Combined microwave-assisted extraction and continuous solid-phase extraction prior to gas chromatography–mass spectrometry determination of pharmaceuticals, personal care products and hormones in soils, sediments and sludge

This paper reports a sensitive analytical method based on microwave-assisted extraction and continuous solid-phase extraction (SPE), followed by gas chromatography–mass spectrometry (GC−MS), for the simultaneous determination of residues of 18 pharmaceuticals (analgesics, antibacterials, anti-epileptics, β-blockers, lipid regulators and non-steroidal anti-inflammatories), one personal care product and 3 hormones in soils, sediments and sludge. The analytes are extracted with 3:2 methanol/water under the action of microwave energy and the resulting extract is passed through a SPE column to clean up the sample matrix and preconcentrate the analytes. Then, the analytes, trapped on Oasis-HLB sorbent, are eluted with ethyl acetate, silylated and determined by GC–MS. The proposed method provides a linear response over the concentration range 2.5–20 000 ng/kg with correlation coefficients higher than 0.994 in all cases. Also, it features low limits of detection (0.8–5.1 ng/kg), good precision (within- and between-day relative standard deviation less than 7%) and recoveries ranging from 91 to 101%. The method was successfully applied to agricultural soils, river and pond sediments, and sewage sludge. All samples contained some target analyte and sludge contained most —some at considerably high concentrations.

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► A new approach for the determination of 22 pharmaceuticals in soils is presented.
► Miniaturization of the sample treatment system using a MAE and a continuous SPE unit.
► Low limits of detection (between 0.8 and 5.1 ng/kg) were achieved.
► All samples analysed contained some target analyte (8.5–3100 ng/kg).