Effect of the cleaning procedure of Tenax on its reuse in the determination of plasticizers after migration by gas chromatography/mass spectrometry.

This paper presents the simultaneous determination of a UV stabilizer (benzophenone (BP)) together with four plasticizers (butylated hydroxytoluene (BHT), diisobutyl phthalate (DiBP), bis(2-ethylhexyl) adipate (DEHA) and diisononyl phthalate (DiNP)) in Tenax by gas chromatography/mass spectrometry and PARAFAC, using DiBP-d4 as internal standard. Regulation (EU) No. 10/2011 establishes Tenax as food simulant E for testing specific migration from plastics into dry foodstuffs. This simulant must be cleaned before its use to eliminate impurities. Tenax is expensive, so its reuse would save costs. A two-way ANOVA was used to study some parameters affecting the cleaning and the extraction of Tenax. The most adequate conditions were chosen taking the values of the coefficient of variation and the average recovery rates of spiked Tenax samples into account. A study to determine if some analytes remain in Tenax when it is reused and the effect that the cleaning procedure may have in the adsorption capability of Tenax was proposed. This study led to the conclusion that Tenax could not be reused in this multiresidue determination. All the analytes were unequivocally identified in all the stages of this work and trueness was verified at a 95% confidence level in all cases. A calibration based on PARAFAC provided the following values of capability of detection (CCβ): 2.28 µg L-1 for BHT, 10.57 µg L-1 for BP, 7.87 µg L-1 for DiBP, 3.04 µg L-1 for DEHA and 124.8 µg L-1 for DiNP, with the probabilities of false positive and false negative fixed at 0.05. The migration of the analytes from a printed paper sample into Tenax was also studied. The presence of BHT in the food simulant was confirmed and the amount released of this analyte from the paper was 2.56 μg L-1 .