Elsevier

Journal of Chromatography B

Volumes 949–950, 15 February 2014, Pages 99-108
Journal of Chromatography B

Identification and quantification of 14 phthalates and 5 non-phthalate plasticizers in PVC medical devices by GC–MS

https://doi.org/10.1016/j.jchromb.2013.12.037Get rights and content

Highlights

  • A total of 14 phthalates and 5 non-phthalate plasticizers are quantified by GC/MS.

  • Validation data on standard solution were obtained using the ISO 12787 standard.

  • Recoveries obtained on spiked preparations for all analytes are given.

  • A cross-validation of the DEHP extraction using the Ph. Eur. 3.1.14 is given.

  • Results obtained on 61 medical devices and 12 raw materials are discussed.

Abstract

A GC/MS method was developed for the identification and quantification of 14 phthalates: 8 phthalates classified H360 (DBP, DEHP, BBP, DMEP, DnPP, DiPP, DPP and DiBP), 3 phthalates proposed to be forbidden in medical devices (DnOP, DiNP and DiDP) and 3 other phthalates none regulated (DMP, DCHP and DEP) which may interfere with hormone function. In order to identify and quantify other plasticizers that are commonly used in PVC medical devices such as DEHP substitute, 5 non-phthalate plasticizers (ATBC, DEHA, DEHT, TOTM, and DINCH) were included in this study. Analyses are carried out on a GC/MS system with electron impact ionization mode (EI). The separation of plasticizers is obtained on a cross-linked 5%-phenyl/95%-dimethylpolysiloxane capillary column 30 m × 0.25 mm (i.d.) × 0.25 μm film thickness using a gradient temperature. Compounds quantification is performed by external calibration using an internal standard. Validation elements on standard solutions were determined using the ISO 12787 standard approach. Plasticizers are extracted from PVC medical devices using THF for dissolving the PVC part of the sample followed by precipitation of the PVC by addition of ethanol. The supernatant is injected into a GC/MS system after dilution in ethanol. Different validation elements, including extraction recoveries for all compounds or for DEHP a cross-validation of the extraction process using the European pharmacopoeia monograph 3.1.14 as reference method, are discussed. Results obtained on 61 medical devices in PVC and 12 raw materials used as plasticizers are given.

Introduction

Phthalates are esters of ortho-phthalic acid. These compounds have applications in many industrial sectors. They are used as plasticizers to improve flexibility of plastics such as polyvinyl chloride (PVC) in which they can represent up to 40% of the total mass [1]. As phthalates are not chemically bound to plastics, these compounds may be released from plastics used for medical devices [2], [3], [4], [5], [6]. Suspicions of harmful effects of phthalates on human health have recently been brought to the attention, even if phthalate esters toxicity is already known since 1950s [7]. Phthalates may be involved in reprotoxicity, carcinogenesis, cardiotoxicity, hepatotoxicity and nephrotoxicity [8], [9], [10]. Experiments on animals have shown that phthalates may also have influence on immune and allergic response, even if effects observed in rodents regarding immune toxicity may not be relevant to humans based on much lower human exposure and on the route of human exposure [11]. One of the main potential toxic effects of some phthalates experimentally observed concerns the human endocrine system [12], [13]. A study published in 2013 reports significant increased mono(2-ethylhexyl)phthalate (MEHP) blood levels in pregnant women upon recent exposure to perfusion materials [14]. According to the Directive 2007/47/EC (7.5) requirement, manufacturers must indicate on the labelling of the medical device or on the medical device itself the presence of any compound carcinogenic, mutagenic or toxic to reproduction in accordance with Directive 67/548/EEC (Annex I). Still nowadays, no target value exists beyond which the “phthalates” or “DEHP” label must be mentioned on medical devices.

In 2013, the only official method for the determination of phthalates as ingredients in plastic materials used for medical devices is mentioned in the European pharmacopoeia (monograph 3.1.14) [1]. This official method, focused exclusively on the determination of DEHP as plasticizer, is based on the extraction of this phthalate from PVC materials with diethyl ether using a reflux condenser. The extraction solvent (diethyl ether) is then completely evaporated and the dry residue dissolved in toluene. The analysis is performed using thin layer chromatography. As part of a recent study, published by our laboratory and focused on the determination of phthalates in cosmetic products, analytical methods proposed in the literature for the identification and separation of phthalates were studied and reported [15]. Among analytical methods existing [16], [17], [18], [19], [20], [21], [22], [23], [24], [25], [26], HPLC/UV is one of the methods used for the separation, identification and quantification of phthalates [16], [17], [18], [20], [21], [22]. Few numbers of phthalates are simultaneously determined by these methods. Indeed, most articles propose analytical methods for the separation of 4 or 5 phthalates among which only 2 or 3 are classified H360 (BBP, DEHP and DBP). Only one HPLC/UV method [20] proposes the separation of up to 7 phthalates (DMP, DEP, DPP, DiBP, BBP, DBP and DEHP) among which 5 are classified H360. Gas chromatography (GC) is also mentioned for the analysis of phthalates [18], [19], [23], [24], [25], [26], [39]. A 5% dimethylpolysiloxane column is always used for the separation of up to 7 phthalates (DnOP, DPP, DCHP, DEP, BBP, DBP, DEHP) among which only 4 are classified [19]. When mass spectrometry is used for the analysis of phthalates, a capillary column of 30 m × 0.25 mm × 0.25 μm is described, the phthalate ionization is performed by electronic impact (EI) and the detection obtained using SIM mode (m/z = 149). The sample is injected either in splitless mode [18], [25], in one-fifth [19], one-twentieth [23] split mode or in injection thermal desorption (TD) [24] using He as carrier gas. At least, a new technique based on real time detection using thin film micro-electromechanical system (MEMS) semiconductor device for rapid detection of phthalates in water and beverages has been recently published [27].

Complementary analytical methods dealing with the determination of DiDP and DiNP, phthalates proposed to be forbidden in medical devices [28], [29], were also examined. DiNP and DiDP are commonly used as plasticizers in children toys and food packaging can also be found in medical devices. Analyses are carried out by gas chromatography with flame ionization detection [30], [31] or mass detection [32], [33], [34] using characteristic ions such as m/z = 293 (for DiNP) and m/z = 307 (for DiDP) or m/z = 149 (for both compounds). As for other phthalates, split/splitless is a common injection mode, even if other injection modes such as thermal desorption [33], [34] or large-volume injection are also reported [35]. The type of chromatographic columns used (polydimethylsiloxanes, polydiphenylsiloxanes or cyanopropylpolydiméthylsiloxanes) does not appear to be essential for the determination of these phthalates. DiNP and DiDP can also be quantified using liquid chromatography with UV detection after extraction with C8 [36] or phenyl [37] SPE cartridge. The mobile phase used is often water/acetonitrile. As DiNP and DiDP consist of several isomers, depending on the nature of alcohols used for their synthesis, these phthalates are eluted as broad mass peaks [30], [33], [34], [38]. Their quantification is performed on the sum of all mass peaks. Limits of quantification obtained for these phthalates are always higher than that for other phthalates eluted as a single peak [33], [34]. Co-elutions and poor resolutions [30], [38] are commonly reported between DiNP and DiDP.

Among analytical methods found in the literature for the extraction of phthalates from plastic materials, some papers propose protocols based on stirring of the plastic at room temperature in an organic solvent such as dichloromethane [38] or acetone [36] after having cut off the material into pieces. Another paper [39] proposes an extraction process in which plastic samples are crushed into powder, after being frozen using liquid nitrogen or dry ice, and then extracted by hexane using an ultrasonic bath and stirring the content. Extraction process, based on the solubility of PVC in THF, is also described for materials derived from food packaging, children items (like toys), PVC medical devices or seals of metal lids used for the closure of glass containers. PVC is first dissolved in THF and then precipitated by adding ethanol or methanol. Phthalates contained in the supernatant solution are analysed using different chromatographic techniques [32], [40], [41]. The PVC solution in THF can also be diluted in acetonitrile and injected onto a HPLC/MS system after SPE purification [42]. Other methods describe extraction protocols similar to the technique described in the European Pharmacopoeia. PVC-based materials are introduced into ether and refluxed for 8 h using a reflux condenser. A Soxhlet extraction is also reported using either dichloromethane or cyclohexane for PVC children toys [31] and chloroform/methanol for food packaging [43]. An automatic Soxhlet process allowing the simultaneous extraction of 6 samples is described for the determination of phthalates in sludge and vegetables [44]. Procedures using special equipment to shorten the extraction process are reported. Among these procedures are supercritical fluid extraction (SFE) [31], used for the determination of phthalates in children toys, accelerated solvent extraction (ASE) with a dichloromethane/acetone mixture for inorganic materials [37] and pressurized solvent extraction (PSE) with methanol for sediments [45]. The extraction assisted by microwave (MAE) is reported as a possible extraction technique for the determination of phthalates in soil or sediment using acetone/dichloromethane [46], acetone [47] or other solvents [45]. A method allowing the extraction of plasticizers, other than phthalates, contained in PVC materials with methanol is also reported [48]. After the extraction step, the analysis can be performed either by injecting the supernatant [32], [38] or after a centrifugation step. The supernatant is then evaporated to dryness and the residue dissolved in an organic solvent possibly after a previous filtration [41], [42]. Purification using C18 SPE cartridges [18], [19], [34] or more specific ones such as Oasis® [25], [42] has also been considered.

Section snippets

Gas chromatography and mass spectrometry

All analyses are carried out on a Varian 3800 gas chromatograph interfaced with a Varian 1200 quadrupole mass spectrometer (Palo Alto, USA). The column is an Agilent HP-5MS capillary column (cross-linked poly 5% diphenyl/95% dimethylsiloxane); 30 m × 0.25 mm (i.d.) × 0.25 μm film thickness. The oven temperature is settled as follows: 100 °C ramped to 200 °C at 30 °C min−1, then to 250 °C at 3 °C min−1 held for 2.5 min, then to 270 °C at 40 °C min−1 held for 2 min and then to 320 °C at 80 °C min−1 held for 5 min. One

Method development

An analytical method for the quantification of phthalates in cosmetic products was developed and published [15]. In order to adapt this method to the quantification of phthalates in PVC medical devices, the extraction step was completely changed and additional phthalates such as DiDP or DiNP proposed to be forbidden in France in medical devices [28], [29] were added. In order to identify and quantify other plasticizers, which are commonly used in PVC medical devices such as DEHP substitute, 5

Conclusion

In 2013 different papers deal with the quantification of phthalates in plastic material using PVC as plastic but the only official method is the European pharmacopoeia (monograph 3.1.14). This official method, focused on the determination of DEHP, is based on an extraction of this phthalate with diethyl ether using a reflux condenser.

In order to have a more modern method able to determine more phthalates, a performant analytical method has been developed for the assay of 14 phthalates: 8

Acknowledgements

The authors gratefully acknowledge Nelly LASSU and Nathalie LAYOUN who contributed to the present study.

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