Qualitative Analysis of Tackifier Resins in Pressure Sensitive Adhesives Using Direct Analysis in Real Time Time-of-Flight Mass Spectrometry

Traceability of VOCs in tire inner liner by chromatography-mass spectrometry

Many parts of the vehicle cabin generate volatile organic compounds (VOCs), and some are hazardous and/or odorous to humans. In this study, VOCs in the inner liner of automobile spare tire, including raw rubbers and resins, were detected by gas chromatography-mass spectrometry (GC-MS) coupled with an extracting method of static headspace sampling (SHS). The results demonstrated that the sources of VOCs can be traced back to raw rubbers and resins: alkylphenol resins can release a large amount of 2,4,4-trimethyl-1-pentene and 2,2,4,6,6-pentamethyl-3-heptene; chlorobutyl rubber (CIIR) contained 3-methyl-pentane, and methyl-cyclopentane, and these VOCs are odorous. When alkylphenol resin and natural rubber (NR) with low VOCs were used to replace the corresponding resin and NR in the initial formulation, the total volatile organic compounds (TVOCs) in the inner liner could be reduced. We expected that the information gained from this work could provide a basic reference for the manufacture of environmental-friendly tire products.

Laser assisted sampling vs direct desorption flowing atmospheric pressure afterglow mass spectrometry of complex polymer samples: Forensic implications for pressure sensitive tape chemical analysis

Flowing atmospheric pressure afterglow (FAPA) mass spectrometry (MS) is an easy-to-use, cost-effective, and potentially portable technique that allows direct desorption/ionization from samples with little-to-no sample preparation for real-time chemical analysis. However, it has limitations regarding analytes with low desorption efficiency, such as polymers. Here, laser assisted sampling (LAS) is developed and coupled to FAPA MS to allow access to a wider range of chemical information from polymer samples. This is achieved through laser-induced pyrolysis conditions that provide a much higher degree of spatio-temporal control compared to typical pyrolysis techniques. LAS FAPA MS, together with direct desorption FAPA MS, is implemented on pressure sensitive adhesive (PSA) tape samples, which are often found at crime scenes and recovered as forensic evidence. Comparative PSA tape examination is typically performed to assess any differences in the comparison of unknown and known samples and provide an evidentiary association between suspects and crime scenes in forensic applications. PSA tape samples from several manufacturers of duct, masking, and electrical tape were analyzed from the adhesive and backing side. Direct desorption FAPA provides top-surface selectivity and the tape mass spectra are dominated by more peaks at lower m/z, many of which correspond to polymer additives. LAS gives access to sampling from all of the tape layers and the FAPA mass spectra is extended to higher m/z, while polymer fragmentation patterns are evident. Principal components analysis (PCA) was implemented to assess the ability of each technique to distinguish and categorize identified tape classes within the sampled population. The complementary nature of the resulting mass spectra from direct desorption vs LAS FAPA was evident from the PCA as different tape brands sub-sets were discriminated by each technique. The differentiation obtained by combining both methods is already competitive, or better, than conventional techniques, with the additional benefits of AMS.

Capturing hemoglobin on graphene sheet from sub-microliter whole blood for quantitative characterization by internal extractive electrospray ionization mass spectrometry

A disposable blood sampler, which is consisted of a sub-microliter whole blood collector and a graphene filter, loading graphene sheet to selectively capture hemoglobin from sub-microliter whole blood, was developed for both qualitative and quantitative characterization hemoglobin by internal extractive electrospray ionization mass spectrometry (iEESI-MS). The blood collector was elegantly fabricated in syringe-like fashion for precisely sampling tiny amounts (1.0 μL - 2%) of whole blood, which was immediately diluted by water inside the syringe and was then pressed through the graphene filter placed between the waste outlet and the syringe reservoir to capture the hemoglobin in the blood sample. Then the graphene with hemoglobin was directly eluted by a charged (+2.5 kV) solution (mathanol/water/formic acid, 48/48/4, v/v/v) to produce the hemoglobin ions for mass spectrometric analysis. Low detection-of-limit (19.3 mg L^-1 (89.5 picomol)), acceptable linear response range (300-1500 mg L^-1, R² = 0.998), relative standard deviation (0.5-6.5%, n = 3), low sample consumption (≤1.0 μL) and a relatively high speed (≤4 min per sample, including the sample loading) were achieved, demonstrating that the graphene based iEESI-MS was an alternative choice for direct detection of hemoglobin in whole blood with minimal sample consumption.

Screening of additives and other chemicals in polyurethanes by direct analysis in real time mass spectrometry (DART-MS)

Direct analysis in real time mass spectrometry (DART-MS) was used to characterize commercial polyurethane (PUR) samples without sample pretreatment. More than 50 substances, such as catalysts, stabilizers, antioxidants, flame retardants, plasticizers, chain extenders, chain terminators, polyols, solvents, degradation products and contaminants, a few of them presumably toxic, were detected and identified in 18 PUR items. The identification of 16 compounds was further confirmed by DART MS/MS experiments. Catalysts were the largest class of compounds detected in the PURs by DART-MS. In each of the 18 PUR samples, at least one catalyst residue was identified. In addition, DART-MS was able to detect the migration of hazardous chemicals from the PURs to other objects. The collision-induced dissociation (CID) properties of two PUR catalysts, such as the protonated bis[2-(dimethylamino)ethyl] ether (DMAEE) and the protonated 2,2-dimorpholinodiethylether (DMDEE), as well as those of two PUR antioxidants (Antioxidant 1135 and Antioxidant 1076), were explored.

Ambient Characterization of Synthetic Fibers by Laser Ablation Electrospray Ionization Mass Spectrometry

Direct analysis of synthetic fibers under ambient conditions is highly desired to identify the polymer, the finishes applied and irregularities that may compromise its performance and value. In this paper, laser ablation electrospray ionization ion mobility time-of-flight mass spectrometry (LAESI-IMS-TOF-MS) was used for the analysis of synthetic polymers and fibers. The key to this analysis was the absorption of laser light by aliphatic and aromatic nitrogen functionalities in the polymers. Analysis of polyamide (PA) 6, 46, 66, and 12 pellets and PA 6, 66, polyaramid and M5 fibers yielded characteristic fragment ions without any sample pretreatment, enabling their unambiguous identification. Synthetic fibers are, in addition, commonly covered with a surface layer for improved adhesion and processing. The same setup, but operated in a transient infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) mode, allowed the detailed characterization of the fiber finish layer and the underlying polymer. Differences in finish layer distribution may cause variations in local properties of synthetic fibers. Here we also show the feasibility of mass spectrometry imaging (MSI) of the distribution of a finish layer on the synthetic fiber and the successful detection of local surface defects.

Impact of immobilization support on colorimetric microarrays performances

We report here a comparison of support materials for colorimetric hybridization assays on microarrays. Four surfaces with various chemistries and architectures (roughness and porosity) were evaluated: (i) bare and (ii) activated polystyrene surfaces classically used for ELISA; (iii) a double-sided adhesive support; and (iv) a porous nitrocellulose/cellulose acetate membrane. Each substrate was functionalized with a microarray of probes and subjected to an enzymatic colorimetric DNA hybridization test. Tests were carried out in a 96-well assembly suitable for automated high-throughput analysis. Colorimetry results, microscopy observations and a chemiluminescence study showed that the test efficiency not only depends on the surface probe density but that the capacity of the material to retain the colored enzymatic product is also a critical parameter. All parameters being considered, the adhesive coated surface proposes the best surface properties for efficient colorimetric microarrays.