Multiclass ultrasound-assisted extraction, clean-up and high performance liquid chromatography-tandem mass spectrometry quantification of steroid hormone residues in compost.

An analytical method for multiclass determination of steroid hormones in compost has been developed to fill the lack of methods for steroid residuals monitoring in this waste-derived product, increasingly produced and recycled in the circular-economy approach. The procedure simply entails an ultrasound-assisted extraction (UAE) on 300 mg compost by 3 × 2.5 mL methanol × 5 min sonication steps followed by a quick clean-up by solid-phase extraction (SPE) on the silica-based Supelclean™ LC-NH that avoids use of organic solvents. The clean extract is analysed by HPLC-MS/MS achieving firm identification and quantitation of the 16 steroids, i.e., glucocorticoids, progestins, androgens, oestrogens. The analytical figures of merits were assessed, viz. selectivity, sensitivity, linearity, matrix effect, trueness, precision, carry-over and robustness, in line with updated guidelines. Recovery was investigated in the concentration range 15-800 ng g, and at the quality control levels (15, 50, 200 and 400 ng g) was in the range 60-120%, with inter-day precision RSDs < 20% (n = 3). The experimental quantification limit was 15 ng g for all the hormones. The method was applied to analysis of different compost samples proving to be functional to environmental monitoring.