An official website of the United States government
Fatty acid-based ignitable liquids (ILs), such as biodiesels and bio-based lighter fluids, represent a growing class of accelerants with limited forensic characterization. In this study, we applied gas chromatography–mass spectrometry (GC–MS) and direct analysis in real time mass spectrometry (DART–MS) to analyze plant oil-derived IL residues on wood and fabric substrates. ILs were prepared from ten different plant oils, subjected to burning, and extracted from fire debris using the ASTM E1412 activated charcoal method. GC–MS analysis resolved characteristic fatty acid methyl esters (FAMEs) and identified diagnostic fragment ions (m/z 55, 67, 74, 79). The fragmentation patterns of unsaturated and saturated FAMEs were systematically examined and compared against experimental data and reference spectra from online databases, demonstrating strong agreement and validating the reliability of these ion ratios as qualitative indicators of FAME saturation. DART–MS enabled rapid confirmation of major unsaturated FAMEs through the detection of protonated molecular ions, offering complementary identification without chromatographic separation. Chemometric analysis using principal component analysis (PCA) and analysis of variance-PCA revealed that FAME profiles were strongly dependent on the IL sources and remained reliable across replicate preparations and synthesis conditions, while substrate and combustion effects were mitigated using targeted ion extraction. These findings demonstrate the practical casework relevance of combining GC–MS and DART–MS for the detection and classification of fatty acid–based ILs in fire debris, providing robust chemical evidence to support arson investigations and to guide the inclusion of these emerging accelerants in forensic ignitable-liquid classification schemes.
more »
« less
NMR and GPC Analysis of Alkyd Resins: Influence of Synthesis Method, Vegetable Oil and Polyol Content
Alkyd resins are oil-based polymers that have been widely used for generations in the surface coating industry and beyond. Characterization of these resins is of high importance to understand the influence of its components on its behavior, compatibility with other resins, and final quality to ensure high durability. Here, NMR spectroscopy and GPC were used for characterizing differences in the chemical structure, molecular distribution, and dispersity between oil-based and fatty acid-based alkyd polymers made from sacha inchi and linseed oils. Sancha inchi (Plukentia volubilis L.) is a fruit-bearing plant native to South America and the Caribbean, and has a rich unsaturated fatty acid content. The effect of vegetable oil and polyol selection on the synthesis of alkyd resins for coating applications was analyzed. The influence of two different synthesis methods, monoglyceride and fatty acid processes, was also compared. Important structural differences were observed using NMR: one-dimensional spectra revealed the degree of unsaturated fatty acid chains along the polyester backbone, whereas, 2D NMR experiments facilitated chemical shift assignments of all signals. GPC analysis suggested that alkyd resins with homogeneous and high molecular weights can be obtained with the fatty acid process, and that resins containing pentaerythritol may have uniform chain lengths.
more »
« less
- Award ID(s):
- 1921854
- PAR ID:
- 10491943
- Publisher / Repository:
- MDPI
- Date Published:
- Journal Name:
- Polymers
- Volume:
- 15
- Issue:
- 9
- ISSN:
- 2073-4360
- Page Range / eLocation ID:
- 1993
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Significant strides in the development of non-isocyanate polyurethane (NIPU) have been made in the coatings industry. Aligned with green chemistry principles, this study explores the use of bio-based, low volatile organic compounds and fast-curing waterborne NIPU for coating applications. The linseed oilbased cyclic carbonate was synthesized via a thiol–ene click reaction and was followed by an esterification reaction directly from linseed oil. In this structure, the cyclic carbonates are introduced as pendant functional groups to accelerate the curing. Next, a series of linseed oil-based waterborne NIPUs were synthesized and developed from the linseed oil-based cyclic carbonate, a bio-based fatty acid diamine, and an internal dispersion agent. Different formulations of the linseed oil-based NIPU coatings were designed by varying the internal dispersion agent content and urethane content, and a solvent-borne NIPU was included in the study for comparison purposes. The NIPU coatings with different formulations achieved a broad range of thermal stabilities, viscoelastic properties, and mechanical properties. The general coating properties—including hardness, solvent resistance, impact resistance, and adhesion—were evaluated to demonstrate the practical application of the waterborne NIPU in coatings. The linseed oil-based waterborne NIPU coatings exhibited performance comparable to both a solvent-borne NIPU coating and a commercial waterborne isocyanate-based polyurethane coating.more » « less
-
Background Seed oils are widely used in the food, biofuel, and industrial feedstock industries, with their utility and value determined by total oil content and fatty acid composition. Current high throughput seed oil analysis methods either lack accuracy in total fatty acid profiling or require extensive labor for lipid extraction prior to derivatization to fatty acid methyl esters (FAME) and quantification by gas chromatography (GC). Alternatively, direct whole seed FAME production methods have been developed for the very small seeds in the model species Arabidopsis thaliana but these have generally not been adapted to larger seeds of most oilseed crops. Results High-throughput direct whole seed FAME production methods were optimized for seeds up to 5 mg each utilizing acid-catalyzed esterification. For the oilseed species Camelina sativa, Thlaspi avernse (pennycress), Cuphea viscosissima, and Brassica napus (var. Canola), the total seed fatty acid content and composition from direct seed esterification to FAME matched that of lipid extract derivatization demonstrating the accuracy of the methods. In combination with seed phenotyping using GridFree, this approach enabled the development of a rapid pipeline for simultaneous seed weight, count, size/shape phenotyping, and oil analysis. For the larger and tougher seeds produced by Limnanthes alba (Meadowfoam) and Cannabis sativa L. (hemp) the whole seed acid-based method proved insufficient, and prior laborious homogenization of seeds was required. Therefore, a rapid one-tube bead homogenization and base catalyzed-esterification method was developed. Base-derived fatty acid esterification cannot derivatize free fatty acids leading to slightly lower total seed fatty acid than acid-catalyzed methods, however the seed oil content and fatty acid composition that is valuable for screening large numbers of samples in research populations was accurately measured. Conclusions New rapid whole seed fatty acid esterification and phenotyping protocols were developed to accurately assess oilseed lipid content. These methods are particularly valuable in oilseed research, breeding, and engineering applications where efficient analysis of large numbers of samples and accurate oil fatty acid profiling is essential. While having been developed for current and emerging oilseed crops, these methods also provide a foundation from which protocols might be established for new and emerging crop species.more » « less
-
Presented is the synthesis of cyclic polyacetylenes from alkynes and a study probing the functional group tolerance of catalyst 1. The synthesized polymers were characterized by employing GPC, NMR, and IR spectroscopy. The cyclic polyacetylenes spontaneously degrade, leading to the formation of lower molecular weight linear analogues. The degradation rate varied significantly based on the monomer substituents. These discoveries collectively reveal the functional group limits of catalyst 1 and the subsequent stability of the synthesized polymers, thus opening new avenues for advanced polymer design and applications.more » « less
-
Degradable polymers are crucial in order to reduce plastic environmental pollution and waste accumulation. In this paper, a natural product, tannic acid was modified to be used as a polymer star core. The tannic acid was modified with atom transfer radical polymerization (ATRP) initiators and characterized by 1H NMR, FT-IR, and XPS. Twenty-five arm polymer stars were prepared by photoinduced ATRP of poly(methyl methacrylate) (PMMA) or poly(oligo(ethylene oxide) methacrylate) (molar mass Mw = 300 g/mol) (P(OEO300MA)). The polymer stars were degraded by cleaving the polymer star arms attached to the core by phenolic esters under mild basic conditions. The stars were analyzed before and after degradation by gel permeation chromatography (GPC). Cytotoxicity assays were performed on the P(OEO300MA) stars and corresponding degraded polymers, and were found to be nontoxic at the concentrations tested.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript
- Journal Article:
- https://doi.org/10.3390/polym15091993
