Comparison of ultrasound-assisted extraction, QuEChERS and selective pressurized liquid extraction for the determination of metabolites of parabens and pharmaceuticals in sludge

Abstract Analytical methods for the determination of parabens and pharmaceuticals in sludge are scarce and focused on the parent compounds in spite that metabolites can be more toxic and concentrated. This fact is of special relevance when sewage sludge is applied as soil fertiliser what is a common practise in many European countries. In that way, they could affect soils and plants and could even enter into the food chain. In this work, to cover the lack of methodologies for the determination of metabolites of parabens and pharmaceuticals in sludge, two analytical methods have been developed. Proposed analytical methods are based on low-cost and easy-to-perform techniques (ultrasonic-assisted extraction (UAE) and QuEChERS) to make them affordable for routinely control laboratories. The methods have been optimised and validated for the determination of 12 relevant metabolites of parabens and pharmaceuticals and their 7 parent compounds. Proposed methods have been compared with a previously reported method based on selective pressurised liquid extraction (SPLE). UAE method provided higher recoveries, lower MQL, higher precision and higher accuracy than QuEChERS method. Nevertheless, both QuEChERS and UAE methods, in spite of being more time-consuming and difficult to automatise, have been demonstrated to be suitable low-cost alternatives to SPLE. To the best of our knowledge, UAE, QuEChERS and SPLE proposed methods constitute the first multiresidue methods for the simultaneous determination of metabolites of parabens and pharmaceuticals in sewage sludge.