Phase Microextraction-gas Chromatography-mass Spectrometry Research Articles

Dynamic changes of 3-MCPD esters and glycidyl esters contents as well as oil quality during repeated deep-frying

In this study, the dynamic changes of 3-monochloropropane-1,2-diol esters (3-MCPDEs) and glycidyl esters (GEs) in both oils and French fries were assessed using headspace–solid phase microextraction–gas chromatography–mass spectrometry over the course of 5 days repeated deep-frying. The color parameter, as well as the concentrations of tocopherols and total polar components (TPC) in frying oils, were also evaluated. The content of 3-MCPDEs in frying oil reduced by 71.2% in the first two days of frying while GEs increased steadily. The concentration of 3-MCPDEs in French fries increased over the repeated frying while GEs and oil uptake maintained constant. The concentration of tocopherols decreased while TPC increased significantly during repeated deep-frying. Microstructure analysis of French fries by X-ray micro-computed tomography (micro-CT) indicated the reduction of micropores and the appearance of bigger oil-filled macropores, which might be responsible for the enrichment effect of French fries on 3-MCPDEs and GEs. This research broadens the understanding of the fate of 3-MCPDEs and GEs in repeated deep-frying.

Study on the Effect of Jujube Powder on the Quality of Bread

As a traditional Chinese medicine and food, jujube is rich in minerals, dietary fiber, polysaccharides, vitamins and other healthy nutrients, which are the supplemental nutrition to wheat flour. This paper studied the bread quality with jujube powder and determined the appropriate ratio of jujube powder to wheat flour. The related characteristics of bread with jujube powder were analyzed by Electronic nose (E-nose), solid phase micro-extraction gas chromatography-mass spectrometry (SPME-GC-MS), scanning electron microscope, texture analyzer, and Sensory Texture Evaluation Methodology, respectively. The total phenolic content and antioxidant activity of the finished bread were evaluated. The results showed that with the increase of the addition of jujube powder, the specific volume, moisture content and elasticity of bread decreased gradually, while the softness and chewiness were increased progressively. The total phenol content and antioxidant activity of bread increased gradually with the adding of jujube powder content. The bread quality was the best when the addition of 4g of jujube powder/100g of wheat flour. While new volatile substances of jujube bread included hexane, 2, 3-dihydro-3, 5-dihydroxy-6-methyl-4H-phyran-4-one, n-Hexadecane, and l- Caryophyllene, as well as alcohol. Microstructural analysis showed that the structure of stomata changed significantly with the adding of jujube powder. The size of stomata and density of bread are not significantly different from those of ordinary bread with less than 4% jujube powder.

Impact of volatile organic compounds (VOCs) from acrylic double-sided pressure-sensitive adhesives (PSAs) on metals found in cultural heritage environments

An artificial aging protocol known as the Oddy test was combined with headspace solid phase micro-extraction (SPME) gas chromatography-mass spectrometry (GC–MS) data to identify which of 17 double-sided acrylic pressure-sensitive adhesives (PSAs) were safest to use in cultural heritage environments. Traditional Oddy testing showed every PSA corroded lead coupons while 1 also corroded copper and silver coupons. 10 PSAs were suitable for short-term use near cultural heritage artifacts while the remaining 7 were unsuitable. An adapted Oddy test identified whether several known acrylic-based adhesive precursor chemicals, including ethyl acrylate, n‑butyl acrylate, 2-ethylhexyl acrylate, acrylic acid, and abietic acid caused the observed corrosion. Lead coupons were extremely sensitive to acrylic acid, with a 5 × 10−5 mg L-1 Oddy test jar concentration capable of initiating corrosion at 60 °C and 50% RH. SPME GC–MS showed that any evidence of acrylic acid or acetic acid with peak areas larger than 19 million were both markers for unsuitable PSAs. 2-ethylhexyl acrylate was less reactive to metals though a GCMS peak area greater than 200 million was correlated with unsuitable PSAs. 3M™ 465, 3M™ 908, and Tesa® 88,250 tapes were concluded to be the best double-sided PSAs for use in cultural heritage environments.

Chemical and Antimicrobial Analyses of Juniperus chinensis and Juniperus seravschanica Essential Oils and Comparison with Their Methanolic Crude Extracts

Juniperus chinensis and Juniperus seravschanica are commonly used in the traditional folk medicine to treat microbial infection. In this study, the essential oils obtained from the leaves of J. chinensis growing in Malaysia and J. seravschanica growing in Oman were analysed by head space-solid phase microextraction-gas chromatography mass spectrometry (HS-SPME-GC-MS) and screened for antimicrobial activities against Escherichia coli (NCTC 10418), Pseudomonas aeruginosa (NCTC 10662), Bacillus subtilis ATCC6059, Micrococcus luteus (ATCC 9341), Staphylococcus aureus (NCTC 6571), and methicillin-resistant S. aureus (MRSA; ATCC 33591). To compare the antimicrobial activities of extracts using different extraction methods, methanol extraction was performed to obtain crude extracts from the leaves of J. chinensis and J. seravschanica for antimicrobial analysis. The HS-SPME-GS-MS analysis of the essential oils from the leaves of J. chinensis and J. seravschanica identified 37 and 36 components, respectively. Essential oils from these two species had distinctive chemical component profiles, with α-pinene (27.2%) as the major component of J. chinensis essential oil, while dl-limonene (45.2%) constitutes the major component of J. seravschanica essential oil. Essential oils of these two species shared only six similar terpenoids compounds: α-pinene, β-pinene, γ-elemene, sabinene, elemol, and 3-cyclohexen-1-ol. Overall, the essential oils showed antimicrobial activities against all the six bacterial strains tested, with the highest antagonistic activity against M. luteus and B. cereus; while, methanolic crude extracts showed the highest activities against S. aureus and MRSA strains. The methanolic crude extracts demonstrated significantly higher antibacterial activity against the Gram-positive bacteria (p < 0.005); while, the essential oils of Juniperus did not show significant differences between Gram-positive and Gram-negative bacteria. Future studies are needed to investigate the active compounds present in the essential oils and methanolic crude extracts that confer the selectivity in the antimicrobial activity.

Production and recovery of volatile compounds from fermented fruit by-products with Lacticaseibacillus rhamnosus

In the last years, due to the increasing interest of consumers in natural products, market and industry choices were more directed towards the use of fragrances and flavors obtained from natural sources. Fermentation is a biological approach helpful to produce diverse aromatic compounds modifying precursors present in raw material, due to a wide array of extracellular enzymes which could be produced by microorganisms. Following this direction Lacticaseibacillus rhamnosus was employed as a starter for melon and orange by-products fermentation. Simple and vacuum distillation were applied for the recovery of the aromatic fraction and compared to identify the more promising in terms of aromatic profile composition. Detection and characterization of aromatic compounds were achieved using Head SpaceSolid Phase MicroExtraction Gas Chromatography–Mass Spectrometry (HS-SPME/GC–MS) approach. Fermentation led to interesting changes, increasing floral, herbal green and fruity notes. Overall, simple distillation allowed the greater recovery of aromatic compounds in terms of concentration for both substrates. This study highlights a possible strategy to produce complex distillates, composed of a mixture of aroma compounds, to be employed as additives in food, feed or perfumery industries as ingredients of natural origin.

Comprehensive SPME-GC-MS Analysis of VOC Profiles Obtained Following High-Temperature Heating of Pork Back Fat with Varying Boar Taint Intensities.

Boar taint detection is a major concern for the pork industry. Currently, this taint is mainly detected through a sensory evaluation. However, little is known about the entire volatile organic compounds (VOCs) profile perceived by the assessor. Additionally, many research groups are working on the development of new rapid and reliable detection methods, which include the VOCs sensor-based methods. The latter are susceptible to sensor poisoning by interfering molecules produced during high-temperature heating of fat. Analyzing the VOC profiles obtained by solid phase microextraction gas chromatography–mass spectrometry (SPME-GC-MS) after incubation at 150 and 180 °C helps in the comprehension of the environment in which boar taint is perceived. Many similarities were observed between these temperatures; both profiles were rich in carboxylic acids and aldehydes. Through a principal component analysis (PCA) and analyses of variance (ANOVAs), differences were highlighted. Aldehydes such as (E,E)-nona-2,4-dienal exhibited higher concentrations at 150 °C, while heating at 180 °C resulted in significantly higher concentrations in fatty acids, several amide derivatives, and squalene. These differences stress the need for standardized parameters for sensory evaluation. Lastly, skatole and androstenone, the main compounds involved in boar taint, were perceived in the headspace at these temperatures but remained low (below 1 ppm). Higher temperature should be investigated to increase headspace concentrations provided that rigorous analyses of total VOC profiles are performed.

Characterization of Volatile Compounds in Ten Different Instant Noodle Seasonings by Gas Chromatography–Mass Spectrometry and Odor Activity Values

The dominant volatile organic components (VOCs) of ten instant noodle seasonings from three manufacturers were investigated by headspace-solid phase microextraction (HS-SPME) gas chromatography-mass spectrometry (GC-MS). A total of 174 VOCs were identified, including hydrocarbons (8), terpenes (66), aldehydes (16), esters (23), alcohols (17), ethers (8), acids (5), phenols (5), ketones (12), and other compounds (14). Among them, 69 VOCs were identified as significant odorants with odor activity values (OAVs) greater than 1, indicating that these components were important in the distinct seasoning aromas. Linalool, (E,E)-2,4-decadienal, isovaleraldehyde, D-limonene and anethole were found in all samples as dominant aroma compounds. Moreover, the principal volatile compounds responsible for specific seasoning aromas were identified by principal component analysis (PCA) and cluster analysis (CA). The results clearly distinguished four groups of compounds producing the dominant aromas in the ten instant noodle seasonings: group I in spicy beef; group II in stewed chicken with mushrooms; group III in hot beef; and group IV in sour bean and ribs, sour and hot beef, stewed beef, beef with rattan pepper, beef with pickled cabbage, fish and shrimp, and tomato sauce. This study provided a theoretical basis for understanding the aroma characteristics of different flavor instant noodle seasonings.

Trichoderma spp. volatile organic compounds protect grapevine plants by activating defense-related processes against downy mildew.

Volatile organic compounds (VOCs) are produced by soil‐borne microorganisms and play crucial roles in fungal interactions with plants and phytopathogens. Although VOCs have been characterized in Trichoderma spp., the mechanisms against phytopathogens strongly differ according to the strain and pathosystem. This study aimed at characterizing VOCs produced by three Trichoderma strains used as biofungicides and to investigate their effects against grapevine downy mildew (caused by Plasmopara viticola). A VOC‐mediated reduction of downy mildew severity was found in leaf disks treated with Trichoderma asperellum T34 (T34), T. harzianum T39 (T39), and T. atroviride SC1 (SC1) and 31 compounds were detected by head space‐solid phase microextraction gas chromatography–mass spectrometry. Among the Trichoderma VOCs annotated, α‐farnesene, cadinene, 1,3‐octadiene, 2‐pentylfuran, and 6‐pentyl‐2H‐pyran‐2‐one reduced downy mildew severity on grapevine leaf disks. In particular, 6‐pentyl‐2H‐pyran‐2‐one and 2‐pentylfuran increased the accumulation of callose and enhanced the modulation of defense‐related genes after P. viticola inoculation, indicating an induction of grapevine defense mechanisms. Moreover, 6‐pentyl‐2H‐pyran‐2‐one activated the hypersensitive response after P. viticola inoculation, possibly to reinforce the grapevine defense reaction. These results indicate that Trichoderma VOCs can induce grapevine resistance, and these molecules could be further applied to control grapevine downy mildew.

Accurate and sensitive determination of hydroxychloroquine sulfate used on COVID-19 patients in human urine, serum and saliva samples by GC-MS

A rapid, accurate, and sensitive analytical method, ultrasonication-assisted spraying based fine droplet formation–liquid phase microextraction–gas chromatography–mass spectrometry (UA-SFDF-LPME-GC-MS), was proposed for the determination of trace amounts of hydroxychloroquine sulfate in human serum, urine, and saliva samples. To determine the best extraction strategy, several liquid and solid phase extraction methods were investigated for their efficiencies in isolation and preconcentration of hydroxychloroquine sulfate from biological matrices. The UA-SFDF-LPME method was determined to be the best extraction method as it was operationally simple and provided accurate results. Variables such as the extraction solvent, spraying number, sodium hydroxide concentration and volume, sample volume, mixing method, and mixing period were optimized for the proposed method using the one-variable-at-a-time approach. In addition, Tukey's method based on a post hoc comparison test was employed to evaluate the significant difference between the parameters inspected. After the optimization studies, the limit of detection (LOD) and limit of quantification (LOQ) were determined to be 0.7 and 2.4 μg/kg, respectively. The sensitivity of the GC-MS system based on the LOD was enhanced approximately 440-fold when the UA-SFDF-LPME method was employed. Spiking experiments were also conducted for the human serum, urine, and saliva samples to determine the applicability and accuracy of the proposed method. Recoveries for the human serum, urine, and saliva samples were found to be in the ranges of 93.9%–101.7%, 95.2%–105.0%, and 93.1%–102.3%, respectively. These results were satisfactory and indicated that the hydroxychloroquine sulfate level in the above biological samples could be analyzed using the proposed method.

The succession and correlation of the bacterial community and flavour characteristics of Harbin dry sausages during fermentation

This study was to investigate the succession of the bacterial community in Harbin dry sausages during fermentation and its correlation to the sausage flavour. The results showed that Staphylococcus count increased but the moisture content and water activity decreased (P < 0.05). The lactic acid bacteria count first increased and then decreased, while the pH showed an opposite trend during a twelve-day fermentation (P < 0.05). According to a single molecule real time sequencing analysis, Lactobacillus sakei and Staphylococcus xylosus were the predominant bacterial species over the entire fermentation period. A total of 79 volatile compounds were detected using the headspace solid phase microextraction gas chromatography-mass spectrometry. Furthermore, the correlation between the core bacteria (top 30) and the major volatile compounds was explored, which highlighted that three bacterial species (Lb. sakei, S. xylosus and Weissella hellenica) were significantly correlated with the major volatile compounds, such as 2,3-butanediol, ethanol, 3-hydroxy-2-butanone, ethyl hexanoate and ethyl lactate. The results may provide a theoretical basis for improving the flavour and overall quality of dry sausage.

Optimisation of Urine Sample Preparation for Headspace-Solid Phase Microextraction Gas Chromatography-Mass Spectrometry: Altering Sample pH, Sulphuric Acid Concentration and Phase Ratio.

Headspace-solid phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS) can be used to measure volatile organic compounds (VOCs) in human urine. However, there is no widely adopted standardised protocol for the preparation of urine samples for analysis resulting in an inability to compare studies reliably between laboratories. This paper investigated the effect of altering urine sample pH, volume, and vial size for optimising detection of VOCs when using HS-SPME-GC-MS. This is the first, direct comparison of H2SO4, HCl, and NaOH as treatment techniques prior to HS-SPME-GC-MS analysis. Altering urine sample pH indicates that H2SO4 is more effective at optimising detection of VOCs than HCl or NaOH. H2SO4 resulted in a significantly larger mean number of VOCs being identified per sample (on average, 33.5 VOCs to 24.3 in HCl or 12.2 in NaOH treated urine) and more unique VOCs, produced a more diverse range of classes of VOCs, and led to less HS-SPME-GC-MS degradation. We propose that adding 0.2 mL of 2.5 M H2SO4 to 1 mL of urine within a 10 mL headspace vial is the optimal sample preparation prior to HS-SPME-GC-MS analysis. We hope the use of our optimised method for urinary HS-SPME-GC-MS analysis will enhance our understanding of human disease and bolster metabolic biomarker identification.

Application of Multivariate Data Analysis to the Determination of Multiclass Pesticide Residues in Fruits and Vegetables using Headspace Solid-Phase Microextraction Gas Chromatography-Mass Spectrometry

Design of experiment (DOE) was employed to develop a headspace solid phase microextraction gas chromatography-mass spectrometry (HS-SPME/GC-MS) method for multiresidue analysis. The significance of SPME parameters was determined using Placket-Burman (P-B) design. The main effect and the interaction effect of the significant factors were also determined followed by the optimization of the significant factors using central composite design (CCD). A Minitab® statistical software was used to generate both the 27-4 Placket-Burman and the central composite design matrix. The same statistical software was also employed in the determination of the optimum level of the significant parameters using surface response optimizer and desirability surface plot. The most significant factors are: extraction temperature (90%), extraction time (80%), the pH and stirring rate (50% and 60% respectively). The optimum parameters are: Temperature, 62 °C; time, 34 min; NaCl, 10%; stirring, 350rpm; pH, 6. The figures of merit of analytical methodologies was determined using an internal standard calibration method. The linearity of the developed method ranges from 1- 500 µg/kg and correlation coefficient (R2) greater than 0.99. The average recovery was found between 74 – 115% and relative standard deviation ranges from 1.1 – 14%. The developed method was used to analyze 14 multiclass pesticide residues in two fruit (pear and grape) and two vegetable (lettuce and broccoli) samples, and the method was found to be satisfactory with LOD between 0.17 – 7.34 µg/kg and LOQ ranges from 0.55 – 24.50 µg/kg. Keyword: Design of experiment (DOE), solid phase microextraction, response surface optimizer, pesticide residues, Central composite Design

Screening of volatile decay markers of minced pork by headspace-solid phase microextraction–gas chromatography–mass spectrometry and chemometrics

Headspace solid-phase microextraction coupled with gas chromatography–mass spectrometry (HS-SPME–GC–MS) was used to analyze the volatile compounds of minced pork meat during storage. The origin of aromatic hydrocarbons in pork was verified by migration test. Principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) were applied to characterize the profile of volatile compounds in pork meat and identify the potential volatile markers associated with the spoilage of pork. A total of 41 compounds were identified. Migration test showed that the aromatic hydrocarbons in raw pork are from packaging. Three compounds: ethanol, 2,3-butanediol and 2-ethyl-1-hexanol were selected based on the loading plot and their variables importance in the projection (VIP) values, since they contribute mainly to the discrimination of pork with different storage times. These compounds can be used as additional indicators for quality control of pork.

Non-target Screening Analysis of Volatile Organic Compounds in Drinking Water by Headspace-solid Phase Microextraction Gas Chromatography-Mass Spectrometry

Abstract A non-target screening analytical method for volatile organic compounds (VOCs) in drinking water by headspace-solid phase microextraction (HS-SPME) gas chromatography-mass spectrometry (GC-MS) was established. The operating parameters of HS-SPME were optimized by the peak number and area of extract. The optimal working conditions of four different extraction fibers (100 μm PDMS, 65 μm PDMS/DVB, 85 μm PA and 75 μm CAR/PDMS) were investigated, including incubation time, extraction time, extraction temperature, NaCl concentration and desorption time. The oil-water partition coefficient and the number of the substances extracted by the four fibers were compared, and the results showed that the substances extracted by 100 μm PDMS was the least, and these compounds also could be extracted by the other three fibers, so the 100 μm PDMS could be replaced by the other fibers. The three optimized fibers were used for the non-target screening of two tap water samples in Wuhan (the source water came from the Yangtze river and the Han river, respectively), and the substances with more than 70% match degree from NIST library were selected for analysis. The results showed that 35 substances identified in the tap water sample from the Han River, 34 substances in the tap water from the Yangtze River, and there were 18 found in common. Comparing the types of substances screened in the two water samples, it was found that the esters were the most abundant substances, followed by the aldehydes and phenols. No organic solvents were used in this method, which was environmentally friendly, and it could be used to screen and analyze the VOCs in tap water.

Profiling Patterns of Volatile Organic Compounds in Intact, Senescent, and Litter Red Pine (Pinus densiflora Sieb. et Zucc.) Needles in Winter

This study was aimed to investigate the changes of chemical composition of the volatile organic compounds (VOCs) emitted from red pine needles in the process of needle abscission or senescence. The VOCs in intact, senescent, and litter red pine needle samples were analyzed by headspace-solid phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC/MS). And then, multivariate statistical interpretation of the processed data sets was conducted to investigate similarities and dissimilarities of the needle samples. Principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) were used to investigate the dataset structure and discrimination between samples, respectively. From the data preview, the levels of major components of VOCs from needles were not significantly different between needle samples. By PCA investigation, the data reduction according to classification based on the chlorophyll a / chlorophyll b (Ca/Cb) ratio were found to be ideal for differentiating intact, senescent, and litter needles. The following OPLS-DA taking Ca/Cb ratio as y-variables showed that needle samples were well grouped on score plot and had the significant discriminant compounds, respectively. Several compounds had significantly correlated with Ca/Cb ratio in a bivariate correlation analysis. Notably, the litter needles had a higher content of oxidized compounds than the intact needles. In summary, we found that chemical compositions of VOCs between intact, senescent, and litter needles are different each other and several compounds reflect characteristic of needle.

Saccharomyces bayanus Enhances Volatile Profile of Apple Brandies

Qualitative and quantitative profiles of volatiles in alcoholic beverages depend mainly on the quality of raw materials, yeasts used for fermentation, and processing technique. Saccharomyces bayanus is a yeast species which is not commonly used for the production of alcoholic beverages, but it is able to produce volatiles that add desirable aroma. Since there is little information regarding the application of that microorganism for the production of apple brandies and how it affects volatile profile of finished products, we decided to address that issue. The aim of the study was to determine the impact of S. bayanus on the profile of volatile compounds and sensory properties of apple spirits obtained from three apple cultivars (Topaz, Rubin, and Elise) in comparison to spirits obtained from fermentation carried out spontaneously or with Saccharomyces cerevisiae. Obtained brandies were analysed using gas chromatography–flame ionization detector (GC–FID), solid phase microextraction–gas chromatography–mass spectrometry (SPME–GC–MS) and sensorially. In our study, brandies produced from musts fermented by S. bayanus demonstrated the highest concentration of ethyl esters and increased concentrations of isoamyl acetate, 2-phenylethyl acetate, ethyl palmitate and hexanol. Moreover, our results support the hypothesis that non-Saccharomyces yeasts which are present during spontaneous fermentation and demonstrate higher β-glucosidase activities enhance aroma of alcoholic beverages through releasing aroma compounds from glycosidic forms, e.g., α-phellandrene, (E)-β-fanesene, (Z,E)-α-farnesene, α-farnesene, and farnesol. Considering results obtained in sensory analysis, we proved that S. bayanus is suitable for the production of apple brandies, improving their flavour. Brandies obtained from musts fermented by S. bayanus obtained the highest average range for “overall note” parameter in sensory analysis.

Monitoring Cider Aroma Development throughout the Fermentation Process by Headspace Solid Phase Microextraction (HS-SPME) Gas Chromatography–Mass Spectrometry (GC-MS) Analysis

Volatile organic compounds (VOCs) play a crucial role in cider quality. Many variables involved in the fermentation process contribute to cider fragrance, but their relative impact on the finished odor remains ambiguous, because there is little consensus on the most efficient method for cider volatile analysis. Herein, we have optimized and applied a headspace solid phase microextraction gas chromatography–mass spectrometry (HS-SPME GC-MS) method for the chemical analysis of cider VOCs. We determined that the 30 min exposure of a divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) solid phase microextraction (SPME) fiber at 40 °C yielded detection of the widest variety of VOCs at an extraction efficiency &gt;49% higher than comparable fibers. As a proof-of-concept experiment, we utilized this method to profile cider aroma development throughout the fermentation process for the first time. The results yielded a very practical outcome for cider makers: a pre-screening method for determining cider quality through the detection of off-flavors early in the fermentation process. The aroma profile was found to be well established 72 h after fermentation commenced, with major esters varying by 18.6% ± 4.1% thereafter and higher alcohols varying by just 12.3% ± 2.6%. Lastly, we analyzed four mature ciders that were identically prepared, save for the yeast strain. Twenty-seven key VOCs were identified, off-flavors (4-ethylphenol and 4-ethyl-2-methoxyphenol) were detected, and odorants were quantified at desirable concentrations when compared to perception thresholds. VOCs varied considerably following fermentation with four novel strains of S. cerevisiae, evidencing the central importance of yeast strain to the finished cider aroma.

Detection of l-Methamphetamine and l-Amphetamine as Selegiline Metabolites.

Selegiline (SE) is a selective, irreversible monoamine oxidase-B inhibitor, used for reducing symptoms in early-stage Parkinson's disease. The metabolites of SE include l-methamphetamine, l-amphetamine and desmethylselegiline (DSE). The stereoisomers of SE metabolites, d-methamphetamine and d-amphetamine are highly addictive psychostimulants and some of the most abused drugs in South Korea. In order to differentiate medical SE users form illicit methamphetamine abusers, it is important to distinguish between the l-isomers and d-isomers in urine samples. A 52-year-old male, seemingly under the influence of intoxication and demonstrating abnormal behavior, was reported to the police. The initial urine test using a methamphetamine detection kit demonstrated a positive result. Given the initial results, the police officer requested a further analysis of the urine sample. The urine sample was screened using headspace-solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS). Both methamphetamine and amphetamine were detected, in addition to SE and DSE. To quantitate methamphetamine and amphetamine by HS-SPME-GC-MS, we performed a standard addition method due to the matrix effect of the case sample. Consistent with previous studies, our results indicated that the ratio of amphetamine to methamphetamine was 0.27, which was in the range of SE ingestion. Furthermore, we confirmed l-methamphetamine and l-amphetamine by chiral derivatization using (R)-(-)-α-methoxy-α-(trifluoromethyl) phenylacetyl chloride.

Effect of Pit Mud on Bacterial Community and Aroma Components in Yellow Water and Their Changes during the Fermentation of Chinese Strong-Flavor Liquor.

As the main by-product of Chinese strong-flavor liquor, yellow water plays an important role in the formation of flavor components. Yellow water from different fermentation periods (30th day, 45th day, 60th day) was selected to analyze the aroma components by Headspace solid phase micro-extraction Gas Chromatography–Mass Spectrometry, and the microorganism community was evaluated by high-throughput sequencing technology and bioinformatics analysis of DNA. As the fermentation time was prolonged, the main flavor components significantly increased, and the amount of the common microbial population between yellow water and pit mud increased gradually. Among the common microorganisms, Lactobacillus accounted for the largest proportion, at about 56.96%. The microbes in the yellow water mainly belonged to Firmicutes. The abundance of Bacilli (the main bacteria) gradually decreased with time, at 87.60% at the 30th day down to 68.87% at the 60th day, but Clostridia gradually increased from 10.29% to 27.48%. At the genus level, some microbes increased significantly from the 30th day to 60th day, such as Caproiciproducens, which increased from 2.65% to 6.30%, and Sedimentibacter, increasing from 0.47% to 2.49%. RDA analysis indicated that the main aroma components were positively correlated with Clostridia and negatively correlated with Bacilli.

Exploring ovarian cancer screening using a combined sensor approach: A pilot study

All cells release low molecular weight organic compounds that possess finite vapor pressures at body and/or ambient temperatures. These volatile organic compounds (VOCs) may possess an odor and can be found emanating from all body fluids. As cells turn malignant, analysis of changes in these VOCs can provide insight into cancer onset and diagnosis. Previous studies have demonstrated that dogs can be trained to distinguish ovarian cancer tissues of various stages and grades from normal ovarian tissue and other gynecological malignancies with sensitivity and specificity over 95%. When trained on biopsied tissue, dogs were able to detect the VOC disturbances in peripheral blood samples with the same accuracy. Building on these earlier studies, we examined the VOCs emanating from plasma samples from primary ovarian cancer patients, patients with benign reproductive tract growths, and healthy controls. We used a three-pronged sensor approach to analyze the VOCs from plasma: canines trained on tissue and plasma samples, analysis using solid phase microextraction gas chromatography–mass spectrometry, and novel single stranded DNA-coated carbon nanotube sensor field effect transistors. Each of the three experimental approaches used in this study provided preliminary evidence that plasma from ovarian cancer patients emits a volatile odor signature that can be distinguished from the VOCs of patients with benign ovarian tumors and controls. Our results provide optimism that a diagnostic approach based on the analysis of the VOC odor signature of ovarian cancer is achievable.