Determination of nonylphenol and nonylphenol ethoxylates in environmental solid samples by ultrasonic-assisted extraction and high performance liquid chromatography-fluorescence detection

A simple and rapid analytical method for the determination of nonylphenol (NP) and nonylphenol ethoxylates (NPEOx) in solid environmental samples has been developed. This method combines an ultrasonic-assisted extraction procedure in small columns and an enrichment step onto C18 solid-phase extraction cartridges prior to separation using HPLC with fluorescence detection. Method optimization was carried out using soil samples fortified at different concentration levels (from 0.1 to 100 μg/g). Under optimum conditions, 2 g of soil was placed in small glass columns and extraction was performed assisted by sonication (SAESC) at 45 °C in two consecutive steps of 15 min using a mixture of H2O/MeOH (30/70). The obtained extracts were collected, loaded onto 500 mg C18 cartridges, and analytes were eluted with 3 × 1 ml of methanol and 1 ml of acetonitrile. Finally, sample extracts were evaporated under a nitrogen stream, redissolved in 500 μl H2O/AcN (50/50), and passed though a 0.45 μm nylon filter before final determination by HPLC-FL. The developed procedure allowed to achieve quantitative recoveries for NP and NPEOx, and was properly validated. Finally, the method was applied to the determination of these compounds in soils and other environmental solid samples such as sediments, compost and sludge.