High-resolution Gas Chromatography Research Articles

High-resolution subtyping of fibroblasts in gastric cancer reveals diversity among fibroblast subsets and an association between the MFAP5-fibroblast subset and immunotherapy

BackgroundsGastric cancer (GC) remains a global health threat due to frequent treatment failures caused by primary or acquired resistance. Although cancer-associated fibroblasts (CAFs) have been implicated in this process, it is still unclear which specific subtype(s) of CAFs hinder T-cell infiltration and promote resistance to immunotherapy.MethodsWe analyzed the GC fibroblast atlas in detail by combining 63,955 single cells from 14 scRNA-seq datasets. We also performed RNA-seq data in a local GC cohort and examined 13 bulk RNA-seq datasets to understand the biological and clinical roles of different CAF subsets. Additionally, we conducted in vitro experiments to study the role of specific proteins in GC development.ResultsWe identified a total of 17 fibroblast subsets in gastric cancer, nine of which did not fit into the existing CAFs classification. These subsets exhibited significant heterogeneity in distribution and biological characteristics (metabolism, cell-cell interactions, differentiation state), as well as clinical functions such as prognosis and response to immunotherapy. In particular, cluster 6 stood out for its high expression of MFAP5, CFD, and PI16; it was found to be negatively associated with both overall survival and response to immunotherapy in GC. This association was linked to an immunosuppressive microenvironment characterized by an increase in M2 macrophages but higher levels of T cell dysfunction and exclusion—a feature shared by tumors expressing MFAP5. Furthermore, the addition of human recombinant MFAP5 promoted proliferation and migration of HGC-27 cells by inducing the MFAP5/NOTCH1/HEY1 signaling pathway.ConclusionWe introduce a high-resolution GC fibroblast atlas. The 17 identified fibroblast clusters provide valuable opportunities for gaining deeper biological insights into the relationship between fibroblasts and GC development. Particularly, cluster 6 and its specific marker MFAP5 could serve as prognostic factors in GC and form a foundation for personalized therapeutic combinations to address primary resistance to ICIs.

Liquid crystal monomers in human, dog and cat feces from the United States

Little is known about exposure of humans and companion animals to liquid crystal monomers (LCMs), which are extensively used in digital displays. We determined the concentrations of 52 LCMs in feces of humans, pet dogs and cats from New York State, USA, using gas chromatography-high resolution mass spectrometry (GC-HRMS). Twenty-four, eight, and six LCMs, that were mainly fluorinated, were detected in human, dog, and cat feces, respectively. ∑LCMs concentrations in the feces of humans (mean: 8.01 ng/g dry weight [dw]) were significantly higher (p < 0.05) than those of dogs (mean: 1.82 ng/g dw) and cats (mean: 1.24 ng/g dw) and with concentrations measured as high as 39.8 ng/g dw. Rel-4′-((1r,1′r,4 R,4′R)−4′-ethyl-[1,1′-bi(cyclohexan)]−4-yl)−3,4-difluoro-1,1′-biphenyl (RELEEBCH or 2bcHdFB) was found at the highest detection frequency (DF) among LCMs analyzed in human (DF: 89 %), dog (DF: 28 %), and cat (DF: 50 %) feces, although this compound accounted only < 4 % of ∑LCM concentrations. The mean cumulative daily intakes of ∑LCMs, calculated through a reverse dosimetry approach, were 71.7, 87.5, and 10.7 ng/kg body weight (bw)/day for humans, dogs, and cats, respectively. This study provides evidence of exposure of both humans and pets to LCMs, highlighting the importance of assessing sources of exposure and associated health risks.

SPME arrow-based extraction for enhanced targeted and untargeted urinary volatilomics

BackgroundVolatile organic compounds (VOCs) present in human urine are promising biomarkers for various health conditions and environmental exposures. However, their reliable detection is challenging due to the complexity of urinary matrices and the low concentrations of VOCs. Moreover, untargeted approaches present considerable challenges in terms of data interpretation, increasing the complexity of method development. Here we address these challenges by developing a new method that combines solid-phase microextraction (SPME) Arrow with gas chromatography-high resolution mass spectrometry (GC-HRMS), using a design of experiments (DOE) approach for targeted and untargeted compounds. This methodology, specifically tailored for SPME Arrow, represents a significant advancement in untargeted urinary analysis. ResultsThe method was developed based on targeted and untargeted outcomes, were ranking results focus on the highest response area of 11 spiked target VOCs representative of urinary volatilomics, and on identifying the maximum untargeted number of VOCs. The method was developed focusing on the highest response area of 11 spiked target VOCs representative of urinary volatilomics and identifying the maximum number of VOCs. A univariate method determined the optimal coating type, urine volume, and salt addition. Subsequently, a central composite design (CCD) DOE was used to determine ideal temperature, extraction, and incubation times. The best method obtained has an extraction time of 60 min at a temperature of 53 °C, with an SPME Arrow CAR/PDMS using 2 mL of urine, with 0.25 % w/v of NaCl and a pH of 2. Compared to conventional SPME fibers, the SPME Arrow showed improved extraction efficiency, detecting more VOCs. Finally, the enhanced method was successfully applied to urine samples from children exposed and non-exposed to tobacco smoke, identifying specific VOCs, like p-cymene and p-isopropenyl toluene related to tobacco exposure. SignificanceBy integrating both targeted and untargeted approaches, the developed method comprehensively captures the complexity of urinary metabolomics. This dual strategy ensures the precise identification of known compounds and the discovery of novel biomarkers, thereby providing a more complete metabolic profile. Such an approach is crucial for advancing in non-invasive diagnostics and environmental health studies, as it offers deeper insights into the intricate relationships between metabolic processes and various health conditions.

Nylon 6 film coated with poly-tetrahydrofuran sol–gel solution in face mask as a non-invasive in vivo sampling device for caffeine in human exhaled breath aerosol

Caffeine is an alkaloid compound that can excite the central nervous system and effectively relieve fatigue in moderation. However, excessive caffeine consumption can block blood vessels, raising blood pressure and increasing the risk of atherosclerosis. The International Agency for Research on Cancer of the World Health Organization has listed caffeine in category 3 carcinogens, so it is crucial that caffeine be detected easily and accurately. Exhaled breath aerosol (EBA), which consists of a large number of volatile substances and complex biological matrices, can not only reflect the physiological state of the human body, ingested substances, and environmental exposures; on the other hand, the characteristics of non-invasive sampling also make EBA analysis has a broad application prospect in the field of human health monitoring and disease diagnosis. This paper used a combination of nylon 6 film coated with poly-tetrahydrofuran (PTHF) and a medical N95 mask to construct a convenient and direct sampling device, which can be used to collect caffeine ingested by humans non-invasively from EBA. Volunteers wore a mask for a defined period of time after consuming a certain amount of caffeine. The samples were next back-extracted with methanol and detected and analyzed using gas chromatography-high resolution mass spectrometry (GC-HRMS). The results showed that under the optimized analytical conditions, the PTHF-coated nylon 6 film was effective in collecting caffeine from human EBA, and the peak time of caffeine was 23.44 min. The mask-loaded coated device in this study has the advantages of being comfortable and efficient, safe and non-invasive as well as easy to operate, and by combining with mass spectrometry molecular techniques it can achieve high sensitivity and specificity analysis of trace components, which is expected to be used for the early diagnosis of respiratory diseases in clinical analysis.

Cadmium-Induced Changes in the Accumulation of Sugars and the PsGolS Transcript in Pisum sativum L.

Cadmium (Cd) is a key stress factor that affects plant development. To examine the influence of Cd stress, we analysed the tissue localisation of polysaccharides (Periodic Acid Schiff reaction), qualitative and quantitative changes in soluble carbohydrates (High-Resolution Gas Chromatography), and the expression of the galactinol synthase (PsGolS) and raffinose synthase (PsRS) genes in 4-week-old Pisum sativum L. ‘Pegaz’. The plants were treated with 10, 50, 100, and 200 µM CdSO4 for one week and analysed on the 1st, 7th, and 28th days after Cd application. Pea as an excluder plant accumulated Cd mainly in the roots. Cd induced starch grain storage in the stems and the accumulation of soluble carbohydrates in roots and shoots after 28 days of Cd treatment. In controls, soluble carbohydrate levels decreased during the plant growth. In addition, Cd increased galactinol and raffinose levels, indicating their important role in response to Cd stress in peas. Moreover, the analysis confirmed that the expression of PsGolS was induced by Cd. Overall, the results of the distribution of carbohydrates in pea plants, together with the inhibition of seed production by Cd, indicate that plants tend to allocate energy to stress response mechanisms rather than to reproductive processes.

Optimizing COF crystallinity for high-resolution GC separation

This research explores the influence of crystallinity on gas chromatographic (GC) separation using covalent organic frameworks (COFs) as stationary phases. Three COF materials (CTF-DCBs) with varying crystallinity were synthesized and characterized. CTF-DCB-1, with superior crystallinity, demonstrated high-selectivity GC separation of benzene isomers as well as styrene/phenylacetylene mixtures, while CTF-DCB-2 and CTF-DCB-3 exhibited lower crystallinity and worse separation performance. Thermodynamic and kinetic tests showed that CTF-DCB-1 had the worst thermodynamic adsorption but low diffusion mass transfer resistance, which resulted in the best separation. Therefore, optimizing the crystallinity of COFs is necessary for balancing the kinetic diffusion and thermodynamic interactions towards the analytes, achieving high-performance GC stationary phases.

Identifying potential breath biomarkers for early diagnosis of papillary thyroid cancer based on solid-phase microextraction gas chromatography-high resolution mass spectrometry with metabolomics.

Thyroid cancer incidence rate has increased substantially worldwide in recent years. Fine needle aspiration biopsy (FNAB) is currently the golden standard of thyroid cancer diagnosis, which however, is invasive and costly. In contrast, breath analysis is a non-invasive, safe and simple sampling method combined with a promising metabolomics approach, which is suitable for early cancer diagnosis in high volume population. This study aims to achieve a more comprehensive and definitive exhaled breath metabolism profile in papillary thyroid cancer patients (PTCs). We studied both end-tidal and mixed expiratory breath, solid-phase microextraction gas chromatography coupled with high resolution mass spectrometry (SPME-GC-HRMS) was used to analyze the breath samples. Multivariate combined univariate analysis was applied to identify potential breath biomarkers. The biomarkers identified in end-tidal and mixed expiratory breath mainly included alkanes, olefins, enols, enones, esters, aromatic compounds, and fluorine and chlorine containing organic compounds. The area under the curve (AUC) values of combined biomarkers were 0.974 (sensitivity: 96.1%, specificity: 90.2%) and 0.909 (sensitivity: 98.0%, specificity: 74.5%), respectively, for the end-tidal and mixed expiratory breath, indicating of reliability of the sampling and analysis method CONCLUSION: This work not only successfully established a standard metabolomic approach for early diagnosis of PTC, but also revealed the necessity of using both the two breath types for comprehensive analysis of the biomarkers.

Prevalence of Psychoactive Substance Use During Pregnancy in Argentine Women: A Pilot Study Testing Maternal Hair.

The use of psychoactive substances (PSs) during pregnancy is a major public health concern because of their increasing prevalence worldwide. This study examined the understudied issue of gestational PS consumption in a cohort of Argentine delivering mothers. A cross-sectional pilot study involving 51 women receiving delivery care was conducted at the Santa Rosa Hospital in La Pampa, Argentina. Information on maternal sociodemographic characteristics, pregnancy history, and drug use was obtained through standardized interviews. Maternal hair samples were analyzed for alcohol, tobacco, licit, illicit, and prescription substance biomarkers using ultra-high-performance liquid chromatography high-resolution mass spectrometry and gas chromatography mass spectrometry. During pregnancy, 49.0% of participants reported alcohol consumption, 25.5% reported tobacco use, and 23.5% reported cannabis use. Hair samples from 56.9% of the women were positive for illicit PSs, with the most frequent being cocaine (41.2%) and cannabis (15.7%). Among the women, 47.1% consumed alcohol during pregnancy. Of the 24 women with hair ethyl glucuronide ≥5 pg/mg, 33.3% drank until the end of gestation and 58.3% started a social drinking habit in the second half. The analysis also detected prescription substances (anticonvulsants, antidepressants, methadone, opioids, antihistamines, antiemetics, and analgesics), caffeine (70.6%), lidocaine, and levamisole, some of which were cocaine or opioid adulterants. This is the first study to objectively assess the consumption of licit and illicit PSs during pregnancy in Argentina. In contrast to most nearby countries, cocaine was the most detected illicit PS in this cohort of Argentine delivering women. This finding highlights the importance of regular monitoring of local trends in PS use during pregnancy.

Chemical impurity profiling: Linkage of starting materials and an intermediate synthesis product of a carbamate chemical warfare agent

Establishing links between starting materials and products is highly valuable in the investigation of the use of toxic chemicals for illicit purposes. In this study, impurity profiling was performed on starting materials and their synthesis product, 2-([dimethylamino]methyl)pyridin-3-yl dimethylcarbamate, an intermediate compound in the production route for the carbamate class of Chemical Warfare Agents. The aim was to link the five commercial starting materials to the correct synthesis products. Initially, the intermediate compound was synthesized using different batches of the two starting materials (2 plus 3 batches), producing six unique combinations. All synthesis batches and the different starting materials were analysed by gas chromatography-high resolution mass spectrometry (GC-HRMS). Chemometrics analyses were conducted with principal component analysis and orthogonal projections to latent structures discriminant analysis to extract chemical impurity profiles and to build supervised classification models.Additionally, 12 test set samples, produced using the same starting materials by two different chemists in another laboratory, were analysed by GC-HRMS. A classification model able to distinguish all supplier combinations was successfully created and used to link the test set samples to their corresponding starting material.Furthermore, a new set of synthesis samples was extracted with a work-up procedure before analysis to investigate the effect of higher sample purity on the classification model. The results show that linking the synthesis products to their starting materials was successful for one of the starting materials, despite the purification procedure.

The Indiscriminate Chemical Makeup of Secondary Metabolites Derived from Endophytes Harvested from Aloe barbadensis Miller in South Africa's Limpopo Region.

The efficacy of 23 bacterial isolates obtained from surface-sterilized stems and leaves of three medicinal plants (Aloe barbadensis Miller, Artemisia afra, and Moringa oleifera) was investigated in an endeavour to prevent the growth of Mycobacterium bovis using the cross-streak method. Endophytes were isolated by incubating sterile plant materials on nutrient agar at 30 °C for 5 days. Two isolates showing activity were subsequently utilized to produce the extracts. Whole-genome sequencing (WGC) was used to identify the isolates. Secondary metabolites produced after 7 days of growth in nutrient broth were harvested through extraction with ethyl acetate. The extracts were chemically profiled using gas chromatography-high resolution time-of-flight mass spectrometry (GC-HRTOF-MS). NCBI BLAST search results revealed that the isolated endophytes belonged to the Pseudomonas and Enterobacter genera, based on WGC. Two endophytes, Aloe I4 and Aloe I3-I5 from Aloe barbadensis, exhibited potency based on the cross-streak method. The metabolite profiling of the selected endophytes identified 34 metabolites from Aloe I4, including ergotamine, octadecane, L-proline and 143 other metabolites including quinoline and valeramide, which inhibit microbial quorum sensing. These findings suggest that bacterial endophytes from medicinal plants, particularly Aloe barbadensis, hold promise as sources of antimycobacterial agents for human health applications.

Structural elucidation of derivatives of polyfunctional metabolites after methyl chloroformate derivatization by high-resolution mass spectrometry gas chromatography. Application to microbiota metabolites

Metabolomics has become an essential discipline in the study of microbiome, emerging gas chromatography coupled to mass spectrometry as the most mature, robust, and reproducible analytical technique. Silylation is the most widely used chemical derivatization strategy, although it has some limitations. In this regard, alkylation by alkyl chloroformate offers some advantages, such as a rapid reaction, milder conditions, better reproducibility, and the generation of more stable derivatives. However, commercial spectral libraries do not include many of the alkyl derivatives, mainly for polyfunctional metabolites, which can form multiple derivatives. That introduces a huge bias in untargeted metabolomics leading to common errors such as duplicates, unknowns, misidentifications, wrong assignations, and incomplete results from which non-reliable findings and conclusions will be retrieved. For this reason, the purpose of this study is to overcome these shortcomings and to expand the knowledge of metabolites in general and especially those closely related to the gut microbiota through the thorough study of the reactivity of the different functional groups in real matrix derivatized by methyl chloroformate, a common representative alkylation reagent. To this end, a systematic workflow has been developed based on exhaustive structural elucidation, along with computational simulation, and taking advantage of the high sensitivity and high-resolution gas chromatography-mass spectrometry. Several empirical rules have been established according to chemically different entities (free fatty acids, amino acids, polyols, sugars, amines, and polyfunctional groups, etc.) to predict the number of derivatives formed from a single metabolite, as well as their elution order and structure. In this work, some methyl chloroformate derivatives not previously reported as well as the mechanisms to explain them are given. Extremely important is the interconversion of E- and Z- geometric isomers of unsaturated dicarboxylic acids (case of fumaric-maleic and case of citraconic-mesaconic acids), or the formation of cycled derivatives for amino acids, as well as common metabolites, as in the case of serine and cysteine, and many others.

Comprehensive two-dimensional gas chromatography-high resolution mass spectrometry for the detailed qualitative analysis of old vine Chenin blanc wine volatiles and comparison with young vine Chenin blanc wines

Old vine Chenin blanc (OVC) wines are produced from grapes harvested from vines older than 35 years, verified as Certified Heritage Vineyards in South Africa. This emerging premium wine style is of interest due to the purported unique sensory properties of these wines, including their complex aroma. There is however limited information available on the volatile constituents of these wines, which are primarily responsible for perceived aroma. The wine volatilome is exceedingly complex, and requires advanced analytical approaches to investigate. The present contribution reports the evaluation of comprehensive two-dimensional gas chromatography (GC × GC) as a powerful separation technique to gain qualitative insight into the volatile composition of OVC wines. Extraction of volatile compounds was performed using headspace solid-phase microextraction (HS-SPME), while the GC × GC separation was hyphenated to high speed high resolution time-of-flight MS (HR-TOF-MS) for compound identification. A representative set of eight Chenin blanc wines produced from young vines (YVC) was also analysed to investigate the potential use of GC × GCHR-MS data to differentiate these two wine styles based on differences in their volatile composition. The results confirm the utility of GC × GCHR-MS for the detailed qualitative analysis of wine volatiles, with a total of 277 compounds identified in the studied wines. 53 compounds were uniquely identified in the OVC samples, and 52 in YVC wines. Successful differentiation of the young- and old-vine wines was achieved based on tile-based Fisher (F) ratios and principal component analysis (PCA), although this differentiation could not be clearly linked to winemaking practices (wood maturation) or viticultural origin.

Nutritional quality of selected commercially available seed oils and effect of storage conditions on their oxidative stability.

The primary objective of this research was to investigate nutritional composition of soybean, canola, cottonseed, palm and rapeseed oils under and the effect of storage conditions on their oxidative stability. Nutritional quality of selected seed oils was determined in term of fatty acids, tocopherols and tocotrienols compositions, total phenolic, total flavonoids and mineral contents. High resolution gas chromatography (HR-GC) analysis showed the presence of saturated, monounsaturated and polyunsaturated fatty acids having range from 9.21-43.25, 27.01-58.87 and 29.23-57.75 g/100g, respectively in all the oils. High performance liquid chromatography (HPLC) analysis revealed that γ-tocopherol was the major tocopherol followed by α-tocopherol in most of the oils. Spectrophotometric analysis showed that the total phenolic contents were 2.84-14.44 mg/g of oil, measured as gallic acid equivalent and total flavonoid contents were 0.44-1.56 mg/g of oil, measure as quercetin equivalent. Inductively coupled plasma-optical emission spectrophotometer analysis revealed that Mg, Fe and Mn were present in higher concentration ranging from 57.14-114.85, 126.87-460.06 and 106.85-538.39 μg/ml respectively. For study the effect of various storage conditions on the oxidation parameters, free fatty acid, peroxide value, para-anisidine value, conjugated dienes and trienes values were determined and ranging from 0.48-1.65, 10.65-40.15 meq/kg, 9.98-33.30, 8.74-28.41 and 3.86-15.02, respectively after 90 days storage. Statistical analysis revealed that various storage conditions exerted significant (p ≤ 0.05) effect on the oxidative stability of selected oils to different extent.

A chiral emissive porous organic cage used for high-resolution gas chromatography separations

The illustration of a chiral and porous tubular organic molecular cage (3P-1) was obtained through a [3+6] imine condensation reaction that used as the chiral stationary phase for preparing a 3P-1-coated capillary column by the static coating method.

An Integrated Workflow Assisted by In Silico Predictions To Expand the List of Priority Polycyclic Aromatic Compounds.

The limited information in existing mass spectral libraries hinders an accurate understanding of the composition, behavior, and toxicity of organic pollutants. In this study, a total of 350 polycyclic aromatic compounds (PACs) in 9 categories were successfully identified in fine particulate matter by gas chromatography high resolution mass spectrometry. Using mass spectra and retention indexes predicted by in silico tools as complementary information, the scope of chemical identification was efficiently expanded by 27%. In addition, quantitative structure-activity relationship models provided toxicity data for over 70% of PACs, facilitating a comprehensive health risk assessment. On the basis of extensive identification, the cumulative noncarcinogenic risk of PACs warranted attention. Meanwhile, the carcinogenic risk of 53 individual analogues was noteworthy. These findings suggest that there is a pressing need for an updated list of priority PACs for routine monitoring and toxicological research since legacy polycyclic aromatic hydrocarbons (PAHs) contributed modestly to the overall abundance (18%) and carcinogenic risk (8%). A toxicological priority index approach was applied for relative chemical ranking considering the environmental occurrence, fate, toxicity, and analytical availability. A list of 39 priority analogues was compiled, which predominantly consisted of high-molecular-weight PAHs and alkyl derivatives. These priority PACs further enhanced source interpretation, and the highest carcinogenic risk was attributed to coal combustion.

Chemical characteristics and biological activity screening of Pistacia lentiscus mastic gum and leaves from Türkiye.

Mastic gum is a resin that is produced by Pistacia lentiscus. It has many traditional uses, dating from ancient times, such as the treatment of gastrointestinal disorders and as a food additive. In this study, the leaves and mastic gum of trees of different ages from Karaburun and the Cesme peninsula in Türkiye were examined chemically and biologically. Flavonoids, and phenolic and fatty acid components were evaluated by a liquid chromatography system coupled with high resolution mass spectrometry (LC-HRMS) and gas chromatography with flame ionization detection (GC-FID). Cytotoxicity was screened against several cancer and healthy cell lines using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. Inducible nitric oxide synthase (iNOS) inhibition was determined on lipopolysaccharide (LPS)-induced murine macrophage cell line(RAW264.7) cells. Antiviral activity was measured against avian coronavirus using an in ovo virucidal antiviral activity assay. The main phenolic constituents of the gum were found to be salicylic, rosmarinic, and caffeic acids whereas the most abundant compounds detected were flavonoids in the leaf extracts. The most abundant fatty acids in hexane extracts were palmitic and oleic acids. All gum extracts except 3-year-old gum had significant cytotoxic activity on HeLa (IC50 1.74 ± 0.03-4.76 ± 0.95) and PC-3 (0.64 ± 0.25-6.22 ± 1.40) cells. Moreover, reducing virus activity by fivefold or sixfold logarithmically between the range of 5-10 μg g-1 of 30-year-old gum extracts underscored the biological activity. In ovo antiviral activity studies on the P. lentiscus were conducted for the first time. The mastic gum and leaves obtained from P. lentiscus may have strong potential in terms of their chemical content and antiviral and cytotoxic activity. As a consequence of these properties, it is a sustainable, renewable natural resource that can be used as an additive and flavoring in the food and pharmaceutical industries. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

General Two-Step Method for the Fabrication of Covalent-Organic Framework-Bound Open-Tubular Capillary Columns for High-Resolution Gas Chromatography Separation of Isomers.

Covalent organic frameworks (COFs) are promising as stationary phases for gas chromatography (GC). The successful anchoring of COFs to the inner walls of the capillary with good uniformity is an important prerequisite to ensure the excellent separation performance of columns. However, current methods for the fabrication of COF-based capillary columns cannot always meet this requirement when faced with different COFs, which hampers the further development of COF-based GC stationary phases. Here, we show a general two-step method for the fabrication of COF-bound capillary column. The first step enables the formation of uniform amorphous polymer layer on the inner walls of capillary, while the second step allows the facile transformation of the amorphous polymer layer into a highly crystalline COF layer. COF-bound capillary columns with different framework structures were fabricated successfully by the developed two-step method. Impressively, the COF layers bound on the inner walls of these capillary columns showed good uniformity and high crystallinity. More importantly, as an example, the fabricated Tab-DHTA-bound capillary column showed good resolution (R > 1.5) and high column efficiency (700-39,663 plates m-1) for the tested isomers of ethylbenzene, xylene, dichlorobenzene, chlorotoluene, pinene, 1,3-dichloropropene, and propylbenzene with good precision (RSD, run-to-run, n = 5) (retention time, 0.2-0.6%; peak area, 0.5-1.1%; and peak height, 0.5-1.4%). In general, the fabricated Tab-DHTA-bound capillary column exhibited better performance for the separation isomers than commercial columns DB-5 and HP-FFAP. These results indicate that the two-step method is an efficient way to fabricate the COF-bound capillary column with excellent separation performance.

SAT446 Association of Polychlorinated Biphenyls With the Hormonal Parameters of the Normal Menstrual Cycle May Contribute to Unexplained Infertility

Abstract Disclosure: A.E. Butler: None. E. Brennan: None. T. Sathyapalan: None. S.L. Atkin: None. Introduction: Polychlorinated biphenyls (PCBs) are organic lipophilic pollutants that accumulate through the diet and increase with age and obesity. Previous research has linked PCBs with menstrual function; therefore, this study was undertaken to look at the association of PCBs with parameters of menstrual function at day 21 of the menstrual cycle in a group of women who were undergoing in vitro fertilization (IVF). Methods: 29 Caucasian women from a UK academic center aged 32.9±4.4 years, with body mass index BMI 25.4±3.6 kg/m2, who were undergoing in vitro fertilization were recruited. Five of the women had unexplained infertility and the remainder (n=24) had male factor infertility or tubal problems. Blood was withdrawn at day 21 of their menstrual cycle, at the time of mock embryo transfer. PCBs were measured using high resolution gas chromatography. Results: Only PCB118, PCB153, PCB138 and PCB180 were detected. PCB153, PCB138, PCB180 inversely correlated with estradiol (p&amp;lt;0.05). PCB 118 and PCB138 inversely correlated with FSH (p&amp;lt;0.05). PCB118, PCB153, PCB138 and PCB180 inversely correlated with LH (p&amp;lt;0.05, p&amp;lt;0.01, p&amp;lt;0.01 and p&amp;lt;0.01, respectively). No correlation was seen between PCBs and progesterone. Women with unexplained infertility showed higher levels of PCB118, PCB153, PCB138 and PCB180 (p&amp;lt;0.05) compared to those with male factor infertility though other hormonal parameters did not differ other than FSH that was lower in the unexplained group (p=0.01). Conclusion: These data are in accord with an effect of PCBs on the menstrual cycle in normal women and may be involved in the mechanism of unexplained infertility. Presentation Date: Saturday, June 17, 2023

Exploration of the correlation of serum polychlorinated biphenyl levels with luteal phase hormonal parameters and infertility in women with or without polycystic ovary syndrome.

Polychlorinated biphenyls (PCBs) are organic lipophilic pollutants that accumulate in the body. Previous research has linked PCBs with menstrual function; therefore, this study was undertaken to investigate the correlation of PCBs with luteal phase hormonal parameters of menstrual function at day 21 in a group of non-obese women prior to in vitro fertilization (IVF). Fifty-eight non-obese Caucasian women from a UK academic center, 29 with polycystic ovary syndrome (PCOS) and 29 without, were recruited. PCOS women all had anovulatory infertility. Non-PCOS women: five with unexplained infertility, the remainder with male factor infertility (n=14) or tubal problems (n=10). Blood was withdrawn at day 21 of the menstrual cycle for non-PCOS women, at the time of mock embryo transfer. PCBs were measured using high resolution gas chromatography. Only PCB118, PCB153, PCB138 and PCB180 were detected in all samples, and levels did not differ between PCOS and non-PCOS subjects. In non-PCOS subjects, PCB153, PCB138 and PCB180 inversely correlated with estradiol (p<0.05); PCB118 and PCB138 inversely correlated with follicle stimulating hormone (FSH) (p<0.05); PCB118 (p<0.05), PCB153, PCB138 and PCB180 (all p<0.01) inversely correlated with luteinizing hormone (LH). Control women without PCOS with unexplained infertility showed higher levels of PCB118, PCB153, PCB138 and PCB180 (p<0.05) compared to those control women without PCOS with tubal or male factor infertility, though other hormonal parameters did not differ other than that FSH that was lower in the unexplained group (p=0.01). The only correlation observed in PCOS women with anovulatory infertility was that between PCB180 and progesterone (p<0.05). PCBs correlated with luteal phase menstrual cycle hormones in control women without PCOS and may contribute to the mechanism of unexplained infertility; in PCOS women, no correlations of the PCBs were seen for estradiol, LH or FSH.

The low dose of L-lactic acid as loess soil amendment enhances wheat rhizosphere microecosystem

Loess covers ∼12% of the global continental area. However, soil salinization, due to chemical or physical weathering of rock, overgrazing and inappropriate agricultural practices, etc., threatens the quality of loess and the yield of crops. Exploring sustainable, accessible, and affordable soil amendments is consequently required to upgrade loess soil quality. Herein, L-lactic acid, as the main by-product in the process of biowaste fermentation, has been investigated due to its affordability and accessibility for this purpose. The interactions of L-lactic acid with loess soil and rhizosphere microecosystem were explored to unveil its capacity to ameliorate salinity-related concerns and rejuvenate the agricultural capabilities of the soil. The effects of L-lactic acid addition on soil rhizosphere microorganisms and growth of wheat seedlings were investigated at the L-lactic acid dosages of 0.07–2.99 mg-C/g-soil with determination of the physiological characteristics of wheat seedlings, bulk soil, and rhizosphere microorganisms. The low dose of L-lactic acid (0.07–0.75 mg-C/g-soil) was demonstrated to abate the salt ion content (Na+, K+, and Ca2+) in bulk soil and alleviate the effects of salt stress on plants. By contrast, the addition of a high dose of L-lactic acid (1.49–2.99 mg-C/g-soil) boosted the salt ion content (Na+, K+, and Ca2+) in bulk soil and exacerbated salt stress. In accordance with the K+:Na+ ratio and chlorophyll content indicators of wheat seedlings, a low dose of L-lactic acid enhanced plant photosynthesis and tolerance to salt stress. The L-lactic acid–induced rhizosphere microecosystem established an environment that supported microbial growth with elevated soluble phosphorus levels, which provided the basis for the plant–microbe–soil nutrient cycle and metabolism. Gas chromatography–high resolution Orbitrap mass spectrometry used plant volatile organic compounds (VOC) as the indicators of specific and sensitive signals to reveal that a low dose of L-lactic acid supported the enrichment of VOC in the aerial parts of wheat by heightening plant disease resistance and thereby increasing the aboveground biomass of plants. A high dose of L-lactic acid diminished the K+:Na+ ratio and chlorophyll content in wheat and reduced plant photosynthesis resistance to salt stress; furthermore, the number of disease-resistant VOC available to wheat was curtailed, inhibiting wheat growth. Our study suggests that L-lactic acid added at an appropriate dose can effectively benefit the rhizosphere microecosystem and plant growth, thereby enhancing crop defense and yield. Thus, a soil amendment derived from L-lactic acid demonstrates significant potential in the application for loess soil.