Analysis of brominated flame retardants and their derivatives by atmospheric pressure chemical ionization using gas chromatography coupled to tandem quadrupole mass spectrometry

Direct Mass Spectrometric Analysis of Brominated Flame Retardants in Synthetic Polymers

Brominated flame retardants (BFRs) are persistent organic pollutants that pose a major threat to the environment. In this study, a direct insertion probe (DIP) coupled with atmospheric pressure chemical ionization (APCI) quadrupole time-of-flight mass spectrometry (QTOF-MS) was used to characterize additives, especially BFRs, from solid polymer samples with minimal sample preparation. A temperature-programmed DIP analysis, from 150 to 450 °C within 10 min, was utilized to achieve temporal separation of analytes based on their boiling or degradation temperatures, thereby facilitating their easier identification within a single run. Studied BFRs showed different behaviors during the analysis: decabromodiphenyl ether and tetrabromobisphenol A were found to be stable within the studied temperature range, while hexabromocyclododecane already started to debrominate. Our study showed that the DIP-APCI-MS method suited well for the direct qualitative identification of BFRs from polymer matrices. Furthermore, by optimizing the sampling procedure with cryogenic grinding, even quantitative analysis could be performed. The DIP measurements also provided important information about the composition of polymer matrices, including the identification of the comonomers present. Overall, DIP-APCI QTOF-MS was found to be an excellent tool for the compositional analysis of plastic samples. Developing rapid and reliable analysis methods can pave the way for more efficient plastic recycling and the safer use of plastic recyclates.

Selection of recycled waste plastic for incorporation in sustainable asphalt pavements: A novel multi-criteria screening tool based on 31 sources of plastic

This study investigated the suitability of 31 recycled waste plastic samples obtained from 15 major recycling companies across Australia and New Zealand to be used as bitumen/asphalt modifiers. The plastics have been selected to be representative of recycled waste plastic around Australia and New Zealand. The recycled waste plastics belonged to either the post-industrial or post-consumer collection scheme. A new classification scheme was developed to rank each recycled waste plastic based on their chemical and physical properties against those of bitumen/asphalt. Specifically, density, polarity, melting point, solubility and melt flow index of the samples as well as the presence of contaminants, fillers and additives were analyzed for each recycled waste plastic material and their virgin counterpart. These 8 properties were used to rank various sources of recycled low-density poly(ethylene), linear low-density poly(ethylene), high density poly(ethylene) and poly(propylene) in addition to commingled plastics based on their suitability for bitumen modification (wet method). The modification of asphalt via replacement of virgin quarry aggregate with plastic aggregate (dry method) by recycled acrylonitrile butadiene styrene and poly(ethylene terephthalate) was also assessed by considering four criteria of purity, polarity, recycling contamination and hazardous additives. This new multi-criterion ranking approach revealed that low-density and linear low-density poly(ethylene) and acrylonitrile butadiene styrene and poly(ethylene terephthalate) should be preferentially used as bitumen/asphalt modifiers. This tool has been developed for recycling companies and bitumen/asphalt contractors to determine the suitability of recycled waste plastics within asphalt roads by a series of experimental techniques.

Nontargeted Screening Using Gas Chromatography-Atmospheric Pressure Ionization Mass Spectrometry: Recent Trends and Emerging Potential

Gas chromatography–high-resolution mass spectrometry (GC–HRMS) is a powerful nontargeted screening technique that promises to accelerate the identification of environmental pollutants. Currently, most GC–HRMS instruments are equipped with electron ionization (EI), but atmospheric pressure ionization (API) ion sources have attracted renewed interest because: (i) collisional cooling at atmospheric pressure minimizes fragmentation, resulting in an increased yield of molecular ions for elemental composition determination and improved detection limits; (ii) a wide range of sophisticated tandem (ion mobility) mass spectrometers can be easily adapted for operation with GC–API; and (iii) the conditions of an atmospheric pressure ion source can promote structure diagnostic ion–molecule reactions that are otherwise difficult to perform using conventional GC–MS instrumentation. This literature review addresses the merits of GC–API for nontargeted screening while summarizing recent applications using various GC–API techniques. One perceived drawback of GC–API is the paucity of spectral libraries that can be used to guide structure elucidation. Herein, novel data acquisition, deconvolution and spectral prediction tools will be reviewed. With continued development, it is anticipated that API may eventually supplant EI as the de facto GC–MS ion source used to identify unknowns.

Naturally occurring organobromine compounds (OBCs) including polybrominated dibenzo-p-dioxins in the marine sponge Hyrtios proteus from The Bahamas

Halogenated natural products (HNPs) were identified from organic extracts of the marine sponge Hyrtios proteus from The Bahamas using gas chromatography with electron capture negative ion mass spectrometry and non-targeted gas chromatography with electron ionization mass spectrometry. The HNPs found have similar properties to anthropogenic persistent organic pollutants (POPs). Two ortho-methoxy brominated diphenyl ethers (MeO-BDEs) 2'-MeO-BDE 68 and 6-MeO-BDE 47 were the most abundant compounds. Fourteen other MeO-BDEs were detected along with several polybrominated dibenzo-p-dioxins (PBDDs) (1,3,7-triBDD, 1,3,6,8-tetraBDD and 1,3,7,9-tetraBDD) and MeO-PBDDs. Further analysis of a higher trophic level octopus (Octopus maya) from the same FAO fishing area showed that the major HNPs detected in Hyrtios proteus were also predominant. Moreover, HNPs were more than 30-fold higher in abundance than the major POPs in the octopus, i.e., polychlorinated biphenyls. Hence, Caribbean marine organisms, including those potentially used for food, harbor relatively high concentrations of HNPs.

Brominated flame retardants (BFRs) in contaminated food contact articles: identification using DART-HRMS and GC-MS

Any food contact material (FCM) must be approved by the US FDA as being compliant with Title 21 of the Code of Federal regulations Parts 170-199, and/or obtain a non-objection letter through the Food Contact Notification Process, before being placed into the United States market. In the past years, several scientific articles identified FCM or more specifically, food contact articles (FCAs), which were contaminated with brominated flame retardants (BFRs) in the European Union. Prior research has suggested the source of BFR contamination was likely poorly recycled plastics containing waste electrical and electronic equipment (WEEE). We conducted a retail survey to evaluate the presence of BFR-contaminated reusable FCA in the US market. Using a Direct Analysis in Real Time ionisation High-Resolution Mass Spectrometry (DART-HRMS) screening technique and extraction gas chromatography-mass spectrometry (GC-MS) confirmation we were able to identify BFRs present in retail FCAs. Among non-targeted retail samples, 4 of 49 reusable FCAs contained 1-4 BFRs each. The identified BFRs, found in greatest estimated concentrations, were 2,4,6-tribromophenol (TBP), 3,3',5,5'-tetrabromobisphenol A (TBBPA), hexabromocyclododecane (HBCD), decabromodiphenylethane (DBDPE) and decabromodiphenylether (BDE-209). A second targeted FCA sampling (n = 28) confirmed these BFRs persisted in similar articles. Combined sample sets (n = 77) estimated DART false-positive/negative incidences of 5% & 4%, respectively, for BFR screening of FCAs. Because the presence of BFRs in some contaminated FCAs has been demonstrated and since these compounds are possible migrants into food, further studies are warranted. In order to estimate the potential exposure of the identified BFRs and conduct corresponding risk assessments, the next and logical step will be to study the mass transfer of BFRs from the contaminated FCM into food simulants and food.

Persistent Organic Pollutants in Food: Contamination Sources, Health Effects and Detection Methods

Persistent organic pollutants (POPs) present in foods have been a major concern for food safety due to their persistence and toxic effects. To ensure food safety and protect human health from POPs, it is critical to achieve a better understanding of POP pathways into food and develop strategies to reduce human exposure. POPs could present in food in the raw stages, transferred from the environment or artificially introduced during food preparation steps. Exposure to these pollutants may cause various health problems such as endocrine disruption, cardiovascular diseases, cancers, diabetes, birth defects, and dysfunctional immune and reproductive systems. This review describes potential sources of POP food contamination, analytical approaches to measure POP levels in food and efforts to control food contamination with POPs.

Evaluation of gas chromatography-atmospheric pressure chemical ionization tandem mass spectrometry as an alternative to gas chromatography tandem mass spectrometry for the determination of polychlorinated biphenyls and polybrominated diphenyl ethers

A method for the analysis of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in serum was developed using gas chromatography coupled to tandem mass spectrometry with atmospheric pressure chemical ionization (GC-APCI-MS/MS). The ionization and fragmentation performance of APCI were evaluated and compared with those of electron ionization (EI). In contrast to extensive fragmentation caused by EI with high energy, soft ionization achieved by APCI produced mass spectra dominated by molecular ions from the first stage of MS analysis. Better sensitivity and selectivity achieved by the GC-APCI-MS/MS method allowed to analyze serum samples with a low volume (100 μL). The limits of detection (LODs) ranged from 0.067 to 14 pg/mL for the analysis in serum samples. The developed method was evaluated at three spiking levels (0.05, 0.5 and 5 ng/mL for PCBs), showing good recoveries and repeatability. The recoveries ranged from 74.0% to 130.5%, and the relative standard deviations (RSDs) were less than 20%, for all analytes. The determination of PCBs and PBDEs in the human serum samples by GC-APCI-MS/MS was compared with gas chromatography-tandem mass spectrometry with EI (GC-EI-MS/MS). BDE-99 and BDE-100 were successfully quantified by GC-APCI-MS/MS, while these two PBDE congeners were not detected by GC-EI-MS/MS. The GC-APCI-MS/MS method had a clear advantage when analyzing compounds at low levels.

Temporal trends of decabromodiphenyl ether and emerging brominated flame retardants in dust, air and window surfaces of newly built low-energy preschools

The envelope of low-energy buildings is generally constructed with significant amounts of plastics, sealants and insulation materials that are known to contain various chemical additives to improve specific functionalities. A commonly used group of additives are flame retardants to prevent the spread of fire. In this study, decabromodiphenyl ether (BDE-209) and fourteen emerging brominated flame retardants (BFRs) were analyzed in indoor dust, air and on the window surface of newly built low-energy preschools to study their occurrence and distribution. BDE-209 and decabromodiphenyl ethane (DBDPE) were frequently detected in the indoor dust (BDE-209: <4.1-1200 ng/g, DBDPE: <2.2-420 ng/g) and on window surfaces (BDE-209: <1000-20 000 pg/m² , DBDPE: <34-5900 pg/m² ) while the other thirteen BFRs were found in low levels (dust: <0.0020-5.2 ng/g, window surface: 0.0078-35 pg/m² ). In addition, the detection frequencies of BFRs in the indoor air were low in all preschools. Interestingly, the dust levels of BDE-209 and DBDPE were found to be lower in the environmentally certified low-energy preschools, which could be attributed to stricter requirements on the chemical content in building materials and products. However, an increase of some BFR levels in dust was observed which could imply continuous emissions or introduction of new sources.

Fast gas chromatography-atmospheric pressure (photo)ionization mass spectrometry of polybrominated diphenylether flame retardants

Gas chromatography (GC) and mass spectrometry (MS) are powerful, complementary techniques for the analysis of environmental toxicants. Currently, most GC-MS instruments employ electron ionization under vacuum, but the concept of coupling GC to atmospheric pressure ionization (API) is attracting revitalized interest. API conditions are inherently compatible with a wide range of ionization techniques as well high carrier gas flows that enable fast GC separations. This study reports on the application of atmospheric pressure chemical ionization (APCI) and a custom-built photoionization (APPI) source for the GC-MS analysis of polybrominated diphenyl ethers (PBDEs), a ubiquitous class of flame retardants. Photoionization of PBDEs resulted in the abundant formation of molecular ions M^•+ with very little fragmentation. Some photo-oxidation was observed, which differentiated critical BDE isomers. Formation of protonated molecules [M+H]⁺ did not occur in GC-APPI because the ionization energy of H₂O (clusters) exceeds the energy of the ionizing photons. Avoiding mixed-mode ionization is a major advantage of APPI over APCI, which requires careful control of the source conditions. A fast GC-API-MS method was developed using helium and nitrogen carrier gases that provides good separation of critical isomers (BDE-49/71) and elution of BDE 209 in less than 7 min (with He) and 15 min (with N₂). It will be shown that the GC-APPI and GC-APCI methods match the sensitivity and improve upon the selectivity and throughput of established methods for the analysis of PBDEs using standard reference materials (NIST SRM 1944 and SRM 2585) and selected environmental samples.

Fast and environmental-friendly methods for the determination of polybrominated diphenyl ethers and their metabolites in fish tissues and feed

Environmental-friendly, cost-effective and fast methods were developed and validated for the analysis of seven PolyBrominated Diphenyl Ethers (PBDEs) and eight methoxylated PBDEs (MeO-PBDEs) in three distinct seafood matrices (muscle, liver and plasma) and feed using a Quick, Easy, Cheap, Efficient, Rugged and Safe (QuEChERS) extraction approach for solid samples and a Dispersive Liquid-Liquid Microextraction method (DLLME) for plasma. Instrumental analyses were performed with gas chromatography coupled to triple quadrupole mass spectrometry using electron impact source (GC-EI-MS/MS) and negative ion chemical ionization (GC-NICI-MS) to assess BDE-209. Statistical validation showed recoveries for all target substances near 100% with average Relative Standard Deviation (RSD) lower than 9% and recovery standards higher than 65% (average RSD below 20%). Average calculated Method Detection Limits (MDLs) were lower than 65 pg·g^-1 wet weight (WW) for muscle, 5.35 ng·g^-1 WW for liver, 4.50 ng·g^-1 WW for feed, and 0.60 ng·mL^-1 for plasma samples. Quality assurance and quality control practices were comprehensively described. Methods scored high in an analytical Eco-scale, thus being classified as "an excellent green analysis". Finally, real seafood samples collected in local markets and local fishermen were analyzed. Positive samples presented both PBDEs and MeO-PBDEs in safe amounts (0.28-125.80 ng·g^-1 WW) for human consumption.

Steroid hormone profiling in human breast adipose tissue using semi-automated purification and highly sensitive determination of estrogens by GC-APCI-MS/MS

Body mass index is a known breast cancer risk factor due to, among other mechanisms, adipose-derived hormones. We developed a method for steroid hormone profiling in adipose tissue to evaluate healthy tissue around the tumor and define new biomarkers for cancer development. A semi-automated sample preparation method based on gel permeation chromatography and subsequent derivatization with trimethylsilyl (TMS) is presented. Progestagens and androgens were determined by GC-EI-MS/MS (LOQ 0.5 to 10 ng/g lipids). For estrogen measurement, a highly sensitive GC-APCI-MS/MS method was developed to reach the required lower limits of detection (0.05 to 0.1 ng/g lipids in matrix, 100-200 fg on column for pure standards). The combination of the two methods allows the screening of 27 androgens and progestagens and 4 estrogens from a single sample. Good accuracies and repeatabilities were achieved for each compound class at their respective limit of detection. The method was applied to determine steroid hormone profiles in adipose tissue of 51 patients, collected both at proximity and distant to the tumor. Out of the 31 tested steroid hormones, 14 compounds were detected in human samples. Pregnenolone, 17-hydroxypregnenolone, dehydroepiandrosterone (DHEA), and androstendione accounted together for 80% of the observed steroid hormone profiles, whereas the estrogens accounted for only 1%. These profiles did not differ based on sampling location, except for ß-estradiol; steroid hormone conversions from androgens to estrogens that potentially take place in adipose or tumoral tissue might not be detectable due a factor 100 difference in concentration of for example DHEA and ß-estradiol. Graphical Abstract Schematic overview of the determination of steroid hormones and metabolites in adipose tissue in proximity and distal to the tumor.