 µg L−1, enrichment factors were between 47 and 54, relative recovery factors from 94 to 107%, accuracy values in the range of 0.2 to 7.5%, and inter-cartridge reproducibility values between 1 and 7%, were obtained. The limits of detection and quantification were obtained by three different procedures: i) S/N = 3 and 10, ii) 3,3SD/b and 10SD/b, and iii) the IUPAC recommendations. The lowest ranges, obtained with the procedure i, were from 1.0 to 2.6 µg L−1 and 3.2 to 8.7 µg L−1, for the detection and quantification limits, respectively. Ibuprofen, naproxen and indoprofen were detected in samples taken from creeks located in La Plata city (Buenos Aires Province, Argentina) but only ibuprofen could be quantitatively determined.