Optimization of a GC/MS procedure that uses parallel factor analysis for the determination of bisphenols and their...

Bisphenol A (BPA), bisphenol F (BPF) and their corresponding diglycidyl ethers (BADGE and BFDGE) are simultaneously determined using a programmed-temperature vaporizer-gas chromatography/mass spectrometry (PTV-GC/MS) system. BPA is used in the production of polycarbonate (PC), whereas BADGE and BFDGE are for manufacturing epoxy resins. Several food alerts caused by the migration of this kind of substances from contact food materials have led to the harmonization of the European legislation in Commission Regulation (EU) No. 10/2011, in force from 14 January 2011. In consequence, the use of BPA has been prohibited in the manufacture of plastic infant feeding bottles from 1 May 2011 and from 1 June 2011 regarding the placing on the market and importation into the European Union. Recently, the French Parliament has decreed that the presence of BPA in any food containers will be banned. Similarly, the use and/or presence of BFDGE are not allowed. In this work, a GC/MS method has been developed for the simultaneous determination of BPF, BPA, BFDGE and BADGE. For each one of the I samples that are analyzed, the abundance of J characteristic m/z ratios is recorded at K times around the retention time of each peak, so a data tensor of dimension I×J×K is obtained for every analyte. The decomposition of this tensor by means of parallel factor analysis (PARAFAC) enables to: (a) identify unequivocally each analyte according to the maximum permitted tolerances for relative ion intensities, and (b) quantify each analyte, even in the presence of coeluents. This identification, based on the mass spectrum and the retention time, guarantees the specificity of the analysis. This specificity could fail if the total ion chromatogram (TIC) is considered when there is poor resolution between some peaks or whether interferents coelute. With the aim of studying the effect of shortening the time of the analysis on the quality of the determinations while maintaining the specificity of the identifications, two of the heating ramps in the oven temperature program are changed according to a two-level factorial design. Each analyte is identified by means of a PARAFAC decomposition of a data tensor obtained from several concentration levels, in such a way that five figures of merit are calculated for each experiment of the design. The analysis of these figures of merit for the 16 objects (4 compounds×4 heating ramps) using principal component analysis (PCA) shows that the shortest temperature program should be considered, since this is the one the best figures of merit for BPA and BFDGE (both banned) are achieved with. At these conditions and with probabilities of false positive and false negative fixed at 0.05, values of detection capability (CCβ) between 2.65 and 4.71 μg L(-1) when acetonitrile is the injection solvent, and between 1.97 and 5.53 μg L(-1) when acetone, are obtained. This GC/MS method has been applied to the simultaneous determination of BPF, BPA, BFDGE and BADGE in food simulant D1 (ethanol-H2O, 1:1 v/v), which had been previously in contact with PC tableware for 24h at 70 °C and then pretreated by a solid-phase extraction (SPE) step. The migration of BPA from the new PC containers analyzed is confirmed, and values between 104.67 and 181.46 μg L(-1) (0.73 and 1.27 μg L(-1) after correction) of BPA have been estimated. None of the results obtained exceeds the specific migration limit of 600 μg L(-1) established by law for BPA in plastic food materials different from PC infant feeding bottles. Severe problems of coelution of interferents have been overcome using PARAFAC decompositions in the analysis of these food simulant samples.