The positional distribution of the fatty acids on the triacylglycerol influences uptake of calcium, fat, and energy. The positional distribution of breast milk is similar, but not identical, to that of cow and goat milk, and is different to that of vegetable oil. Often, in infant formula a mixture of milk fat with certain vegetable oils is used, to mimic the positional distribution of breast milk. A method for the analysis of fatty acids at the sn-2 position in infant formula and adult/pediatric nutritionals by enzymatic transesterification is presented. The aim of this study is to demonstrate the suitability and applicability of the method to determine fatty acids at the sn-2 position of triacylglycerol molecules in infant formula and adult/pediatric nutritionals by enzymatic transesterification. The sample is extracted to isolate the fat, which is treated with a regiospecific enzyme to remove the sn-1(3) positions of the triacylglycerol, resulting in 2-monoacylglycerols. These are then separated using solid phase extraction, transesterified to fatty acid methyl esters, and analyzed using gas chromatography with flame ionization detection. The relative standard deviation repeatability (RSDr) and intermediate precision (RSDiR) were in the range of 1.2-5.2% (RSDr) and 2.0-13.3% (RSDiR). The accuracy was assessed by spiking experiments and model triglycerides, and recoveries were on average 95% (spiked addition) and 97% (model triglycerides). The limit of quantification (LOQ) was found at 0.003 g/100g on reconstituted product. The SLV demonstrates that it meets the criteria set in the Standard Method Performance Requirements (SMPRSM) 2022.004. A method to determine the content of fatty acids at the sn-2 position by use of an enzyme with good 1(3) regiospecificity was developed. The method complies to international and governmental regulations. The method was evaluated by the Expert Review Panel on Nutrient Methods, and granted first action status.

Fluorinated ionic liquids as gas chromatographic stationary phases for the separation of volatile per- and polyfluoroalkyl substances.

Fatty acid esters (FAE) can be found in textiles in many forms, both in manufacturing and as components of consumer products. Removal of FAEs and the resulting free fatty acids (FFA) poses a problem which can partially be solved by using enzymes. Lipases can potentially aid the removal of FAE-based spin-finishes and fatty stains from textile fibres. However, monitoring substrates and/or products of enzyme reactions is difficult, mainly because FAE and the resulting FFA are not sufficiently volatile for conventional analysis by gas chromatography (GC). Therefore, derivatisation is usually performed before analysis. Here, two methodologies for the analysis of FAE and FFA in textiles by GC (with mass spectrometer or flame ionisation detectors) were developed using methylation and silylation. While methylation allows for the analysis of total fatty acids (FAE + FFA), silylation allows the analysis of FFA/diacylglycerols/monoacylglycerols. Derivatisation of the sample by acid-catalysed methylation without prior extraction was found effective for total fatty acids analysis in both fat/oil soiled textiles and raw textiles containing spin-finishes. Silylation with N,O- bis(trimethylsilyl)trifluoroacetamide: trimethylchlorosilane allowed for the quantification of FFA in raw textiles, with a marked increase in concentration of FFA being observed after treatment with lipases. These derivatisation strategies allowed the evaluation of the performance of lipase-facilitated washing of textiles, by both (i) assessment of the efficiency of the overall washing process by the quantification of the FAE/FFA remaining on the textile, and (ii) determination of the activity of used lipases by quantification of the enzymatic hydrolysis products. • Development of a method for quantifying fatty acid (FA) esters and free FA by GC • The method was efficient using real matrices and substrates • Acid methylation without prior extraction allows for the quantification of total FA • Silylation determined the free FA produced by lipase hydrolysis of FA esters • Three lipases were active towards FA esters in textile stains and spin-finishes

Static headspace (SHS) sampling, prior to a gas chromatography (GC) separation, is an interesting approach in food analysis inasmuch that the isolated volatile fraction reflects the compounds that reach the human nose. Additionally, the fraction analyzed is free of less volatile compounds and, hence, contamination of the GC system is avoided. Further, such a sample preparation method is environmentally-friendly because organic solvents are not used. The main disadvantage of SHS sampling is a reduced analyte detectability, due to the lack of a pre-concentration step. The investigation is based on the use of SHS sampling prior to cryogenic modulation enantioselective comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (CM eGC×GC-ToFMS). The samples subjected to analyses were two Citrus essential oils, namely bergamot and sweet orange. A chiral-apolar combination of columns was used, enabling both general analyte profiling and the determination of enantiomer ratios. A direct comparison was made between SHS and the direct injection (DI) of sample solutions. The use of CM counterbalanced, to a certain extent, the SHS reduced analyte detectability. A total of 239 and 84 compounds were tentatively characterized in bergamot essential oil using DI and SHS, respectively, whereas 174 and 58 analytes were tentatively identified in sweet orange essential oil using the same techniques, respectively. The method was further used to investigate the enantiomeric ratios of several chiral components. Both sampling methodologies yielded comparable chiral profiles, although slight variations in enantiomeric distributions were observed. The use of SHS sampling combined with CM GC×GC has been rarely described. The results obtained through SHS eGC×GC-ToFMS appear to be of interest and, in principle, such an option can be applied to food analysis in general. The untargeted information can be used to confirm authenticity and define geographical origin, along with the determination of products of transformation.

Polycyclic aromatic hydrocarbons (PAHs) are organic pollutants widely abundant in multi-stressed coastal environments worldwide. Herein, seawater (dissolved phase/suspended particles) and sediment samples were collected during a survey on June 2024 across five stations, reflecting multiple anthropogenic stressors, at the heavily impacted Saronikos Gulf, Greece. In the collected samples, 47 PAH homologues were monitored by gas chromatography - mass spectrometry, resolved into source-related profiles by employing the EPA's Positive Matrix Factorization model and examined in relation to bacterial community composition inferred from eDNA metabarcoding sequencing. Our aim was to assess the potential links of PAH sources to microbial diversity and community structure, providing a targeted tool to support coastal monitoring of complex PAHs mixtures in multi-stressed environments. Total PAHs (TPAH₄₇) concentrations ranged between 127 and 462ngL-1 in the dissolved phase with alkylated 2- and 3-ring compounds dominating, 5.78-10.4ngL-1 in suspended particles and 860-5450ngg-1 in sediments, dominated by high-MW 4- to 7-ring compounds. Bacterial community composition based on 16S rRNA gene metabarcoding differed between seawater and sediments. In seawater, community co-varied with physicochemical gradients (temperature, salinity, dissolved oxygen, chlorophyll-a), while PAH source profiles showed weaker associations. In sediments, bacterial assemblages exhibited a stronger statistical association with source-resolved PAH profiles based on the constrained ordination framework. In the dissolved phase the taxa Flavobacterium, Sulfitobacter, and Labedella gwakjiensis, in the suspended particles the genus Algiphilus, and in sediments the species Parahaliea maris were identified as source-associated candidate indicator taxa, highlighting compartment-specific potential bioindicators that require functional validation with -omics tools.

Chlorpyrifos residue reduction in pistachios using a saponin-rich extract from Saponaria officinalis: An eco-friendly washing approach

Fabrication of a robust phenothiazine hyper-crosslinked polymer coated fiber for the determination of short-chain fatty acids in rat faeces by HS-SPME/GC-FID.

Electrocoagulation is used for wastewater (WW) management; however, the disposal of organic carbon- and metal ion-enriched electro-flocculated WW(EF) remains a significant challenge. We investigated the anaerobic digestion (AD) of raw sewage WW (RW) and EF for biohydrogen and biomethane production using a microbial consortia designed from complementary natural wastes selected for their distinct microbial complexity and buffering capacity. The consortia design included sequential mixing, heat-pretreatment, organic load shock, and anaerobic acclimatization for selective enrichment of fermentative, hydrogen-producing, and methanogenic communities. Three different heat-pretreatment consortia and their untreated counterparts were tested in two AD batch experiments (B1 and B3). Biogas production, gas compositions, and microbial dynamics were explored using gas chromatography and 16S rRNA gene sequencing. B3 reactors produced more biogas than B1 and controls, highlighting enhanced microbial activity after acclimatization. For RW, the heat-pretreated inoculum (R.C2Tx) yielded highest cumulative gas (81 mL) with 37% biomethane, attributed to enrichment of fermentative and hydrogenotrophic taxa. In contrast, the untreated consortia (E.C2UTx) performed better for EF (76.7 mL total biogas, 12.7% biomethane, and 5.8% biohydrogen), highlighting the enrichment of microbes with ability for degradation of Fe-rich, complex substrates. Enrichment of Proteobacteria, Pseudomonas, and Methanobacterium in most B3 samples correlated with higher gas yield.

The formation and stability of water-in-oil (W/O) emulsions in petroleum are strongly influenced by species that accumulate at the oil-water interface, collectively referred to as interfacial material (IM). Understanding the composition of IM is essential for clarifying the mechanisms responsible for emulsion stability and interfacial rigidity, although its high chemical complexity makes the identification of its major constituents challenging. In this study, IM fractions from four Brazilian crude oils were isolated using two methods, centrifugation followed by Dean-Stark distillation (IMR) and adsorption on wet silica (IMW), and then characterized by negative-ion electrospray Fourier-transform ion cyclotron resonance mass spectrometry (ESI(-) FT-ICR MS), gas chromatography with flame ionization detection (GC-FID), elemental analysis (CHNS-O), and mid-Fourier transform infrared spectroscopy (mid-FTIR). Their ability to stabilize emulsions was also evaluated. The results showed that both extraction methods enriched the IM fractions with highly polar oxygenated classes and reduced the relative contribution of pyrrolic species (N[H]) compared with the original crude oils. The wet silica method was more selective for highly polar compounds, particularly the O2[H] class, commonly associated with naphthenic acids and rigid interfacial films. In contrast, the centrifugation/Dean-Stark method recovered an interfacial fraction with broader compositional coverage, including lower-polarity classes such as NO2[H] and NO3[H], where GC-FID, elemental analysis, and FTIR analyses also confirmed a more aliphatic character for the IMR fractions obtained by centrifugation. Model emulsion tests further showed that the IM fractions obtained by centrifugation/Dean-Stark conferred greater stability to the W/O system than those isolated using wet silica, indicating that emulsion stabilization depends on the combined action of polar and nonpolar species.

Plant-derived extracellular vesicles (EVs) have attracted growing interest as scalable nanocarriers in medicine and biotechnology. Yet little is known about post-harvest processing particularly drying, affects their EV yield, size, morphology, and biochemical composition. In this study, microvesicles (MVs), a major class of EVs, were isolated via differential centrifugation and purified by size-exclusion chromatography. Then, MVs were characterized morphologically by transmission electron microscopy and assessed for hydrodynamic size and zeta potential using dynamic light scattering. Antioxidant activity was quantified through 2,2-diphenyl-1-picrylhydrazyl radical scavenging assays. Fatty acid profiles were determined by gas chromatography, while triterpenoids and polyphenols were quantified by high performance liquid chromatography. Spherical, cup-shaped vesicles were successfully isolated from both dried and fresh C. asiatica. Dried plant biomass yielded higher MV quantities, producing smaller vesicles comparable to fresh samples. Unique fatty acids-including trans-oleic, erucic, trans-linoleic acids- were detected exclusively in dried MVs, but not in fresh samples. Our findings demonstrated that dried medicinal herbs can serve as a practical and, in some respects, advantageous source of MVs compared to fresh material, providing higher yields while retaining key bioactive components. This supports potential future use of dried biomass for efficient and large-scale MV preparation, with application in biotechnology and possibly biomedicine.

Increasing detection sensitivity in gas chromatography by cooling a nano-gravimetric detector.

Stabilizing an scu-topology Zr-MOF via linker installation for enhanced gas chromatographic separation.

Periodontal disease (PD) is one of the most common infectious conditions in dogs, associated with plaque accumulation, gingival inflammation, halitosis, and tooth loss. Halitosis is primarily caused by volatile sulfur compounds (VSCs) generated by anaerobic bacteria, including Porphyromonas gulae (P. gulae), a pathogen closely linked to PD progression. This study examined the effects of oral interferon alpha (IFN-α) on halitosis and bacterial activity in dogs with PD. Thirty-two dogs with moderate-to-severe PD were enrolled and allocated to untreated controls (n = 10) or IFN-α treatment (n = 22). Dogs in the treatment group received 2.75 g of IFN-α formulation (InterBerryα®) applied to the gingival margin twice weekly for five weeks. Clinical outcomes included PD Severity Index, enzymatic activity to hydrolyze N-benzoyl-DL-arginine-naphthylamide (BANA), PCR detection of P. gulae, and halitosis evaluation by gas chromatography and pet owner assessment. IFN-α significantly reduced PD Severity Index, BANA activity, and VSC concentrations (hydrogen sulfide and methyl mercaptan) compared with baseline and controls. Additionally, 27% of treated dogs converted to P. gulae-negative status after therapy. Owners reported marked improvement in oral malodor. These findings suggest that oral IFN-α effectively alleviates halitosis and reduces periodontal pathogen activity, supporting its potential as a non-invasive treatment for canine PD.

Process evaluation of supercritical water liquefaction of mixed polyolefin wastes for integrated waste and energy systems

• PDMS demonstrated notable biodegradation under anaerobic sludge conditions through microbially mediated hydrolysis. • Structural analysis confirmed Si–O–Si bond cleavage and formation of silanol terminal groups during degradation. • Degradation led to a marked reduction in the thermal stability of PDMS. • Key degradation products identified were low-molecular-weight cyclic and linear siloxanes. • Degradation altered functional properties: dielectric constant decreased, viscosity dropped, and interfacial tension with water reduced. • Metagenomic analysis revealed an anaerobic consortium (e.g., Usitatibacter) enriched with genes for xenobiotics biodegradation. Polydimethylsiloxane (PDMS) is a widely used silicon-based polymer known for its excellent chemical and thermal stability, with broad applications in the power industry and consumer products. Due to its recalcitrance to degradation and persistence in the environment, PDMS has emerged as a potential organic pollutant. Therefore, developing effective environmental degradation methods is urgently needed, among which microbial degradation represents a promising solution. In this study, a laboratory-simulated anaerobic sludge environment was used to conduct an 18-day degradation experiment on PDMS. During this period, the PDMS samples exhibited a mass loss of approximately 28.50%. Structural changes during degradation were systematically analyzed using techniques such as gel permeation chromatography (GPC), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results indicated significant molecular chain scission of PDMS under anaerobic conditions. After 18 days of degradation, the molecular weight of the samples decreased by 24%. DSC and TGA showed a decline in the thermal properties of the degraded samples, with the initial decomposition temperature and glass transition temperature decreasing by 43.7°C and 3.1°C, respectively. Concurrently, the dielectric constant decreased across the measured frequency range, rheological properties decayed, and the interfacial tension between PDMS and water significantly dropped, indicating alterations in material polarity, flow behavior, and surface hydrophobicity. Additionally, nuclear magnetic resonance (NMR) spectroscopy, and Fourier-transform infrared (FTIR) spectroscopy revealed cleavage of Si–O–Si bonds, accompanied by enhanced –OH signals, indicating hydrolysis of the PDMS backbone and the formation of silanol terminals. Gas chromatography–mass spectrometry (GC–MS) analysis detected degradation products containing cyclic and linear low-molecular-weight siloxanes (D4, hydroxyl-terminated L4, etc.). Metagenomic analysis of the microbial community revealed an anaerobic consortium dominated by genera such as Usitatibacter, Aquihabitans , and Pseudomonas , whose functional gene profile demonstrated a strong potential for xenobiotics biodegradation and metabolism. Finally, from a microscopic perspective, this study elucidated the microbial-mediated hydrolysis mechanism of PDMS in anaerobic sludge, providing new insights for the development of biodegradation technologies for silicon-based polymers.

Characterization of the volatile fraction of used wind turbine blade pyrolysis oil by two-dimensional gas chromatography

Phthalates, parabens, benzophenone-3, bisphenols and triclosan are among the contaminants suspected of being involved in several hormone-related pathologies. In developing countries, weak regulations and lack of a precise monitoring plan lead to exposures that could be much worse than in developed countries. The objectives of this study were to evaluate the level of exposure of the adult population of Kinshasa in the Democratic Republic of the Congo to these compounds and to assess the health risk induced by these pollutants. Concentrations of four parabens, nine phthalate metabolites, two non-phthalate plasticizers, benzophenone-3, three bisphenols and triclosan were assessed in the urine of 145 volunteers recruited between November 2022 and January 2023 in Kinshasa. Measurements were performed using a liquid or a gas chromatography coupled to a mass spectrometer. Methylparaben (MeP: 62.6 μg/L), mono-n-butyl phthalate (MnBP: 78.1 μg/L) and bisphenol A (BPA: 1.54 μg/L) were detected in over 95% of urine samples, with exposure levels exceeding those observed in Western populations. For BPA and MnBP, 100% and 15% of the study samples, respectively, exceeded human biomonitoring guidance values (HBM-GV) proposed by the European Human Biomonitoring Initiative (HBM4EU) consortium, meaning that their exposure levels are associated with health concerns. The exposure of the population of Kinshasa to these pollutants merits consideration, as it constitutes a serious public health concern. To enhance protection, regulatory measures must be implemented and large-scale studies and awareness campaigns must be conducted.

Evaluation of measurement uncertainty for trace-level sulfur compounds analysis in fuel hydrogen using pre-concentration sulfur chemiluminescence detector gas chromatography

Comprehensive two-dimensional gas chromatography in environmental non-targeted analysis

Comparison of solid phase microextraction coatings for headspace extraction of volatile perfluoroalkyl substances using one-dimensional and comprehensive two-dimensional gas chromatography.