Simultaneous GC–MS determination of eight phthalates in total and migrated portions of plasticized polymeric toys and childcare articles
Introduction
Plastics have been widely used in our daily lives, as well as in numerous and varied industrial applications as a result of the multitude of the desirable properties they exhibit, including low cost, high durability, ease of manufacture and ability to recycle [1]. For plastic polymers to be ready for utilization, they have to undergo further processes, including mixing with other substances to make them capable of being processed to begin with, then to improve some desirable physicochemical properties and eliminate other undesirable properties. The other substances that are mixed with the plastic polymers are known as additives [2]. These additives may belong to main types of fillers, colorants, stabilizers, flame retardants, and plasticizers [3]. Plasticizers are substances that are mixed with the polymers in order to impart some desirable levels of flexibility and softness [4]. Plasticizers are liquids having low molecular weights that are not chemically bonded to the polymers; rather they are dispersed to spread through the polymer chains to interact with individual polymer chains, thus separating the individual chains from each other hence causing a significant reduction of the relatively stronger inter-polymer interactions, which result in an overall substantial increase of macromolecule mobility thus culminating in more flexible and elastic polymers [5]. Due to a favorable number of desirable properties they exhibit, phthalic acid esters (PAEs) are rated as the most commonly used plasticizers. In fact, phthalates constitute almost 80% of the global plasticizer production [6]; their use widely spread in plastics, particularly in PVC which consumes the largest share of annual phthalates production [7]. This raises a growing environmental concern about phthalates as probable health hazards to reckon with, especially since phthalates are not chemically bonded to the polymers which facilitate their leaching out of the polymer matrices into the surrounding environment [8]. This would certainly result in more worrying human exposure to PAEs from the profusion of a variety of PVC-based polymeric materials spread everywhere, especially those directly and frequently left in contact with children, including toys and various childcare articles; children and newborn babies tend to chew and suck their toys and other items, which might result in extracting the PAEs out of the plastic matrices and ingesting them thus exposing their health to the highly harmful PAEs. Research reported in the literature indicates the negative impact of PAE's on humans, stressing greater risks to the immune systems of children and newborn babies, and hence their general health. Among the health hazards reported in the literature include carcinogenity, kidney and liver damage, reproductive toxicity, and endocrine disruption [9], [10]. As a result, and according to the European Union Regulations REACH (Registration, Evaluation, Authorization and Restriction of Chemicals), six of the main phthalates have been banned, namely dibutyl phthalate (DBP), bis (2-ethylhexyl) phthalate (DEHP), benzyl butyl phthalate (BBP), di-“isononyl” phthalate (DINP), di-“isodecyl” phthalate (DIDP) and di-n-octyl phthalate (DNOP) [11]. In addition to those six PAEs, many others are still under discussion while some others have already been listed as candidates for labeling as Substances of Very High Concern (SVHCs), which depict substances that may have serious and often irreversible effects on human health and the environment, according to the European Chemical Agency ECHA definition [12], like bis(2-methoxyethyl)phthalate (DMEP) and di-“isobutyl” phthalate (DIBP). Fig. 1 depicts the chemical structures, the corresponding names and acronyms of the eight phthalates (PAEs) under consideration.
Several procedures have been used to analyze total PAEs such as Soxhlet extraction followed by GC/FID [8], GC/MS [13], simple shaking followed by GC/MS [14], ultra high performance liquid chromatography coupled with electronic spray mass spectrometry UPLCMS/MS [15]. Migration of PAEs into artificial saliva was analyzed after liquid–liquid extraction using GC/MS [16] and HPLC [17].
In this work, we were interested in developing and validating a method for the simultaneous determination of eight phthalate derivatives, in plasticized toys and childcare articles, using gas chromatography–mass spectrometry (GC–MS). These phthalates comprise the six restricted phthalates (DBP, BBP, DEHP, DNOP, DINP and DIDP), as well as two other phthalates that are considered substances of very high concern (DIBP and DMEP). The phthalates shall be determined as total and migrated phthalates in toys and childcare articles collected from the Jordanian market.
Section snippets
Reagents and chemicals
The phthalate standard reference materials were obtained as follows: dibutyl phthalate (DBP), 99.8%; bis (2-ethylhexyl) phthalate (DEHP), 99.7%; benzyl butyl phthalate (BBP), 98.7%; di-methoxyethyl phthalate (DMEP), 96.8%; and di-n-octyl phthalate (DNOP), 99.4% were all purchased from Fluka, Germany. Di-“isobutyl” phthalate (DIBP), 99.5% was purchased from Fluka, Switzerland, Di-“isononyl” phthalate (DINP), 99% was purchased from Aldrich, Germany, di-“isodecyl” phthalate (DIDP), 99% was
Optimization of the extraction parameters for the total PAEs
The extraction method using the ultrasonic bath was optimized by measuring the % recovery as a function of variation in the solvent type, temperature, extraction time and sample weight.
Using the MTBE solvent at R.T. for 30 min gave relatively low % recovery values (38.3–58.0%). Therefore, the first adjustment was to increase the extraction time from 30 min to 1, 1.5 and 2 h. The extraction efficiency was found to increase with an increase in extraction time yielding 42.2–62.2% recovery at 2 h,
Conclusion
Methods for determining the total PAEs and migrated PAEs into artificial saliva were developed and validated for routine analysis. The GC–MS technique was used to screen 8 PAEs. The developed and validated methods were used to survey the Jordanian market and to establish the relation between the corresponding total and the migrated values. It was found that as the concentration of PAEs increase, the migrated value increases. In contrast the migrated values decrease with an increase in the
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