Ultrasound assisted extraction and dispersive liquid–liquid microextraction with liquid chromatography-tandem mass spectrometry for determination of alkylphenol levels in cleaning products
The combination of the miniaturized techniques ultrasound assisted extraction (UAE) and dispersive liquid–liquid microextraction (DLLME) is used to measure levels of alkylphenols (APs) in cleaning products and detergents with an environmental impact. Detection was carried out using both diode-array (DAD) and electrospray-ion trap-tandem mass spectrometry (ESI-IT-MS/MS) in the multiple reaction monitoring mode (MRM) of the negative fragment ions for APs and in positive mode for ethoxylate APs (APEOs). Extraction was performed using an ultrasonic probe and acetonitrile, with 2 mL of acetonitrile extract, 100 μL carbon tetrachloride and 6 mL water selected as the DLLME parameters. The enriched organic phase was evaporated, reconstituted with 50 μL acetonitrile and injected into a liquid chromatograph with a mobile phase composed of acetonitrile/0.01 M ammonium acetate (pH 4.5) under gradient elution and a C8 stationary phase. Quantification was carried out using matrix-matched standards. Detection limits were in the range of 0.2–2.5 ng mL−1. The recoveries obtained were in the 91–120% range, with RSDs lower than 10.5%. The ESI-MS/MS spectra permitted the correct identification of both APs and APEOs in the samples. Twenty six different cleaning products were analyzed.