Non-target screening of (semi-)volatiles in food-grade polymers by comparison of atmospheric pressure gas chromatography quadrupole time-of-flight and electron ionization mass spectrometry

Utilization of Negative Chemical Ionization to Expand Nontargeted Screening of Halogenated Organics in Great Lakes Top Predator Fish

Nontargeted screening (NTS) of halogenated contaminants in biota is part of the routine monitoring of the Great Lakes ecosystem. NTS can give insight into new chemicals with possible persistent, bioaccumulative, and toxic (PBT) properties and help quantify known PBT's degradation and transformation products. The most common ionization technique for NTS is electron impact ionization (EI) due to the consistent and easily standardized fragmentation patterns. This research uses electron capture negative ionization (ECNI) as a complementary technique to broaden the range of halogenated contaminants detected in the Great Lakes. ECNI has higher sensitivity and selectivity to halogenated compounds compared to EI. GC × GC-HR-ToF MS with a multimode ion source (MMS) offers consecutive runs in EI and ECNI modes using the same chromatographic setup, facilitating retention time alignment. The exact mass measurements help in identifying compounds found only in ECNI. A total of 85 novel halogenated features were detected, 78% of which were detected only in ECNI. Only 9% of the features were detected in both modes, indicating that ECNI is a necessary complementary technique for NTS of halogenated features.

Designing safe recycled high-density polyethylene (HDPE) for child toys

New high-density polyethylene (HDPE) manufactured from different percentage of post-consumer recycled HDPE milk bottles was studied through two static and dynamic migration tests using saliva simulant to assess the potential hazard to children. Sixty-nine compounds were identified, including several additives used in PE synthesis such as alkanes, alkenes, antioxidants and plasticizers as well as non-intentionally added substances (NIAS) like degradation products such as 2,6-di-tert-butyl-1,4-benzoquinone, 2,4-di-tert-butylphenol, phenol, 2,5-bis(1,1-dimethylethyl)-, 3,5-di-tert-butyl-4-hydroxybenzaldehyde, and 3,5-di-tert-butyl-4-hydroxyacetophenone, or various residues from flavoring agents, cleaning products and essential oils. Some of these compounds as the isomers p and o t-butylcyclohexyl acetate, 3-Octanol, 3,7-dimethyl- and thujanol acetate (3-) pose a potential risk to children, as their concentrations exceed the recommended Cramer values for high percentages of recycling. This suggests improving recycling processes by incorporating advanced cleaning to remove residual products and contaminants.

Comprehensive study of retention influencing gas chromatographic parameters affecting linear retention indices

Retention in gas chromatographic systems has a central role in the identification of compounds even if detectors providing spectral information are used. But linear retention indices (LRI) of a single compound originating from multiple sources tend to vary greatly, probably due to differences in the experimental settings of the determinations. The effect of gas chromatographic parameters on LRI has been investigated using 41 compounds - previously identified from food contact plastics - and n-alkanes (n-C7-n-C40) used as reference series. As the reproducibility of LRIs under the same conditions is generally very good, the smallest changes in the settings often caused statistically significant, though irrelevant changes in the LRI values. Therefore, a multicriterial scoring-ranking system has been worked out to highlight the LRI value differences. Our results highlight that column length, heating rate, and film thickness can all be the reasons of the varying published LRI values. We also demonstrated that for the reproduction of LRI data, the chemistry (and not simply the polarity) of the stationary phase is crucial.

Recent Advances in Non-Targeted Screening of Compounds in Plastic-Based/Paper-Based Food Contact Materials

Ensuring the safety of food contact materials has become a pressing concern in recent times. However, detecting hazardous compounds in such materials can be a complex task, and traditional screening methods may not be sufficient. Non-targeted screening technologies can provide comprehensive information on all detectable compounds, thereby supporting the identification, detection, and risk assessment of food contact materials. Nonetheless, the non-targeted screening of food contact materials remains a challenging issue. This paper presents a detailed review of non-targeted screening technologies relying on high-resolution mass spectrometry for plastic-based and paper-based food contact materials over the past five years. Methods of extracting, separating, concentrating, and enriching compounds, as well as migration experiments related to non-targeted screening, are examined in detail. Furthermore, instruments and devices of high-resolution mass spectrometry used in non-targeted screening technologies for food contact materials are discussed and summarized. The research findings aim to provide a theoretical basis and practical reference for the risk management of food contact materials and the development of relevant regulations and standards.

Elucidation of Non-Intentionally Added Substances from Plant Fiber/Plastic Composites by UPLC-QTOF/MS

Plant fiber/plastic composites (PPCs) have been widely used in food contact materials (FCMs) for many benefits, such as their claimed better environmental footprint compared to conventional plastics. However, their safety is still not fully understood and must be comprehensively evaluated. Non-volatiles extracted from six PPCs with different plant fibers and polymer matrices were characterized by employing ultra-high-performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry in combination with various spectral libraries and manual elucidation, taking into account spectral similarity and characteristic product ions. A total of 115 compounds were tentatively identified, 50 of which were oligomers or their derivatives from the sample with polylactic acid (PLA) and polybutylene adipate terephthalate (PBAT) as the polymer matrix, and some of them were Cramer rules class III substances based on the threshold of toxicological concern (TTC). Seven reaction products between PLA and PBAT monomers, as well as four derivatives of melamine, were elucidated and well detailed for the first time. In addition, bisphenol S was detected in all samples even though its origin remains to be further explored. Isoprothiolane, as an insecticide and fungicide used to control a range of rice pests, was identified in the sample with rice husk as fillers, experimentally confirming the presence of agrochemicals in samples containing plant fibers.

Benefits of Ion Mobility Separation in GC-APCI-HRMS Screening: From the Construction of a CCS Library to the Application to Real-World Samples

The performance of gas chromatography (GC) combined with the improved identification properties of ion mobility separation coupled to high-resolution mass spectrometry (IMS-HRMS) is presented as a promising approach for the monitoring of (semi)volatile compounds in complex matrices. The soft ionization promoted by an atmospheric pressure chemical ionization (APCI) source designed for GC preserves the molecular and/or quasi-molecular ion information enabling a rapid, sensitive, and efficient wide-scope screening. Additionally, ion mobility separation (IMS) separates species of interest from coeluting matrix interferences and/or resolves isomers based on their charge, shape, and size, making IMS-derived collision cross section (CCS) a robust and matrix-independent parameter comparable between instruments. In this way, GC-APCI-IMS-HRMS becomes a powerful approach for both target and suspect screening due to the improvements in (tentative) identifications. In this work, mobility data for 264 relevant multiclass organic pollutants in environmental and food-safety fields were collected by coupling GC-APCI with IMS-HRMS, generating CCS information for molecular ion and/or protonated molecules and some in-source fragments. The identification power of GC-APCI-IMS-HRMS for the studied compounds was assessed in complex-matrix samples, including fish feed extracts, surface waters, and different fruit and vegetable samples.

Guidance in selecting analytical techniques for identification and quantification of non-intentionally added substances (NIAS) in food contact materials (FCMS)

There are numerous approaches and methodologies for assessing the identity and quantities of non-intentionally added substances (NIAS) in food contact materials (FCMs). They can give different results and it can be difficult to make meaningful comparisons. The initial approach was to attempt to prepare a prescriptive methodology but as this proved impossible; this paper develops guidelines that need to be taken into consideration when assessing NIAS. Different approaches to analysing NIAS in FCMs are reviewed and compared. The approaches for preparing the sample for analysis, recommended procedures for screening, identification, and quantification of NIAS as well as the reporting requirements are outlined. Different analytical equipment and procedures are compared. Limitations of today's capabilities are raised along with some research needs.

Chemical Characterization and Non-targeted Analysis of Medical Device Extracts: A Review of Current Approaches, Gaps, and Emerging Practices

The developers of medical devices evaluate the biocompatibility of their device prior to FDA's review and subsequent introduction to the market. Chemical characterization, described in ISO 10993-18:2020, can generate information for toxicological risk assessment and is an alternative approach for addressing some biocompatibility end points (e.g., systemic toxicity, genotoxicity, carcinogenicity, reproductive/developmental toxicity) that can reduce the time and cost of testing and the need for animal testing. Additionally, chemical characterization can be used to determine whether modifications to the materials and manufacturing processes alter the chemistry of a patient-contacting device to an extent that could impact device safety. Extractables testing is one approach to chemical characterization that employs combinations of non-targeted analysis, non-targeted screening, and/or targeted analysis to establish the identities and quantities of the various chemical constituents that can be released from a device. Due to the difficulty in obtaining a priori information on all the constituents in finished devices, information generation strategies in the form of analytical chemistry testing are often used. Identified and quantified extractables are then assessed using toxicological risk assessment approaches to determine if reported quantities are sufficiently low to overcome the need for further chemical analysis, biological evaluation of select end points, or risk control. For extractables studies to be useful as a screening tool, comprehensive and reliable non-targeted methods are needed. Although non-targeted methods have been adopted by many laboratories, they are laboratory-specific and require expensive analytical instruments and advanced technical expertise to perform. In this Perspective, we describe the elements of extractables studies and provide an overview of the current practices, identified gaps, and emerging practices that may be adopted on a wider scale in the future. This Perspective is outlined according to the steps of an extractables study: information gathering, extraction, extract sample processing, system selection, qualification, quantification, and identification.

Gas Chromatography Coupled to Atmospheric Pressure Chemical Ionization High-Resolution Mass Spectrometry for Metabolite Fingerprinting of Grape (Vitis vinifera L) Berry

This chapter describes the application of atmospheric pressure chemical ionization in conjunction with gas chromatography (APGC) coupled to high-resolution mass spectrometry for profiling metabolites in plant and fruit extracts. The APGC technique yields molecular ions and limited fragmentation of volatile or derivatized compounds. The data-independent acquisition mode, MS^E, was used for measuring precursor and fragment ions with high resolution using a quadrupole ion mobility time-of-flight mass spectrometry system. We demonstrate the importance of acquiring accurate mass information in conjunction with accurate mass fragment ions for efficient database searching and compound assignments with high confidence. We demonstrate the application of APGC-MS^E for obtaining metabolite data for grape berry extracts after derivatization.

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.

Fabric phase sorptive extraction for specific migration analysis of oligomers from biopolymers

Oligomers are potential migrants from polymers or biopolymers intended to food packaging and they have to be under control. In order to comply with European regulation 10/2011, their concentration in migration must be below 0.01 μg g^-1. In this work, fabric phase sorptive extraction (FPSE) was explored as an effective method for extraction and pre-concentration of oligomers migrated from a blend PLA-polyester material. Both food simulant B (3% acetic acid) and juice, as real food, were used for migration experiments. The parameters of FPSE were optimized and the analysis was done by UHPLC-QTOF and UHPLC-QqQ. A total of 21 oligomers were identified, 9 of them coming from PLA and 12 oligomers from the polyester part. These oligomers were formed by adipic acid (AA), phthalic acid (PA) and/or butanediol (BD), ten were cyclic and 11 were linear molecules. Using the optimized FPSE procedure in 3% acetic acid as food simulant, it was possible to identify 3 new compounds that were not detected by direct injection of the simulant into UHPLC-QTOF. In addition, 2 extra compounds, cyclic PA-BD₄-AA₃ and cyclic PA₂-BD₃-AA, were only identified in juice samples after FPSE extraction. Besides, in order to quantify the compounds identified, an isolation procedure for PLA oligomers was carried out. Two oligomers were isolated: cyclic (LA)₆ and linear HO-(LA)₄-H, both with a purity higher than 90% (LA: lactic acid). The highest concentration value was found for the cyclic oligomer [AA-BD]₂, that showed 22.63 μg g^-1 in 3% acetic acid and 19.64 μg g^-1 in juice. The concentration of the total amount of remaining oligomers was below 7.56 μg g^-1 in 3% acetic acid as well as in juice.

The migration of NIAS from ethylene-vinyl acetate corks and their identification using gas chromatography mass spectrometry and liquid chromatography ion mobility quadrupole time-of-flight mass spectrometry

An exhaustive migration study of eight corks, made of ethylene-vinyl acetate, was carried out to identify any non-volatile and volatile compounds using an untargeted approach. The challenge associated with the structural elucidation of unknowns was undertaken using both ultra-high-performance liquid chromatography coupled to an ion-mobility separation quadrupole-time of flight mass spectrometer and gas chromatography mass spectrometry. A total of fifty compounds were observed to migrate from the corks, and among these additives such as antioxidants (Butyl 4-hydroxybenzoate, Irganox 1010, Irganox 1075, Irgafos 168 and BHT) or lubricants (EBO and octadecanamide, N,N'-1,2-ethanediylbis-) were identified. A high proportion (84%) of the detected compounds was non-intentionally added substances (NIAS), and included several cyclic oligomers with different chain sequences. NIAS, such as 2,6-bis(1,1-dimethylethyl)-4-ethyl and 7,9-ditert-butyl-1-oxaspiro[4.5]deca-6,9-diene-2,8-dione, break-down products, including hexa-, hepta- and nonadecanamide, N,N'-1,2-ethanediylbis-, and oxidation products were also identified. One cork was found to be unsuitable for use as a food contact material.

Identification of Potential Extractablesand Leachables in Cosmetic Plastic Packagingby Microchambers-Thermal Extraction and Pyrolysis-Gas Chromatography-Mass Spectrometry

Most container-content interaction studies are carried out through migration tests on end products or simulants involving generally toxic solvents. This study was conducted with the aim of identifying potential leachables from materials used in cosmetic plastic packaging by using two approaches based on solvent-free extraction, i.e., solid-phase microextraction sampling and pyrolyzer/thermal desorption coupled with gas chromatography mass spectrometry. Volatile and semi-volatile intentionally and non-intentionally added substances were detected in seven packaging samples made of polypropylene, polyethylene, and styrene-acrylonitrile copolymer. Thirty-five compounds related to the polymers industry or packaging industry were identified, among them phthalates, alkanes, styrene, and cyanide derivates including degradation products, impurities, additives, plasticizers, and monomers. All except eight belong to the Cramer class I. These thermodesorption techniques are complementary to those used for migration tests.

Analytical Approaches for Analysis of Safety of Modern Food Packaging: A Review

Nowadays, food packaging is a crucial tool for preserving food quality and has become an inseparable part of our daily life. Strong consumer demand and market trends enforce more advanced and creative forms of food packaging. New packaging development requires safety evaluations that always implicate the application of complex analytical methods. The present work reviews the development and application of new analytical methods for detection of possible food contaminants from the packaging origin on the quality and safety of fresh food. Among food contaminants migrants, set-off migrants from printing inks, polymer degradation products, and aromatic volatile compounds can be found that may compromise the safety and organoleptic properties of food. The list of possible chemical migrants is very wide and includes antioxidants, antimicrobials, intentionally added substances (IAS), non-intentionally added substances (NIAS), monomers, oligomers, and nanoparticles. All this information collected prior to the analysis will influence the type of analyzing samples and molecules (analytes) and therefore the selection of a convenient analytical method. Different analytical strategies will be discussed, including techniques for direct polymer analysis.