Gas Chromatography-mass Spectrometry Method Research Articles

Multimodal Metabolomics Analysis Reveals That Classic Decoction Mitigates Myocardial Ischemia-Induced Damage by Modulating Energy and Branched-Chain Amino Acid Metabolism.

Gualou-Xiebai-Banxia (GXB) decoction shows potential for treating myocardial ischemia (MI), although its underlying mechanism is not fully understood. In this study, a multimodal metabolomics approach, combining gas chromatography-mass spectrometry (GC-MS) and 1H-NMR, was employed to investigate the cardioprotective effects of GXB in a rat model of myocardial ischemia induced by ligation. ELISA assays and HE staining demonstrated that GXB effectively reduced myocardial injury, oxidative stress markers, and myocardial fibrosis. Orthogonal partial least-squares discriminant analysis identified 62 biomarkers, 20 of which were confirmed using standard compounds. The GC-MS method showed excellent linearity across a wide concentration range (0.004-29.7 μg/mL, R2 > 0.9995), with intra- and inter-day precision RSD values below 4.72% and 4.96%, respectively. Method recoveries ranged from 95.40% to 104.83%, with RSD values under 4.84%. Pathway enrichment analysis revealed that GXB decoction alleviates myocardial ischemia-induced damage primarily by modulating energy metabolism and branched-chain amino acid metabolism. These findings provide valuable support for the clinical application of GXB decoction in treating myocardial ischemia.

Identification of potential biomarkers and pathways involved in high-altitude pulmonary edema using GC-MS and LC-MS metabolomic methods

High-altitude pulmonary edema (HAPE) is a life-threatening altitude sickness afflicting certain individuals after rapid ascent to high altitude above 2500 m. In the setting of HAPE, an early diagnosis is critical and currently based on clinical evaluation. The aim of this study was to utilize the metabolomics to identify the altered metabolic patterns and potential biomarkers for HAPE. Serum samples from HAPE patients (n = 24) and healthy controls (n = 21) were analyzed by gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS) to profile differential metabolites and explore dysregulated metabolic pathways. The correlation analysis and receiver operating characteristic (ROC) curve analysis were further performed to screen biomarkers for HAPE. A total of 119 differential metabolites between the control and HAPE groups were identified. Top dysregulated pathways included pyrimidine metabolism, citrate cycle, sulfur metabolism, phenylalanine metabolism and purine metabolism. After correlation analysis with clinical indices, 39 differential metabolites were obtained as potential biomarkers related to HAPE. Finally, 7 biomarkers, specifically S-nitroso-N-acetylcysteine, aminocaproic acid, emodin, threo-hydroxyaspartic acid, 6-hydroxynicotinic acid, 3-acetylphenol sulfate and cis-aconitic acid, were screened out through ROC analysis, which displayed high diagnostic accuracy for HAPE. Taken together, the altered serum metabolic profile is associated with the occurrence of HAPE. Diagnostic tests based on the biomarkers from metabolomics may hold promise as a strategy for early detection of HAPE.

Establishment, evaluation and application of a gas chromatography-mass spectrometry method for quantification of volatile organic compounds in ambient air using anisole as an internal standard

Gas chromatography coupled with mass spectrometry (GC-MS) is a standard analytical method for identifying specific volatile organic compounds (VOCs) in urban air samples. Quantification ideally relies on calibration curves using standards for each compound. However, due to the variable composition of VOCs and the limited availability of all standards, this strategy is challenging and not always feasible. Quantification using an internal standard is a simple and accurate approach, as it involves the simultaneous analysis of the internal standard and analytes, eliminating the need for a calibration curve if their concentrations fall within the linear dynamic range. In this study, quantification of VOCs from different chemical classes has been evaluated using a single standard mixture and anisole as an internal standard and compared to the external calibration as standard method for quantification by GC-MS. Both methods showed comparable results, with a relative error within ±30% of the theoretical concentration. Linearity was confirmed in the range from 100 to 4000 μg/L, and the relative standard deviation (RSD) of the relative response factors (RRFs) met the acceptance criteria of ≤30% for each target VOC. Toluene, chlorobenzene, C6-C2 and C6-C3 substituted benzenes yielded similar average RRFs, ranging from 1.280 to 1.601 with an RSD of 7.83%. The methods were applied for quantification of VOCs in ambient air on real samples collected on Radiello adsorbents at one urban location. Using anisole as an internal standard proved to be a simple and reliable method for determining VOC concentrations, offering a convenient alternative to external standard calibration.

Chemical composition and potential pharmacological properties of field horsetail extract based on GC-MS analysis

The Equisetaceae family, particularly the species Equisetum arvense (field horsetail), has long attracted the attention of researchers due to its ancient origins and various applications in traditional medicine. Field horsetail has been used to treat inflammation, wounds, infections, and urinary tract diseases. In this study, a phytochemical analysis of the field horsetail extract was conducted using gas chromatography-mass spectrometry (GC-MS) to examine its chemical composition and assess its wound-healing properties. The horsetail extract was obtained through percolation with ethanol, followed by treatment with diethyl ether and chloroform to isolate nonpolar compounds. Final purification of the extract was carried out using aluminum oxide. The GC-MS method revealed a variety of compounds, including terpenes and fatty acids. Among these were components with anti-inflammatory, antibacterial, and antioxidant properties that may aid in accelerating wound healing. The primary components of the extract associated with wound-healing effects include quercetin, kaempferol, and β-sitosterol. The phytochemical analysis confirmed significant antioxidant properties in the extract, which may help protect tissues from oxidative stress that occurs during wound healing. The identified antibacterial compounds may help prevent wound infections and accelerate tissue regeneration. Thus, the field horsetail extract, processed with chloroform and diethyl ether, represents a promising source of bioactive compounds with potential for application in the development of wound-healing agents.

Identification of a novel imidazole-derived GABA agonist isopropoxate: simultaneous detection and quantification of imidazole-derived analogs from human hairs in abused cases by LC-MS/MS.

Distribution and abuse of imidazole-derived γ-aminobutyric acid (GABA) agonists, such as etomidate and metomidate, and their analogs have been encountered frequently especially in China. The aim of this study was to identify etomidate, metomidate, propoxate, and isopropoxate more accurately by establishing a gas chromatography-mass spectrometry (GC-MS) and liquid chromatography tandem mass spectrometry (LC-MS/MS) method and applying it to real forensic cases. Onemg of the seized powder was dissolved in 1mL of methanol, and subjected to GC-MS and LC-MS/MS. Hair samples were washed and cut into approximately 2mm sections, then ground to powder by a low-temperature grinder. Twenty mg of the hair powder was extracted with 1mL of methanol, and the supernatant was subjected to LC-MS/MS. Etomidate, metomidate, propoxate, and isopropoxate were chromatographically separated and each mass spectrum was obtained by GC-MS. For LC-MS/MS, tested validation data were all satisfactory. The seized powder samples contained isopropoxate, with an approximate content of 30.9%. Etomidate, etomidate acid, metomidate, and isopropoxate could be determined in the submitted hairs, ranging from 2.89 to 8.09ng/mg, 0.0591-0.177ng/mg, 0.342-2.77ng/mg, and 33.2-130ng/mg, respectively. Mass spectra and ion chromatograms of etomidate, metomidate, isopropoxate, and propoxate were obtained by GC-MS. We have also established a simultaneous and reliable analytical method for etomidate, etomidate acid, metomidate, and isopropoxate in human hair by LC-MS/MS. This is the first report to present analytical results of a novel imidazole-derived GABA agonist isopropoxate in drug abuse cases.

Plant-part chemical composition of essential oils of Crithmum maritimum L. from Montenegro

This paper reports the chemical constituents of essential oils from different organs of Crithmum maritimum L. collected at three localities in Montenegro (Bar, Budva and Herceg-Novi), thus covering the northern, central and southern parts of the national coastline. A total of 12 samples were isolated by hydrodistillation and analysed by gas chromatography–mass spectrometry method. The highest yield was observed in fruits, while rhizomes contained the lowest amount of essential oil. The high content of monoterpene hydrocarbons, such as limonene and γ-terpinene, characterised the samples from leaves, fruits, and flowers. Essential oils obtained from rhizomes were characterised by phenylpropanoids dillapiole and elemicin. Depending on the plant organ and locality, four different chemotypes can be distinguished. This is the very first report on essential oils of C. maritimum L. leaves, flowers, and fruits collected in Montenegro.

Bioactive Components and Bacteriological potentials of Acacia nilotica Leaves’ Extract

Medicinal plants have been recognized as valuable source of natural antibacterial compounds and alternative agent for the treatment of bacterial infections. This study was carried out to determine the phytochemical properties, antibacterial activity and biochemical compounds of the crude extracts of Acacia nilotica. The reflux extraction, qualitative phytochemical screening, agar well diffusion and gas chromatography mass spectrometry (GC-MS) method was used. Phytochemical screening indicates the presence of phytochemicals such as alkaloids, tannins, saponins, phenols, sterols, terpenoids and flavonoids. Ethyl acetate and aqueous extracts were the most active with mean inhibition zone (MIZ) diameter of 20.00±0.00mm and 14.67±1.16mm against B. cereus and P. aeruginosa respectively while the MIZ of the fractions (22.00±1.53mm) were higher at 50mg/mL as compared to the positive control with MIZ of 17.00±0.00 (p<0.05). the lowest minimum inhibitory concentration (MIC) and minimum bactericidal concentration MBC of 15.6mg/mL and 31.3mg/mL were obtained against P. aeruginosa. Compounds identified in the most active fractions with higher peaks include Oleic Acid (24.43%), n-Hexadecanoic acid (22.96%) and Tetradecanetetrol (19.25%) which are reported to possessing antibacterial activity. Based on the result of this study, it can be concluded that extract from Acacia nilotica possess antibacterial activity and can be considered for drug development against the test organisms.

Fluorotelomer Alcohol (FTOH) Emission Rates from New and Old Rain Jackets to Air Determined by Iodide High-Resolution Chemical Ionization Mass Spectrometry

Per- and polyfluoroalkyl substances (PFAS), which include fluorotelomer alcohols (FTOHs), are synthetic chemicals used in consumer products because of their water-, stain-, and grease-repellent properties; thus, PFAS are commonly found in functional clothing such as rain jackets. To date, emissions of PFAS from products to indoor air have not been well characterized, although many PFAS-containing products are used and stored indoors. We used a test chamber connected to a high-resolution time-of-flight chemical ionization mass spectrometer equipped with iodide as a reagent ion (I-HR-ToF-CIMS) to measure emission rates for four FTOHs from 10 rain jackets and one backpack cover. The materials were categorized as old/used, new, or “PFAS-free”, and they were tested under two different scenarios, i.e., immediately out of package and after airing out. We observed real-time FTOH emissions from all materials. Under the out-of-package scenario, emissions of 6:2, 8:2 and 10:2 FTOH showed characteristics that indicate mass transfer is limited by internal diffusion, with a high initial peak followed by a lower steady-state emission rate. Peak emission rates correlated well with material-phase concentrations determined by an offline extractive gas chromatography-mass spectrometry (GC-MS) method. Our results further suggest that the old, used jackets had, on average, higher peak emission rates and higher material-phase concentrations than the new jackets, largely driven by 8:2 FTOH. “PFAS-free” materials had the overall lowest emission rates and material-phase concentrations. After airing out, emission rates were on average an order of magnitude lower than peak emission rates. Our findings emphasize the importance of considering consumer products like rain jackets as sources of indoor exposure to PFAS.

Analysis and Characterization of Pericopsis mooniana Seed Oil for Potential Applications in Cosmetics and Nutritional Supplements

Pericopsis mooniana is renowned for wood applications, while its bark and leaves find uses in ayurvedic medicine. The shifting of global cosmetic and nutritional supplement industries towards plant-based oils has led to explore novel sources. No prior studies were done on P. mooniana seed oil. Therefore this study aims to characterize the seed oil of P. mooniana by determining Fatty Acids (FA) composition as their methyl esters, nonpolar constituents in unsaponifiable matter, and other physio-chemcial properties. The oil was extracted using the soxhlet extraction method. Ash and moisture contents of seeds, Acid Value (AV), Iodine Value (IV), smoke point and thermal stability of oil were also determined. Prepared fatty acid methyl esters and chemical constituents in unsaponifiable matter were identified and quantified using Gas Chromatography-Mass Spectrometry method. Results indicated a substantial oil yield of 36.71± 0.01% with moisture content of 5.60 ± 0.19%, ash content of 3.65 ± 0.38%, AV of 2.97 ± 0.40 mg KOH/g, IV of 16.02 ± 0.14 g I2/100g, smoke point of 233.6 ± 8.57°C, decomposition temperature of 409.95 ± 1.74°C and yield of unsaponifiable matter of 1.35 ± 0.01%. The dominant FAs are oleic (41.02%) and linoleic (38.12%) acids. Major unsaponifiable matter constituents are squalene (4.01 mg/g), beta.-sitosterol (2.63 mg/g), stigmasterol (1.23 mg/g), phytol (1.45 mg/g), geranylgeraniol (1.03 mg/g) and amyrin (0.95 mg/g). Based on the finding of this study, it can be concluded that P. mooniana seed oil has the potential to be utilized in both cosmetic and nutritional supplement industries.

Potential Molecular Mechanisms and Metabolic Networks in Red Ginseng-induced “Shanghuo” (上火)

Objective: To comprehensively uncover potential molecular mechanisms and metabolic networks in RG-induced “ Shanghuo”. Red ginseng (RG) could bring out the manifestations of “ Shanghuo”, which mostly presents as redness, swelling, fever, and pain. Methods: The compounds of RG were obtained from the TCMSP and SymMap databases. The putative targets of RG were determined based on the obtained compounds by STITCH. The potential targets of “ Shanghuo” were retrieved from the literature. Those interacted targets of RG and “ Shanghuo” were screened by STRING and conducted networks of RG and “ Shanghuo”. The RG-influenced “ Shanghuo” targets were further analyzed by the STRING and proved by molecular docking. Afterwards, water extract of RG was given to 6 weeks-old rats for 15 days. Observations were carried out to confirm the establishment of “ Shanghuo” model. Gas chromatography-mass spectrometry (GC-MS) were utilized to identify the differential metabolites. Results: Apolipoprotein B and Serum albumin (ALB) were the co-acting targets, while Transient Receptor Potential Channel Vanilloid 1 was a vital target of RG jointing “ Shanghuo” and RG together through the connection via ALB. Ginsenoside Rb1 was the most influential compound of RG to induce “ Shanghuo” by molecular docking. Our study indicated that fat digestion and absorption and cholesterol metabolism the potential mechanism of RG-induced “ Shanghuo”. An acceleration of energy expenditure in the “ Shanghuo” group was additionally verified by conducting the GC-MS method. Conclusion: The disorders in heat dissipation along with the accelerated fat metabolism and overactive energy expenditure might contribute to RG-induced “ Shanghuo”.

Desorption efficiency and holding capacity of acid-treated filters for nicotine sampling in vape shops.

Efficient sampling materials are essential for assessing nicotine levels in vape shops and other settings where nicotine exposures may exist. Two different treatments of Whatman glass fiber type A (GF/A) filters (sodium bisulfate treated and citric acid treated) were evaluated for nicotine capture, desorption efficiency, and holding capacity using Gas Chromatography-Mass Spectrometry (GC-MS). The Filters were treated with 0.8mL of 0.1 M sodium bisulfate or citric acid solution and oven-dried (80 °C) for 30min. Nicotine was desorbed off the filters using a modified analytical method. The average nicotine desorption efficiency for sodium bisulfate-treated GF/A filters (98.4%) was significantly higher than that of citric acid-treated GF/A filters (60.9%) over a range of 1-100 µg nicotine. Sodium bisulfate-treated and citric acid-treated GF/A filters experienced a 10% nicotine breakthrough after being dosed with about 550 and 2,750 µg of nicotine, respectively compared to 75 µg for untreated GF/A filters. Citric acid-treated GF/A filters had a much greater nicotine-holding capacity, but nicotine desorption from citric acid-treated GF/A filters was below the recommended criteria. Therefore, we recommend that sodium bisulfate-treated GF/A filters are employed for sample of nicotine with the GC-MS method.

B-168 Development and Validation of a Quantitative Ultra-Performance Liquid Chromatography Quadrupole Time-of-Flight (UPLC-QToF) Method for Urine Organic Acid Analysis

Abstract Background Urine organic acid (UOA) analysis is essential for the diagnosis of inborn errors of metabolism (IEMs). Traditionally, UOA analysis is performed with gas chromatography-mass spectrometry (GC-MS) and requires time-consuming sample preparation steps including liquid-liquid extraction and derivatization. The rapid development of Ultra-Performance Liquid Chromatography Tandem Mass Spectrometry (UPLC-MS/MS) in the past few years provides the opportunity to perform UOA analysis with a dilute-and-shoot methodology. We describe the development and validation of a quantitative Ultra-Performance Liquid Chromatography Quadrupole Time-of-Flight (UPLC-QToF) method for UOA analysis. Methods Urine specimens were diluted to normalize creatinine concentrations to 1 mmol/L. 20 µL of urine specimen (diluted), calibrator, or quality control (QC) material was mixed with 400 µL of mobile phase A (0.05% formic acid in water) and a mixture of isotope-labeled internal standards. After centrifugation, 10 µL of the supernatant was analyzed using a Xevo G3 QTOF mass spectrometer (Waters) with a ACQUITYTM Premier HSS T3 1.8 µm VanGuardTM FIT 2.1 x 150 mm column (Waters). Data collection was performed with negative electrospray ionization (ESI) mode using the MSE method to produce fragment ions when applicable. Repeatability, reproducibility, and carryover were assessed using the QC materials. The analytical measuring range (AMR) was assessed using synthetic urine spiked with increasing concentrations of each organic acid. Accuracy was assessed by method comparison with the UOA test performed at Mayo Clinic Laboratory and by spike-recovery study using a pooled urine specimen. Matrix effect was also evaluated with matrix dilution study. Results An optimized LC method was used to enable high-resolution separation of selected UOAs (N = 29) and isomers. Total analytical time was 20 min per injection. Both linear and quadratic regressions were used to build the calibration curves. AMR and correlation coefficients of a few representative UOAs were: orotic acid (3.4 to 214.2 mmol/mol creatinine, R^2 = 0.99, linear regression); 2-methylcitric acid (4 to 189 mmol/mol creatinine, R^2 = 0.99, linear regression); 3-methylcrotonylglycine (0.3 to 18.0 mmol/mol creatinine, R^2 = 0.99, linear regression). Repeatability and reproducibility were mostly <=10% CV and no carryover was observed. Spike-recovery study demonstrated recoveries between 80% and 120%, and method comparison study demonstrated no discrepancies with results from Mayo Clinic Laboratory. Conclusions We have developed and validated a novel UPLC-QTOF method for UOA analysis to support the diagnosis of IEMs with acceptable analytical and clinical performances. Compared with the traditional GC-MS method, the UPLC-QTOF method requires a very small specimen volume and does not require laborious and time-consuming sample preparation steps. Continued optimization of the method will be pursued to measure more UOAs to support the diagnosis of more IEMs.

A GC-MS Method for Determination of β-Propiolactone Residues in Inactivated Covid-19 Vaccines.

β-propiolactone is a common inactivator agent used in vaccines. Due to β-propiolactone carcinogenicity, complete hydrolysis of it is necessary to prevent cytotoxicity in mammalian cells. As a result, more attention should be paid to it at the clinic, and it is important to measure its trace amounts. β-propiolactone analysis is challenging due to its instability. A simple and fast gas chromatography-mass spectrometry method was developed for quantitation of residual β-propiolactone in inactivated coronavirus disease 2019 (Covid-19) vaccines. Caprolactone was used as an internal standard in sample solutions; the analysis was performed after extraction of analyte from vaccine media by ethyl acetate. The validity of the method was studied with a linearity of r2> 0.99 over the concentration range of 0.2-20μg/mL with the limit of detection and the limit of quantification of 0.07 and 0.20μg/mL, respectively. The target analyte β-propiolactone was not detected in the samples, demonstrating the test samples were qualified. The established method can be used for quality control of inactivated Covid-19 vaccines.

The optimization and validation of a gas chromatography-mass spectrometry method to analyze the concentration of acetate, propionate and butyrate in human plasma or serum

Fermentation-derived short-chain fatty acids (SCFA)44SCFA: short-chain fatty acids. are potential mediators of the health benefits associated with dietary fiber intake. SCFA affect physiological processes locally in the gut and on distant organs via the systemic circulation. Since SCFA are used as energy source for colonocytes and substrate for the liver metabolism, their concentrations in the systemic circulation are low. Therefore, quantification of systemic SCFA requires sensitive analytical techniques. This article covers the optimization and validation of a gas chromatography-mass spectrometry method to measure systemic SCFA concentrations following derivatization with 2,4-difluoroaniline (DFA)55DFA: 2,4-difluoroaniline. and extraction in ethyl acetate. Sample preparation was optimized by varying the amount of DFA, coupling agent 1,3-dicyclohexylcarbodiimide, ethyl acetate and sodium bicarbonate, which is used to quench derivatization. In addition, evaporation of the samples using a vacuum concentrator resulted in less contamination, notably of acetate, compared to drying with N2 gas. The method showed excellent linearity with coefficient of variation (R2) > 0.99 and a good precision (relative standard deviation < 20 %) and accuracy. Finally, systemic concentrations of SCFA in human plasma samples could successfully be determined.

GC-MS validation and analysis of targeted plasma metabolites related to carbonyl stress in type 2 diabetes mellitus patients with and without acute coronary syndrome.

Methylglyoxal (MG) is responsible for advanced glycation end-product formation, the mechanisms leading to diabetes pathogenesis and complications like acute coronary syndrome (ACS). Sugar metabolites, amino acids and fatty acids are possible substrates for MG. The study aimed to measure plasma MG substrate levels using a validated gas chromatography-mass spectrometry (GC-MS) method and explore their association with ACS risk in type 2 diabetes mellitus (T2DM). The study included 150 T2DM patients with ACS as cases and 150 T2DM without ACS as controls for the analysis of glucose, fructose, ribulose, sorbitol, glycerol, pyruvate, lactate, glycine, serine, threonine, C16:0, C16:1, C18:0, C18:1, C18:2, C18:3, C20:0 and C22:6 by GC-MS. Validated GC-MS methods were accurate, precise and sensitive. Cases significantly differed in plasma MG and metabolite levels except for lactate, C16:0, C18:0, C18:2, and C18:3 levels compared with controls. On multivariable logistic regression, plasma C20:0, C18:1, glycine and glycerol levels had increased odds of ACS risk. On multivariate receiver operating characteristic analysis, a model containing plasma C20:0, C16:1, C18:1, C18:2, serine, glycerol, lactate and threonine levels had the highest area under the curve value (0.932) for ACS diagnosis. In conclusion, plasma C20:0, C16:1, C18:1, glycine, glycerol and sorbitol levels were associated with ACS risk in T2DM.

Contamination of Phthalic Acid Esters (PAEs) in Surface Sediment Samples Collected from Rao Cai River in Ha Tinh, Vietnam

In this report, the solid phase extraction technique combined with the gas chromatography-mass spectrometry method (GC-MS) was optimized to determine the contamination of nine phthalic acid esters (PAEs) in the surface sediment samples collected from Rao Cai River in Ha Tinh, Vietnam. The method detection limits (MDLs) were from 2.0 to 6.0 ng/g-dry weight (ng/g-dw). The recoveries of surrogate standards (PAE-d4) in both blank and real samples ranged from 79.6 to 94.3% (RSD &lt; 8.7%). The total concentration of PAEs in the surface sediment samples was in the range of 72.4-1390 ng/g-dw (mean/median: 561/552 ng/g-dw). Among PAEs, di-(2-ethyl)hexyl phthalate (DEHP) was detected at the highest level in all samples. In contrast, dimethyl phthalate (DMP), diethyl phthalate (DEP), and dipropyl phthalate (DPP) were found at low frequency and concentration. Moreover, the risk quotient of PAEs in sediments was estimated based on the measured concentrations. Diisobutyl phthalate (DiBP) posed a medium risk for fish.

Enhanced differentiation between 3-hydroxyglutaric and 2-hydroxyglutaric acids facilitates diagnostic testing for glutaric aciduria type 1.

Glutaric aciduria type 1 (GA1) is an inherited neurometabolic disorder, in which deficiency of glutaryl-CoA dehydrogenase leads to accumulation of glutaric acid (GA) and 3-hydroxyglutaric acid (3-HG). Some low excretors may exhibit only slight elevation of urinary 3-HG, with normal urinary GA, yet are at significant risk of severe clinical disease. Accurate quantitation of urinary 3-HG is crucial in diagnostic workup for GA1, but in this context, current gas chromatography-mass spectrometry (GC-MS) methods have inherent analytical challenges. Co-elution and spectral similarities of the 3-HG and 2-HG structural isomers can cause difficulties in quantitation of slightly elevated 3-HG. Our laboratory recently acquired a gas chromatography system coupled to a triple quadrupole mass spectrometer (GC-MS/MS), and we took advantage of its increased sensitivity and specificity to improve our existing GC-MS method. A stable isotope dilution process is used, with sample treatment consisting of a double liquid-liquid extraction followed by a trimethylsilyl derivatization. The transitions m/z 349 → 333 for 3-HG and m/z 349 → 321 for 2-HG were selected to differentiate these two isobaric molecules based on their characteristic fragments, thus minimizing interferences despite co-elution. Method validation demonstrated satisfactory precision and accuracy. Using GC-MS/MS instead of GC-MS allowed us to decrease the required specimen volume, number of sample processing steps, chromatographic run time, and instrument maintenance. This enhanced assay facilitates clinical laboratory testing for GA1, both in confirmatory protocols following positive newborn screening and in diagnostic investigation of patients with suggestive signs or symptoms.

Microbial Community Dynamics and Metabolite Changes during Wheat Starch Slurry Fermentation.

Wheat starch fermentation slurry is the main substrate for producing Ganmianpi, a traditional Chinese fermented wheat starch-based noodle. In the present work, the microbial population dynamics and metabolite changes in wheat starch fermentation slurry at different fermentation times (0, 1, 2, 3, and 4 days) were measured by using high-throughput sequencing analysis and headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME/GC-MS) methods. The texture and sensory properties of Ganmianpi made from fermented starch slurry are also evaluated. The results showed that Latilactobacillus curvatus and Leuconostoc citreum were the dominant bacteria in wheat starch fermentation slurry, while Saccharomyces cerevisiae and Kazachstania wufongensis were identified as the main species of fungi. With the extension of fermentation time, the reducing sugar content first increased and then decreased, when the titratable acidity content showed an increasing trend, and the nonvolatile acid was significantly higher than the volatile acid. A total of 62 volatile flavor compounds were identified, and the highest content is alcohols, followed by acids. Fermentation significantly reduced the hardness and chewiness of Ganmianpi, and increased its resilience and cohesiveness. Ganmianpi made from fermented starch slurry for two and three days showed a higher sensory score than other samples. The present study is expected to provide a theoretical basis for exploiting the strains with potential for commercial application as starter cultures and quality improvement of Ganmianpi.

The influence of cancer on the reprogramming of lipid metabolism in healthy thyroid tissues of patients with papillary thyroid carcinoma.

Over the years we observed changes in the metabolism of glucose, amino acids, fatty acids (FA) and nucleotides in cancer cells in order to maintain their viability and proliferate. Moreover, as the latest data show, cancer also forces a complete change in the behavior of other tissues. For instance, fat-filled adipocytes are often found in the vicinity of invasive solid human tumors. We investigated the effects of papillary thyroid carcinoma (PTC) on the lipid metabolism of healthy tissue distant from the tumor. Thyroid tissue was collected from female patients immediately after surgical removal of the entire thyroid gland. Blood samples were collected from PTC patients and healthy volunteers. Real-time PCR assays were performed to analyze the expression of lipogenic genes and a broad panel of FA was determined using the gas chromatography-mass spectrometry method. The concentration of lipids was higher in paratumor tissue than in healthy thyroid tissue (p = 0.005). The lipogenic genes tested were significantly increased in paratumor tissue compared to healthy tissue, especially enzymes related to the synthesis of very long-chain saturated and polyunsaturated FAs (VLCSFAs and PUFAs, respectively) (p < 0.001). The FA profile also showed increased levels of C22-C26, VLCSFAs and almost all PUFAs in paratumor tissue (p < 0.05). Our study suggests that a restructuring of lipid metabolism occurs in the adjacent healthy thyroid gland and that the metabolism of VLCSFAs and PUFAs is higher in the paratumor tissue than in the distant tissue of the healthy thyroid gland.

Identification and health risk assessment of volatile and semi-volatile migrants along with chemical elements in food contact water-borne coating paper

Water-borne coating paper, with its food contact potential, raises concerns due to unknown contaminants. Herein, the presence and migration of volatile and semi-volatile compounds, along with chemical elements from two water-borne coating paperboards were investigated using 4 % acetic acid, 50 % ethanol, and 95 % ethanol, while also evaluating associated health risks. The results showed that the overall migration to 95 % ethanol from both papers indicated the non-compliance with the reference limit of 10 mg/dm2. Utilizing an optimized direct immersion-solid-phase microextraction coupled to gas chromatography-mass spectrometry method, a total of 66 migrants were identified, among which 16 and 7 were classified as Cramer Ⅲ and Cramer Ⅱ, respectively, linked to coating and paper raw materials. Additionally, 28 chemical elements released from papers were analysed using inductively coupled plasma mass spectrometry, where higher levels of elements (i.e., Na, K) were observed in the migration of 4 % acetic acid, potentially from additives or raw materials used in papermaking processes. More importantly, health risk assessment based on the Threshold of Toxicological Concern approach or worst-case dietary intake assumption indicated that, the estimated daily intake of most migrants and chemical elements through human exposure fell below toxicological reference values. However, certain migrants (e.g., 2-ethylhexyl acrylate, methyl benzoate, phenanthrene, and longifolene) exhibited concerning migration levels in 50 % ethanol and 95 % ethanol that exceed their safety thresholds and may pose health risks. Overall, understanding the migration and potential risk of migrants are imperative for ensuring the safety of using commercially available water-borne coating paper in food contact applications.