Pressurized liquid extraction (PLE) and liquid chromatography – tandem mass spectrometry (LC/MS/MS) for determination of Bisphenol A, Octylphenol and Nonylphenol in infant formulas.

During the last decade there has been a worldwide scientific and public discussion about the potential consequences of long-term dietary exposure to endocrine disrupters. Bisphenol A (BPA) is a substance widely used for the manufacture of polycarbonate plastics and epoxy resins, which are used in plastic food containers, such as baby bottles. Nonylphenol (NP) and Octylphenol (OP) are intermediates to produce anionic and non-ion surfactants and are environmental contaminants [1]. Some recent reports determined the occurrence of these endocrine disruptor compounds in foods from different markets or containers; also, studies with the migration of BPA from baby bottles are available [2]. In April 2008, Health Canada released its Draft Screening Assessment for BPA, which concluded that the chemical may pose some risk to infants and proposed classifying the chemical as “toxic” to human health and environment. The aim of this work was to develop a new rapid, sensitive and reproducible analytical strategy for determining BPA, OP and NP content in powdered infant formulas using pressurized liquid extraction (PLE) and liquid chromatography-tandem mass spectrometry (LC/MS/MS) with a triple quadrupole (QqQ) mass analyzer. For the extraction of the sample a comparative study was carried out using as dispersing agent C18 powder, and testing various solvents as dicloromethane, acetone, hexane, methanol, acetonitrile, and the mixture of them. The separation was carried out on a reverse phase C18 column using as mobile phase methanol/acetonitrile/water containing 0.1% ammonia. LC/MS/MS studies were performed using a QqQ equipped with an electrospray ionization (ESI) source operating in negative mode. Calibration curves, calculated in the range 0.05-5 g ml-1, showed excellent linearity (r2>0.998). The recoveries ranged from 63 to 91% with an RSD < 12%; limits of quantification (LOQs) were in the range 0.5-2.5 ng ml-1. PLE coupled with LC/ESI/MS/MS enables rapid and accurate determination of BPA, NP and OP in infant formulas. [1] B. Shao et al. Food Chem., 2007, 105, 1236. [2] N.C. Maragou et al. Food Addit. Contam., 2008, 25, 373