A new multi-factor multi-objective strategy based on a factorial presence-absence design to determine polymer additive residues by means of head space-solid phase microextraction-gas chromatography-mass spectrometry

Abstract

A new multi-factor multi-objective strategy to approach the joint assessment of the effect of six experimental factors in the determination by head space-solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) of eight different additives commonly used in the plastic packaging manufacturing is proposed in this work. Five HS-SPME experimental factors, both qualitative and quantitative, are explored: the type of fiber, addition of salt, extraction and desorption time, and extraction temperature. The effect of these factors is studied through a factorial presence-absence model, that include interactions, using a D-optimal design. As a result, the number of experiments is reduced from 128, full factorial design, to 14. The effect of carrying out the measurements in different experimental sessions is considered by including a blocking factor. The response for each compound is estimated in the experimental domain and then the best experimental conditions are chosen by using Pareto front. Parallel coordinates are employed to show the conflicting conditions intrinsic to a multi-objective analysis when compounds of different nature are extracted by HS-SPME. Parallel factor analysis 2 (PARAFAC2) decomposition is used because it makes the determination of target compounds in the presence of unknown interferents possible, which enables the unequivocal identification of target compounds according to official regulations. The developed method is applied to determine 2,6-di-tert-butyl-4-methyl-phenol (BHT), benzophenone (BP), bis(2-ethylhexyl) adipate (DEHA), diethyl phthalate (DEP), diisobutyl phthalate (DiBP), dibutyl phthalate (DBP), benzyl butyl phthalate (BBP) and bis(2-ethylhexyl) phthalate (DEHP). The level of these compounds found in nine types of bottled natural still and sparkling mineral waters is very low, so the compounds were not present in quantities that may be injurious to human health.