GC System Research Articles

Custom GC×GC configuration for the selective isolation or removal of compounds from complex samples.

We developed a novel approach to selectively isolate or remove nearly any compound from complex mixtures of volatile organic compounds. This was achieved by customizing a GC×GC system with a Deans switch, a passive splitter, and a custom-made adapter for sample recollection. The new setup was evaluated with 106 standard chemicals covering a wide range of volatility (boiling points: 56 - 343 ⁰C) and polarity (log P: 0.2 - 9.4). The method was used to remove two notorious malodorous compounds from spoiled wine samples. We found that the recovery can be maximized if a custom-made adapter is attached directly on the flame ionization detector port (average recovery rate of 76 ± 7 % for the standards). Eventually, we could selectively isolate or remove chemicals with peaks separated by a minimum distance of 50 ms for the second column throughout the whole chromatographic run. The developed system is expected to mainly be used in the field of flavor and fragrance analysis (i.e., selection of flavors and odorants of interest or removal of off-flavor or malodorous compounds). At present, we can reasonably collect about 100 ng of each single compound and are currently working on sample enrichment to improve our method to isolate sufficient amounts for further chemical analysis (e.g. high sensitivity nuclear magnetic resonance or chemical ionization tandem mass spectrometry).

Development of a Standardized Protocol for the Classification of Column Sets in Comprehensive Two-Dimensional Gas Chromatography

One-dimensional gas chromatography (1D-GC) stationary phases are generally classified according to their relative polarity into non-polar, semi-polar, and polar columns. In comprehensive two-dimensional gas chromatography (GC×GC), it is the polarity difference between the two tandem-assembled stationary phases that determines the selectivity of the column ensemble. This polarity difference is called orthogonality, and GC×GC column sets can be broadly categorized into four groups based on the direction of the serial coupling between the primary and secondary columns. A significant portion of the GC×GC column sets in use today are operated in forward-orthogonality mode, which means that the secondary column is more polar than the primary column. A growing number of reported GC×GC applications operate in reversed-orthogonality configurations, where the secondary column is less polar than the primary column. Very few examples exist of non-orthogonal column sets because of the fact that there is limited additional selectivity that the secondary column can offer over the separation that has already been achieved in the primary column when the two phases are either identical or close in polarity. The fourth group of GC×GC column sets, called hybrid orthogonality, involves the coupling of stationary phases with peculiar selectivity differences that manifest themselves in the bi-dimensional separation plots. In this work, we are presenting a normalized approach to GC×GC column set characterization that is based on the use of a reference mixture of standards called the Century Mix. The Century Mix contains 100 chemical probes of different functionalities that span a reasonable range of volatilities and polarities to capture the selectivity profile of any GC×GC column set. The Century Mix also contains important chemical probes that are used for 1D-GC column characterization (such as the Grob mix and the Rohrschneider/McReynolds compounds) to make some connections between the 1D-GC building block columns and the GC×GC column sets. We finally also outline some other important metrics of comparison that should be taken into consideration to assess the overall performance of a GC×GC system.

Performance Evaluation of an EI&CI Dual Ionization TOFMS Hyphenated with a Flow Modulated GC×GC System.

The use and compatibility of a dual-ionization TOFMS operating an EI source and a CI source in parallel using a single TOF mass analyzer with flow modulated two-dimensional GC (GC×GC) is described. Important figures of merit of the mass spectrometer that are required for two-dimensional GC hyphenation such as acquisition speed, ion source response, EI/CI switching, the GC transfer, and data alignment are carefully investigated and addressed. Improved fast switching ion optics allow switching in a 100 Hz frequency between EI and CI spectra sampled from the same GC×GC effluent. The spectra quality also influenced by the preseparation, especially of the EI source, is compared to a standard setup operating a single quadrupole MS coupled to the same GC system. Further, two setups including and excluding an additional flame ionization detector are presented. High increments in CI sensitivities are achieved by utilizing the high pumping efficiencies of the CI stage of the used mass spectrometer. By leading high flow ratios of the GC×GC modulation flows toward the CI source, the intensity can be increased by factors of up to 37 while maintaining the pressure balance of the less robust EI source. Finally, thermal desorption GC×GC-EI&CI-TOFMS analyses of traffic emission samples from a federal highway in Germany are executed with the presented setup.

Boosting the odour perception of trace compounds exploiting three-dimensional GC-O with MS/FID simultaneous detection

ABSTRACT The study describes the effectiveness of a 3D GC system coupled with olfactometric detection and simultaneous MS and FID (3DGC-O-MS/FID) to improve the detection of odorants. Mega-bore columns were used to ensure a sample capacity able to enhance the odour perception. The heart-cut approach allowed to overcome the low efficiency of wide-bore columns, granting to purify enriched target fractions before olfactometry detection. After the third GC dimension, the isolated target peaks were eluted to the olfactometric port allowing the odour to last multiple seconds, making the panelist’s perception easier and more comfortable. The simultaneous FID/MS detection after the third GC dimension allowed to match specific odours to target molecules and their concentration in the sample. The 3DGC-O-MS/FID system boosts odour perception of trace components compared to conventional GC-O approaches. A reduced detection threshold of mg/kg levels was obtained compared to the mg/kg levels typical of monodimensional GC-O.

Comparative studies of essential oils from Matricaria recutita L.

The aim of the work is to determine the component composition of the essential oil of medicinal chamomile, grown on the educational and research site of medicinal plants of Zaporizhzhia State Medical and Pharmaceutical University (ZSMPHU), and commercial essential oil that was purchased via the Internet. Materials and methods. The object of the study was chamomile essential oil obtained by hydrodistillation and commercial oil. Qualitative and quantitative determination of the components of essential oils was established using the chromato-mass spectrometric method on a high-performance gas chromatograph “Agilent 7890B GC System” (Agilent, SantaClara, CA, USA) with a mass spectrometric detector “Agilent 5977 BGC/MSD” (Agilent, SantaClara, CA, USA). Results. Dominant compounds of essential oil of chamomile, grown on the educational and research site of medicinal plants ZSMPHU were 2H-pyran-3-ol, tetrahydro-2,2,6-trimethyl-6-(4-methyl-3-cyclohexen-1-yl) ) – 7.54 %, chamazulene – 5.32 %, alpha-bisabolol – 4.30 %, 1H-cycloprop[e]azulen-7-ol, decahydro-3,1,7-trimethyl-4-methylene – 3.25 %, myrtenyl acetate – 3.03 %, azulene, 1,2,3,3a,4,5,6,7-octahydro-1,4-dimethyl-7-(1-methylethenyl) – 2.16 %, bisabolol oxide B – 1.86 %. Commercial chamomile essential oil was dominated by 3-methoxy-3-methylbutanol (56.15 %), diethyl phthalate (17.46 %), linalyl acetate (6.99 %), linalool (4.41 %). Conclusions. Industrial cultivation of chamomile in southern Ukraine shows a high biologically active substances content and can be in demand in the pharmaceutical industry’s consumer market for raw materials.

Gametocidal genes: from a discovery to the application in wheat breeding.

Some species of the genus Aegilops, a wild relative of wheat, carry chromosomes that after introducing to wheat exhibit preferential transmission to progeny. Their selective retention is a result of the abortion of gametes lacking them due to induced chromosomal aberrations. These chromosomes are termed Gametocidal (Gc) and, based on their effects, they are categorized into three types: mild, intense or severe, and very strong. Gc elements within the same homoeologous chromosome groups of Aegilops (II, III, or IV) demonstrate similar Gc action. This review explores the intriguing dynamics of Gc chromosomes and encompasses comprehensive insights into their source species, behavioral aspects, mode of action, interactions, suppressions, and practical applications of the Gc system in wheat breeding. By delving into these areas, this work aims to contribute to the development of novel plant genetic resources for wheat breeding. The insights provided herein shed light on the utilization of Gc chromosomes to produce chromosomal rearrangements in wheat and its wild relatives, thereby facilitating the generation of chromosome deletions, translocations, and telosomic lines. The Gc approach has significantly advanced various aspects of wheat genetics, including the introgression of novel genes and alleles, molecular markers and gene mapping, and the exploration of homoeologous relationships within Triticeae species. The mystery lies in why gametes possessing Gc genes maintain their normality while those lacking Gc genes suffer abnormalities, highlighting an unresolved research gap necessitating deeper investigation.

Flow-modulation comprehensive two-dimensional enantio-gas chromatography: A valid and flexible alternative to heart-cutting multidimensional enantio-gas chromatography

The present research is focused on the proposal of use of flow-modulation comprehensive two-dimensional enantio-gas chromatography (FM eGC × GC) as a valid, flexible, and possibly superior alternative to heart-cutting multidimensional enantio-GC (eMDGC). The latter, a technique of demonstrated utility, is used specifically for the targeted separation of chiral compounds, whereas FM eGC × GC can produce both targeted and high-resolution untargeted information in a single run. It is clearly possible to use eMDGC for untargeted analysis, often with a flame ionization detector (stand-by analysis), to monitor a first-dimension (1D) separation, of much lower peak capacity compared to FM eGC × GC. If eMDGC is used with mass spectrometry (MS), it is normally exploited to monitor the second-dimension (2D) separation.The analytical instrument consisted of automated solid-phase microextraction (SPME), and a low duty-cycle FM eGC × GC system (with time-of-flight MS), equipped with an enantioselective 1D column (2,3-di-O-methyl-6-t-butyl silyl β-cyclodextrin derivative) and a 2D polyethylene glycol one. Ten Marsala wines were subjected to analysis, for the determination of chiral lactones (many at the low ppb level, due to the high concentration capacity of SPME) and for general analyte profiling. In many instances, highly complex chromatograms were attained, with statistical analysis (ANOVA-simultaneous component analysis and partial least squares discriminant analysis) used for sample differentiation.

Compatibility of cloud point extraction with gas chromatography: Matrix effects of Triton X-100 on GC-MS and GC-MS/MS analysis of organochlorine and organophosphorus pesticides

Cloud point extraction is an environmentally benign and simple separation/concentration procedure that can be regarded as an alternative to classical liquid-liquid extraction. In the current work, it was studied the compatibility of cloud point extraction followed by back-extraction in low volume of organic solvent with gas chromatography-mass spectrometry (GC-MS and GC-MS/MS). Triton X-100 was preferred than Triton X-114 as a surfactant to produce the clouding phenomenon and hexane or isooctane was found to be appropriate organic solvents which can be used at the back-extraction step. It was observed that ca. 0.09 % w/w Triton X-100 was co-extracted in the organic phase (hexane or isooctane) so further study was carried out to find out its effect on the GC-MS (GC-MS/MS) measurement when liquid samples are injected without any pre-cleaning to remove the surfactant. The chromatographic separation and the mass detection were not deteriorated by the concomitant Triton X-100 for analysis of several Organochlorine and Organophosphorus pesticides (alpha-HCH, beta-HCH, gamma-HCH, Pentachlorobenzene, Hexachlorobenzene, Chlorpyrifos, Chlorpyrifos-methyl, Aldrin, Endrin, Dieldrin, alpha-Endosulfan, Heptachlor, Heptachlor-endo-epoxide-A, o,p-DDD, p,p-DDD, o,p-DDE, p,p-DDE, o,p-DDT and p,p-DDT). The stability of the GC system when introducing surfactant was assessed as acceptable (typically the peak area RSD% for 20 consecutive injections were below 5 %). Under the developed vaporization conditions using PTV or PSS injectors it can be deduced that Triton X-100 is deposited on the inner surface of the liner. This effect is beneficial since the resulting surfactant layer makes a surface which facilitates the pesticides transfer to the GC column. As a consequence, for some analytes, a substantial enhancement (up to 2.3 times) in the sensitivity was observed when the matrix-matched medium (0.09 % w/w Triton X-100 in organic solvent) is used compared to calibration in solely hexane or isooctane. Meanwhile, the measurement precision in the presence of Triton X-100 remains unchanged. The GC-MS/MS analysis was alternatively accomplished by the use of glass or metal liner and it was found that the glass one should be preferable. Finally, it can be concluded that cloud point extraction with Triton X-100 can be combined with GC-MS or GC-MS/MS analysis by applying liquid injection of the target analytes transferred in organic solvents such as hexane or isooctane. We have established a positive effect of Triton X-100 on the instrumental performance which is on opposite to the generally accepted concern of the negative influence of the surfactants on the gas chromatographic analysis.

A New Herbal Medicine Formulation with Potential Anti-scabies Properties to Treat Demodex and Sarcoptes Parasites.

Scabies is considered an external parasite notorious for its high prevalence causing severe and contagious skin lesions in humans and animals worldwide. This study has introduced a medicine to treat dogs infested with scabies (variants of Demodex, Sarcoptes, Psoroptes, Otodectes, etc.). The present study offers a no-side-effect herbal formulation to treat dogs infested with scabies. Unlike oral and injectable medicines, which take the form of an ointment and are topically applied on-site, this medicinal formulation can be easily used without concerns over its side effects or consumption dosages. This medicinal formulation requires no skin rinsing due to its herbal and high skin absorption properties, as recovery may take less than a month with a maximum of two times of application. To carry out the experiment, 25 sick dogs with various breeds and ages suspected of scabies were gathered. Following accurate morphological examinations of all the samples, a deep skin chip of the lesion site was provided, which was examined by a microscope. Then, 13 dogs (Mix, Terrier, Pug, Husky, Spitz) were infested with Demodex scabies and 12 dogs (Pittbull, Mix, Shih Tzu, Terrier, Boxer, Setter) with Sarcoptic scabies. The prepared product was topically administered at a constant 2% dosage to the bodies of all the samples. To prepare the ointment, 1 g of Borax (Na2B4O7·10H2O) was first dissolved in 35 g deionized water and heated to 70°C. Then, 45 g of liquid paraffin (CnH2n+2) was mixed with 1 g of Carvacrol (C10H14O) and 1 g of geranium (C10H18O) and stirred well to become a phase. Later, 17 g of the melted beeswax (C15H31COOC30H61) was added to the liquid paraffin compound. In the end, the aqueous phase was added to the oil phase, and the mixture process immediately began in one direction with a glass stirrer and continued until the product cooled down. Essential oils (EO) was obtained by steam distillation of fresh Thyme and Rose-Acented Geranium in a stainless steel distillation apparatus (alembic) for 3 h. The main components of the essential oils used in the formulation were performed using a Hewlett-Packard GC system interfaced with a mass spectrometer equipped with an HP5-MS capillary column (30 m, 0.32 mm, 0.25 µm film thicknesses). For GC-MS detection, electron ionization with ionization energy of 70 eV was used. To examine the presence of scabies, weekly skin sampling was performed, and the treatment continued until 30 days, when no skin chip of the scabies was noted. The findings revealed that the formulation developed no side effects and removed the daily use, as it could be administered once or twice a week. Also, complete recovery of scabies in all the breeds was found to be less than a month at most. This medicinal formulationcan be easily used without concerns over its side effects or consumption dosages. This study introduced a herbal formulation with effective herbal ingredients without any side effects to treat the sarcoptes and demodex parasites; unlike other chemical compounds, this medicinal formulation has no side effects, while some other formulations could develop side effects.

Characterization of polycyclic aromatic hydrocarbons (PAHs) in atmospheric particles (PM2.5) in the North China Plain using positive-ion atmospheric pressure photoionization (APPI) coupled with fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS)

Many aromatic compounds, including 16 types of U.S. EPA priority PAHs, exist in substituted or unsubstituted forms and have high toxicities. Aromatic compounds in aerosols collected in the North China Plain (NCP) were characterized by GC-MS and atmospheric pressure photoionization (APPI) Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR MS). The concentrations of the 16 types of PAHs in the collected samples ranged from 277.0 to 876.8 ng/m3, which were higher than those collected in other regions and countries. Previous studies reported that only 27 wt% of aromatic compounds could be eluted using the GC system and demonstrated that APPI FT-ICR MS is a useful method for identifying large-molecular aromatics. In this study, two samples collected from the NCP were successfully characterized by APPI FT-ICR MS. In the APPI + mode, 231 and 228 CH formulas (containing only C and H and having a double bond equivalent (DBE) of 4 or greater) were identified, accounting for 10% of the numerical fraction and more than 40% of the intensity fraction. The FT-ICR data revealed that condensed PAHs with 6–8 aromatic rings had relatively high abundances and that a series of PAH homologs (alkylated PAHs) with identical DBE values ranging from 4 to 30 were present. Furthermore, heteroatom groups were also identified as significant components of the aromatic fractions. The O1, O2, N1, NO2, and S1 class species with DBE values of 3–34 and carbon numbers of 11–42 were identified by APPI FT-ICR MS. The heteroatom PAHs had DBE values and carbon number distributions similar to regular PAHs. The aromatic fractions determined in this work provide useful data for future quantitative analyses of aromatic compounds with high toxicities and our findings will help improve the current understanding of PAH compositions in the northern China. However, further research is needed to determine the abundances and toxicities of various apparent or substituted PAHs outside of the 16 types identified by the U.S. EPA as priority PAH compounds, which have been extensively researched.

Targeted Analyte Deconvolution and Detection of Piper longum Leaf Volatiles Using Two-Dimensional Gas Chromatography and Time-of-Flight Mass Spectrometry

Piper longum L., known as long pepper, is an important species of the family Piperaceae due to its commercial and medicinal properties. However, its volatiles have only been analyzed by gas chromatography–mass spectrometry (GC–MS). The present study focused upon the precise characterization of Piper longum L. leaf volatiles for the first time by two-dimensional gas chromatography–time-of-flight mass spectrometry (GC × GC–TOF-MS). A total of 104 constituents accounting for 91.79% of the essential oil were identified due to the enhanced chromatographic separation and mass spectral deconvolution of GC × GC–TOF-MS, of which 20 constituents were reported first time. The identified constituents were categorized into alkanes (4.07%), alkenes (0.12%), aldehydes (0.52%), alcohols (6.87%), esters (2.40%), ether (0.26%), ketones (3.78%), monoterpene hydrocarbons (15.48%), oxygenated monoterpenes (4.21%), sesquiterpene hydrocarbons (22.68%), oxygenated sesquiterpenes (30.4%), diterpenes (0.75%), phenylpropanoids (0.14%), and fatty acids (0.15%). Among the classes, oxygenated sesquiterpenes were found to be the major group with E-nerolidol as the dominant compound (18.92 ± 0.02%), followed by β-pinene (5.41 ± 0.02%), α-pinene (4.44 ± 0.02%), and Z-caryophyllene (3.14 ± 0.03%). Additionally, GC × GC–TOF-MS separated 24 coeluting constituents which were unresolved using the one-dimensional GC column, hence justifying to be a noteworthy approach for analysing volatiles by two-dimensional GC system. The in-depth terpenic characterization may influence the overall quality of the oil as well as allow the future improvement of the species.

Gas Chromatography-Mass Spectroscopy(GC-MS) of Chloroform Extract of Ficus exasperata Vahl

Gas Chromatography-Mass Spectrometry (GCMS) analysis of chloroform leaves extract of Ficus exasperate Vahl was performed to identify the composition and percentage abundance of the various phytochemical constituents of Ficus exasperate Vahl. The extract was obtained by fractionating methanol crude leave extract of Ficus exasperate Vahl with in order of increasing polarity, n-Hexane then chloroform. GC-MS analysis was carried out on a GC system comprising a Gas Chromatograph interfaced to a Mass Spectrometer (GC-MS) instrument. The components were compared with the database of spectrum of known components stored in the gas chromatography-mass spectrometry library. Gas Chromatography-Mass Spectrometry analysis of the chloroform leave extract of Ficus exasperate revealed the presence of acyclic olefin which is used for tanning oils and in synthetic fatty acids, Isopryl myristate used in cosmetics, Dibutyl phthalate which is used in cosmetics, textile, safety glass additive, oleic acid used in pharmaceuticals, Cyclopropanecarboxylic acid, 3-(2,2-dichlor used in agrochemicals and pharmaceuticals. The presence of these compounds justifies the use of some parts of the plant for various elements in folklore and can be advised as a plant of phytopharmaceutical and industrial importance.

Bioactive components in ethanol extract of Citrullus lanatus rind using Gas Chromatography- Mass Spectroscopy.

The knowledge of bioactive compounds present in a plant can be helpful in utilizing it for a medicinal purpose in life. The Gas Chromatography-Mass Spectrometry (GCMS) analysis of ethanol extract of Citrullus lanatus rind (CLR) was done to identify bioactive compounds and selectivity or abundance percentage in ethanol extract of CLR. The extract was obtained by fractionating crude ethanol CLR extract in order of increasing polarity, n-Hexane, chloroform, ethylacetate and ethanol. The GC-MS analysis was carried out on GC system comprising Gas Chromatograph interfaced to Mass Spectrometer (GC-MS) instrument. The bioactive compounds obtained were compared with database of spectrum of known components stored in the gas chromatography-mass spectrometry library. The GC-MS analysis of ethanol extract of CLR revealed the presence of androst-4-en-9-thiocyanomethyl-11-ol-3,17-dione a steroid which is a precusor for androgen and estrogen production. As well as cyclooctasiloxane hexadecamethyl and octasiloxane hexadecamethyl in which both of them contain silicon an essential trace element for collagen and bone formation .The presence of these compounds validates the use of ethanol extract of CLR as a good antioxidants, antibacterial agents and stimulant in precursor of male reproductive hormone production. The ethanol extract of CLR can be of great value in ethno-veterinary practice.

Chemical Composition of Volatile Organic Compounds of an Extremely Rare and Endemic Algerian Apiaceae Species, Bunium crassifolium Batt.

Abstract Bunium crassifolium Batt. (B. crassifolium) (Apiaceae) is an extremely rare endemic species from the North East of Algeria. In this study, we extracted the volatile organic compounds (VOC) of B. crassifolium Batt. aerial parts using an Agilent G1888 network headspace sampler coupled with an Agilent 7890 GC system. The results revealed the presence of twenty-two (22) compounds, twenty (20) of which were identified as representing 97.48% of the total composition, the major components are: 44.67% of β-Cubebene, 8.82% of β-Caryophyllene, 7.04% of γ-Elemene, 4.70% of δ-Cadinene, 4.11% of γ-Cadinene, 3.77% of Ascaridole and 3.33% of β-Elemene, along with other constituents at a relatively low amount.

Comparative Analysis of Quality of Essential Oil of Wormwood Herb Synanthropic Flora of Voronezh Region

Introduction. The formation and accumulation of biologically active substances in plants is a complex process associated with a number of environmental factors, including anthropogenic ones. The study of the characteristics of the qualitative composition of essential oil of wormwood grass of bitter different from the ecological point of view of the places of harvesting is relevant.Aim. The aim of this study study of the qualitative composition of essential oil of bitter wormwood grass, harvested in areas of the Voronezh region that are different from an ecological point of view.Materials and methods. In the Voronezh region, 4 points of raw materials procurement were selected, diverse in terms of anthropogenic impact. Isolation of essential oil from the raw materials was carried out according to the method of PS "Wormwood of bitter grass". Component composition of the obtained essential oils was determined using Agilent 7890B GC System (Agilent Technologies, USA) with Agilent 5977A MSD mass selective detector (Agilent Technologies, USA). Data analysis and processing was carried out on the basis of NIST11 databases (from 19.05.2011), MassHunter ver. B.06.00 and NIST MS Search ver. 2.0 software were used.Results and discussion. In a sample of essential oil obtained from reserved raw materials, monoterpene compounds account for more than 82 %, and sesquiterpene compounds – 16.6 %, about 2 % are organic impurities. Intensive biosynthesis of monoterpenes was noted in a sample collected in the area of agricultural fields of the Verkhnekhavsky district, its mass fraction is more than 73 %. In samples of raw materials with anthropogenic load (OJSC "Minudobreniya" and Highway M4), the share of monoterpene compounds is significantly lower (63.7 and 49 %, respectively). The increase in the proportion of sesquiterpene compounds in the last samples of wormwood essential oil may be due to the excessive acidity of the urbanized places of the workpiece. The sesquiterpene compound hamazulene, which stains essential oil blue, is identified in only two samples of gorse grass wormwood harvested along agricultural fields and in M4 tracks, which explains the presence of a blue hue in these oils.Conclusion. The chromato-mass spectrometric analysis of the essential oil of the studied samples of bitter wormwood grass made it possible to identify more than 70 different components in them, while the qualitative composition of the essential oil of the raw materials of different places of the workpiece was significantly different, which may indicate a significant influence of the place of growth of the species and anthropogenic factors on the features of the secondary metabolism of terpene compounds in the plant organism.

Second-Dimension Temperature Programming System for Comprehensive Two-Dimensional Gas Chromatography. Part 1: Precise Temperature Control Based on Column Electrical Resistance.

A second-dimension temperature programming system (2DTPS) for comprehensive two-dimensional gas chromatography (GC × GC) is introduced, and its performance is characterized. In the system, a commercial stainless-steel capillary column was used for the separation, as a heating element, and as a temperature sensor. The second dimension (2D) column was resistively heated and controlled using an Arduino Uno R3 microcontroller. Temperature measurement was accomplished by measuring the overall 2D column's electrical resistance. A diesel sample was used to compare the 2D peak capacity (2nc) and resolution (2Rs), while a perfume sample was used to compare the reproducibility of the system for within-day (n = 5) and day-to-day (n = 5) results. The 2nc improved by 52% with the 2DTPS compared to the secondary oven. The GC × GC system utilizing the 2DTPS had an average within-day and day-to-day relative standard deviation (RSD) of 0.02 and 0.12% for the 1D retention time (1tR), 0.56 and 0.58% for the 2D retention time (2tR), and 1.18 and 1.53% for the peak area, respectively.

A New Herbal Medicine Formulation with Potential Anti-scabies Properties to Treat Demodex and Sarcoptes Parasites

Scabies is considered an external parasite notorious for its high prevalence causing severe and contagious skin lesions in humans and animals worldwide. This study has introduced a medicine to treat dogs infested with scabies (variants of Demodex, Sarcoptes, Psoroptes, Otodectes, etc.). The present study offers a no-side-effect herbal formulation to treat dogs infested with scabies. Unlike oral and injectable medicines, which take the form of an ointment and are topically applied on-site, this medicinal formulation can be easily used without concerns over its side effects or consumption dosages. This medicinal formulation requires no skin rinsing due to its herbal and high skin absorption properties, as recovery may take less than a month with a maximum of two times of application. To carry out the experiment, 25 sick dogs with various breeds and ages suspected of scabies were gathered. Following accurate morphological examinations of all the samples, a deep skin chip of the lesion site was provided, which was examined by a microscope. Then, 13 dogs (Mix, Terrier, Pug, Husky, Spitz) were infested with Demodex scabies and 12 dogs (Pittbull, Mix, Shih Tzu, Terrier, Boxer, Setter) with Sarcoptic scabies. The prepared product was topically administered at a constant 2% dosage to the bodies of all the samples. To prepare the ointment, 1 g of Borax (Na₂B₄O₇·10H₂O) was first dissolved in 35 g deionized water and heated to 70°C. Then, 45 g of liquid paraffin (CnH2n+2) was mixed with 1 g of Carvacrol (C10H14O) and 1 g of geranium (C10H18O) and stirred well to become a phase. Later, 17 g of the melted beeswax (C15H31COOC30H61) was added to the liquid paraffin compound. In the end, the aqueous phase was added to the oil phase, and the mixture process immediately began in one direction with a glass stirrer and continued until the product cooled down. Essential oils (EO) was obtained by steam distillation of fresh Thyme and Rose-Acented Geranium in a stainless steel distillation apparatus (alembic) for 3 h. The main components of the essential oils used in the formulation were performed using a Hewlett-Packard GC system interfaced with a mass spectrometer equipped with an HP5-MS capillary column (30 m, 0.32 mm, 0.25 µm film thicknesses). For GC–MS detection, electron ionization with ionization energy of 70 eV was used. To examine the presence of scabies, weekly skin sampling was performed, and the treatment continued until 30 days, when no skin chip of the scabies was noted. The findings revealed that the formulation developed no side effects and removed the daily use, as it could be administered once or twice a week. Also, complete recovery of scabies in all the breeds was found to be less than a month at most. This medicinal formulationcan be easily used without concerns over its side effects or consumption dosages. This study introduced a herbal formulation with effective herbal ingredients without any side effects to treat the sarcoptes and demodex parasites; unlike other chemical compounds, this medicinal formulation has no side effects, while some other formulations could develop side effects.

Comparing the Chemical Profiles of Plant-Based and Traditional Meats Using GC–MS-Based Metabolomics

As the consumer interest and market for plant-based meat alternatives grows, understanding the nutritional differences between alternative and traditional meats is essential. This article describes an untargeted gas chromatography–mass spectrometry (GC–MS)-based metabolomics approach that compares the chemical profiles of a popular plant-based meat alternative and grass-fed ground beef using a GC system coupled to a GC–MS device. The samples were derivatized to simplify the chromatographic process and render the polar metabolites more volatile for GC–MS analysis. Statistical and multivariate analysis of the acquired and processed GC–MS data revealed that 90% of the annotated compounds differed between the plant-based alternative meat and the grass-fed ground beef samples. The ground beef and plant-based products each contained several compounds that were found in much smaller quantities, or not at all, in the other product. These results indicate differences in organic composition even though the nutritional labels on the back of the products were nearly identical. Heat maps, principal component analysis (PCA) score plots, variable importance plots (VIPs), and the clustering of compounds into metabolite classes provided further insights into the differences between the two types of meat products. The biological significance of the comparative data was studied using online databases and pathway analysis tools.

Top-Down Approach to Retention Time Prediction in Comprehensive Two-Dimensional Gas Chromatography-Mass Spectrometry.

In this contribution, we describe a novel modeling approach to predicting retention times (tr) in comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC × GC-ToF-MS) with a particular emphasis on the second-dimension (2D) retention time predictions (2tr). This approach is referred to as a "top-down" approach in that it breaks down the complete GC × GC separation into two independent one-dimensional gas chromatography separations (1D-GC). In this regard, both dimensions, that is, first dimension (1D) and second dimension (2D) are treated separately, and the cryogenic modulator is simply considered as a second consecutive injection device. Separate 1D-GC tr predictions are performed on both dimensions using the same flow rate as the one deployed in the conventional GC × GC system. The separate tr predictions are then combined to account for the two-dimensional separation. This model was applied to 24 analytes from 2 standard mixtures (Grob Test Mix and Fragrance Materials Test Mix) and assessed across 9 GC × GC chromatographic conditions. The experimental and predicted chromatographic retention space occupations were assessed by using the convex hull approach defined by the Delaunay triangulation. The predicted percentage of space occupation corresponded favorably with the experimental values. Furthermore, the top-down approach enabled an accurate prediction of the 2tr of all investigated analytes, providing an average 2tr modeling error of 0.26 ± 0.01 s.

2-Dimensional Gas Chromatography-Mass Spectroscopy: A Review

Gas Chromatography separates components in time. Mass spectroscopy provides information that aids in the identification and structural elucidation of each component. Comprehensive 2-Dimensional gas chromatography (GC×GC) is a novel technique. The revolutionary aspect of GC x GC, with respect to classical multidimensional chromatography, is that the entire sample is subjected to two distinct analytical separations. The resulting enhanced separating capacity makes this approach a prime choice when GC analysts are challenged with highly complex mixtures. The combination of a third mass spectrometric dimension to a GC x GC system generates the most powerful analytical tool today for volatile and semi-volatile analytes. The present review is focused on the instrumentation of 2D GC-MS, the difference between GC and 2d GC, application of 2d GC-MS have been discussed.