Real-time monitoring data regarding the emission behavior of medium chain fatty acid esters was still insufficient concerning their oxidative and low-temperature combustion characteristics. Herein, thermogravimetry-Fourier transform infrared spectroscopy-gas chromatography-mass spectrometry (TG-FTIR-GC-MS) was utilized to investigate the emission profile of coconut oil-derived methyl ester biodiesel (MECO) under air flow, with specific emphasis on medium chain fatty acid methyl ester’s oxidative degradation and simulated low-temperature combustion processes. To eliminate nitrogen interference, thermal decomposition behaviors of three high-boiling-point plant oil-based ethyl esters (PEEs), including ethyl ester of coconut oil (Cocos nucifera L., EECO), ethyl ester of palm oil (Elaeis guineensis, EEPO), and ethyl ester of cottonseed oil (Gossypium barbadense L., EECSO), were examined under nitrogen flow. The PEEs primarily release fatty acid ethyl esters, demonstrating that nitrogen is not involved in potential PEE pyrolysis. Under air flow, MECO undergoes ester bond cleavage, radical scission, and decarboxylation, yielding special short- to medium-chain alkanes. Reactive molecular dynamics simulations using methyl octanoate as the model compound further elucidated the potential degradation pathway under simulated air conditions. This work establishes a robust framework for understanding potential thermal oxidative degradation of medium chain fatty acid esters, shedding some light on optimizing fuel formulations.

Furan fatty acids (FuFAs) are special minor dietary lipids characterized by a furan ring structure, widely present in food sources, such as fish and plant oils. They exhibit potent antioxidant and anti-inflammatory activities, along with potential benefits for cardiovascular and metabolic health, with evidence suggesting that their physiological significance may surpass that of omega-3 fatty acids. However, the development of reliable methods for screening and structural elucidation of FuFAs in complex matrices has been hindered by the limited availability of chemical standards and their inherent photosensitivity. Herein, we propose a nontargeted liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS)-based method for the detection of free FuFAs using a trifluoromethyl-substituted phenyl bromoacetamide derivatization strategy. This labeling approach induces specific fragmentation during MS/MS analysis, generating diagnostic fragment ions derived from the furan moiety. Through comprehensive evaluation of various carboxylic acid derivatization reagents, including comparing retention behavior, isotopic patterns, fragmentation profiles, analytical performance in real samples, and theoretical calculations, the proposed method based on specific MS/MS fragmentation patterns was demonstrated to enable direct determination of FuFAs in complex lipid matrices, such as fish and plant oils. Furthermore, it facilitates the preliminary identification of key structural features of FuFAs, including the number of double bonds and substituent positions, and allows for structural assignment with minimal reliance on reference standards. This approach provides a straightforward, efficient, and data-simplified strategy for the structural identification of FuFAs in complex matrices.

Furan fatty acid (FuFA) exhibits antioxidant and anti-inflammatory properties, thereby reducing cardiovascular risks in humans. However, the availability of chemical standards for free FuFAs are limited. Some of them show poor tolerance toward acidic environments, elevated temperatures, and light exposure. Few accurate and efficient structural elucidation method has been developed for their non-targeted screening in complex matrices. This pilot study describes a novel approach that combines orthogonal functional group tagging with computational retention time (RT) prediction to identify potential free FuFA across different plant oil samples. The tagging of the furan ring skeleton and carboxylic group was achieved by direct condensation using two derivatization reagents, 1-cyclohexyl-3-(2-morpholinoethyl)carbodiimide (CMCT) and 4-phenyl-3H-1,2,4-triazole-3,5(4H)-dione (PTAD), respectively. The liquid chromatography-mass spectrometry (LC-MS) analysis of CMCT and PTAD derivatives of furan ring-containing carboxylic acids reveals that the RTs for CMCT derivative exceeded those of PTAD derivatives; CMCT derivatives generated [M-101.0841]+ and [M-125.0841]+ product ions, while PTAD derivatives produced [PTAD]- and [M-43.9898]- product ions. In the presence of straight-chain saturated fatty acids (C8:0-C20:0) within plant oil, computational RTs of putative 151 FuFAs located among C8:0-C20:0, facilitating the establishment of a predicted RT region mapping. It further identified the potential FuFA features picked out through the screening method to minimize false positive results. Although we ultimately not find any free FuFAs from the investigated samples, the results demonstrated that the procedure of FuFA screening dramatically mitigates false positive results during structural elucidation in the case of lack of chemical standards for comparison.

Furan fatty acids (FuFAs) demonstrate superior antioxidant properties compared to singlet oxygen and free radical scavengers. Identifying FuFAs in potential raw materials for biodiesel production and converting them to corresponding methyl esters can enhance the auto-antioxidant properties, thereby improving biodiesel's oxidative stability. However, current methods for identifying FuFAs are constrained by their instability and the lack of chemical standards. In this study, we present a density functional theory (DFT) assisted 1H nuclear magnetic resonance (NMR) spectroscopy method to identify and quantify potential FuFAs during the oxidation process of plant oil samples, including coconut oil (Cocos nucifera L.), cotton seed oil (Gossypium barbadense L.), and palm oil (Elaeis guineensis). The characteristic hydrogen chemical shift (delta H) at 2.47-2.66 ppm and 6.02-6.23 ppm for FuFA discovering were obtained from 18 putative FuFAs with varying chain lengths and methyl substituents. These predicted chemical shifts were utilized to detect FuFAs in plant oil samples and straight-chain long-chain fatty acids following a ten-day oxidation process. The results showed that no FuFAs were detected using our predicted 1H NMR method. Additionally, the differences in oxidation patterns among the three plant oil samples were examined to underscore the impact of distinct fatty acid compositions on FuFA formation and other oxidation products. Our methodology circumvents the limitations of complex pretreatment and the scarcity of chemical standards for FuFAs detection, making it applicable to other real samples.

This paper introduces a transformative hydrodeoxygenation process for the simultaneous recovery of oil and iron from hazardous rolling oil sludge (ROS). Leveraging the inherent catalytic capabilities of iron/iron oxide nanoparticles in the sludge, our process enables the conversion of fatty acids and esters into hydrocarbons under conditions of 4.5 MPa, 330 °C, and 500 rpm. This reaction triggers nanoparticle aggregation and subsequent separation from the oil phase, allowing for effective resource recovery. In contrast to conventional techniques, this method achieves a high recovery rate of 98.3% while dramatically reducing chemical reagent consumption. The reclaimed petroleum and iron—ready for high-value applications—are worth 3910 RMB/ton. Moreover, the process facilitates the retrieval of nanoscale magnetic Fe and Fe0 particles, and the oil, with an impressive hydrocarbon content of 87.8%, can be further refined. This energy-efficient approach offers a greener, more sustainable pathway for ROS valorization.

The toxicity and environmental persistence of perfluorooctanoic acid (PFOA), and perfluorooctane sulfonate (PFOS) are of great concern for food intake in humans. However, PFASs conversion or conjugation to other substances in rice grown on PFASs polluted soil has not been explored clearly. These unknown transformed or conjugated products of PFOA and PFOS could be harmful to human health. The restriction factor in evaluating the possible transformation of PFOA and PFOS is mainly attributed to the lack of an efficient method for screening PFOA and PFOS and their related metabolites. To circumvent this challenge, we established a non-targeted screening method by combining a fluoro-cotton fiber-based solid phase extraction (FC-SPE) and liquid chromatography-high resolution mass spectrometry (LC-HRMS) to monitor the formation of possible organic fluorine compounds from rice (Oryza sativa L.) grown on PFASs. We synthesized fluoro-cotton fibers to serve as the FC-SPE packing material and characterized by field-emission scanning electron-microscope, Fourier transform infrared, and X-ray photoelectron spectroscopy measurements. The optimal extraction conditions for the prepared FC-SPE were investigated. The performance of FC-SPE in LC-MS analysis was validated by linearity, precision, recovery, and matrix effect. Then the FC-SPE combined with LC-HRMS was used to specifically capture organic fluorine compounds from complex matrices via F-F interaction, including rice seedlings grown in PFOA and PFOS polluted soil and soil samples. By the established FC-SPE LC-HRMS method, in total 429 features were found as the possible organic fluorine compounds from rice seedlings grown in PFOA polluted soil among the 1781 features from the rice seedlings. Finally, we employed a13C metabolic tracing analysis of organic fluorine compounds in combination with the FC-SPE LC-HRMS method to further identify the features that detected from rice seedlings grown in PFOA polluted soil. The final result indicated that there were not any new organic fluorine metabolites screened out from rice grown in PFOA or PFOS polluted soil.

In this study, a novel modified metal organic framework (MOF) was prepared and used as adsorbent of miniaturized solid-phase extraction (M-D-mu SPE) for analyzing 8-2 FTOH and its metabolites in edible tissues by LC-MS/MS. This synthesized adsorbent, named as Fe3O4@Fe-MIL 101-NH2 (magnetic Fe-MOF), was characterized. Moreover, the effects factors on the adsorption behavior of the adsorbents for the analytes were investigated and optimized in detail, such as solution pH, adsorbent amount, extraction time, desorption condition. The adsorbtion mechanism of magnetic Fe-MOF might be electrostatic interaction, CF-pi hydrophobic and Lewis acid base. Compared with conventional adsorbents (such as PSA, C18), magnetic Fe-MOF reduced matrix effect. The limits of quantification ranged 0.10-1.5 mu g/kg. The recoveries of analytes ranged 78.0% - 90.3% in spiked samples, with relative standard deviations less than 12.0%. The developed method was successfully utilized to analyze incurred samples, which proves that it is a rapid, efficient, and sensitive method.

Sensing detection of Hg2+ and Cu2+ with use of a single organic probe is of practical importance, but there still remains a great challenge to implement the detection in pure aqueous media while avoiding mutual interference. Herein, a novel polymer chemosensor, P(META-co-RhBH–HB–Ac), was fabricated by incorporating rhodamine hydrazone moieties into a quaternary ammonium-type poly(ionic liquid). With the positively charged character of polymeric backbone, the P(META-co-RhBH–HB–Ac) exhibited a high solubility in water, and possessed a potential advantage in minimizing nonspecific binding. More importantly, the P(META-co-RhBH–HB–Ac) could serve as a dual-analyte chemosensor for differential recognition of Hg2+ and Cu2+ in pure aqueous media based on unique UV irradiation-dependent response behaviors. Specifically, Hg2+ was exclusively sensed through fluorescence enhancement in the absence of UV irradiation, while selective colorimetric response to Cu2+ was achieved under UV irradiation. Particularly, benefitting from the electrostatic effect of META units on RhBH–HB–Ac receptors, the P(META-co-RhBH–HB–Ac) could discriminate Hg2+ and Cu2+ under their coexistence without occurrence of mutual interference. Consequently, selective and differential determination of Hg2+ and Cu2+ under pure aqueous conditions was achieved, which proved to be applicable for quantitative analysis of real water samples.

Expanding the availability of hydrophobic small-molecule probes in pure aqueous environments is an important issue likely to significantly impact their application prospects in sensing detections. The present work demonstrates for the first time that poly(ionic liquid) (PIL) can serve as a superior carrier, which not only enables hydrophobic small-molecule probes to readily disperse in pure water and but helps maximize their sensing performances. As a proof-of-concept, a hydrophobic rhodamine derivative carried by PIL, P(RhBHSA-co-META), was designed and applied for the colorimetric determination of Cu2+ and further for CN- in fully aqueous solutions. Due to the positively charged nature of polymeric backbone, the P(RhBHSA-co-META) was highly water-soluble and could avoid non-specific bonding. Moreover, the strong inter- and intra-chain electrostatic repulsions made the P(RhBHSA-co-META) possible to be fully free and highly stretched in water, facilitating the accessibility of receptor binding sites. Excellent sensing performance of P(RhBHSA-co-META) toward Cu2+ was achieved in terms of high sensitivity, ultrafast color/absorption response, and excellent anti-disturbance ability. Furthermore, the pre-formed P(RhBHSA-co-META)-Cu2+ complex was also verified to be highly efficient for colorimetric determination of CN-, exhibiting high sensitivity and selectivity. This study provides a simple, effective, and extendable approach for designing water-soluble chemosensors for ion detections and other sensing applications. (C) 2017 Elsevier B.V. All rights reserved.