Determination of phthalate esters in cleaning and personal care products by dispersive liquid-liquid microextraction and liquid chromatography-tandem mass spectrometry

Phthalic acid esters (PEs) were preconcentrated from cleaning products, detergents and cosmetics using ultrasound assisted extraction (UAE) in the presence of acetonitrile, and then submitted to dispersive liquid-liquid microextraction (DLLME). For DLLME, 3 mL of acetonitrile extract, 150 μL carbon tetrachloride and 10 mL aqueous solution were used. The enriched organic phase was evaporated, reconstituted with 25 μL acetonitrile and injected into a liquid chromatograph with a mobile phase (acetonitrile:10 mM ammonium acetate, pH 4) under gradient elution. 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 positive fragment ions. Quantification was carried out using matrix-matched standards. Detection limits were in the range 0.04-0.45 ng mL−1 for the six PEs considered. The recoveries obtained were in the 84-124% range, with RSDs lower than 10%. Thirty three different cleaning products were analyzed. The most frequently found compound was diethyl phthalate.