Gas Chromatography-mass Spectrometry Instrument Research Articles

Metabolite profile of tree marigold (Tithonia diversifolia (Hamsley) A. Grey) leaves

Tree marigold or Tithonia diversifolia (Hemsley) A. Grey) also known as Insulin leaves has traditionally been used as an herb for the treatment of diabetes mellitus (DM). Tree marigolds contain various metabolite compounds, which have various bioactivities, so research was carried out to study metabolite profiles using a non-target metabolism approach using a GC-MS (Gas Chromatography-Mass Spectrometry) instrument. The results of GC-MS analysis of Tree marigold ethanol extract showed 30 peaks in the chromatogram, of which 7 were dominant metabolite compounds including 1-butanol, 3-methyl acetate (28.11%), Thunbergol (14.28%), Geranyl acetate (12.13%). ), D-Limonene (6.64%), 4H-Pyran-4-one, 2,3-Dihydro-3,5-dihydroxy-6 -methyl (5.05%), acetic acid (4.10%), 7.8-epoxy-α-ionone (2.91%). The various categories of metabolites consist of the monoterpene class followed by fatty acids, terpenes, and sesquiterpenoids, as well as other compounds in the terpenoid esters class, alkanoic acids, fatty acids, proteins, amino acids, furanoids, ketones, and others. These metabolite compounds have antidiabetic, antioxidant, anti-inflammatory, antimicrobial, antibacterial, anticancer, and antitumor effects so they have potential as antidiabetic therapy.

Tandem Mass Spectrometry across Platforms.

PubChem serves as a comprehensive repository, housing over 100 million unique chemical structures representing the breadth of our chemical knowledge across numerous fields including metabolism, pharmaceuticals, toxicology, cosmetics, agriculture, and many more. Rapid identification of these small molecules increasingly relies on electrospray ionization (ESI) paired with tandem mass spectrometry (MS/MS), particularly by comparison to genuine standard MS/MS data sets. Despite its widespread application, achieving consistency in MS/MS data across various analytical platforms remains an unaddressed concern. This study evaluated MS/MS data derived from one hundred molecular standards utilizing instruments from five manufacturers, inclusive of quadrupole time-of-flight (QTOF) and quadrupole orbitrap "exactive" (QE) mass spectrometers by Agilent (QTOF), Bruker (QTOF), SCIEX (QTOF), Waters (QTOF), and Thermo QE. We assessed fragment ion variations at multiple collisional energies (0, 10, 20, and 40 eV) using the cosine scoring algorithm for comparisons and the number of fragments observed. A parallel visual analysis of the MS/MS spectra across instruments was conducted, consistent with a standard procedure that is used to circumvent the still prevalent issue of mischaracterizations as shown for dimethyl sphingosine and C20 sphingosine. Our analysis revealed a notable consistency in MS/MS data and identifications, with fragment ions' m/z values exhibiting the highest concordance between instrument platforms at 20 eV, the other collisional energies (0, 10, and 40 eV) were significantly lower. While moving toward a standardized ESI MS/MS protocol is required for dependable molecular characterization, our results also underscore the continued importance of corroborating MS/MS data against standards to ensure accurate identifications. Our findings suggest that ESI MS/MS manufacturers, akin to the established norms for gas chromatography mass spectrometry instruments, should standardize the collision energy at 20 eV across different instrument platforms.

Aloe adigratana Reynolds: Preliminary Phytochemical Screening, Proximate Content, Essential Oil Analysis, and In Vitro Antifungal Activity Studies of Its Leaf Peels and Gel.

Aloe species are among the most significant plants with several applications. Many of the species, however, are underexplored, owing to their scarcity and limited geographical distribution. A. adigratana Reynolds, which is common in Ethiopia, is one of the little-studied and endangered Aloe species. This preliminary study focuses on the phytochemical screening, proximate analysis, essential oil content, and antifungal activities of A. adigratana leaf peels. Antifungal activities were also tested on the gels of the plant for comparison. Standard procedures were used for phytochemical and proximate composition studies. Essential oil analysis was performed using a gas chromatography-mass spectrometry instrument. Using the well-diffusion method, investigations on antifungal activity were performed on three clinically isolated specimens of dandruff-causing fungus; namely, Malassezia furfur, Malassezia restricta, and Malassezia globosa. The leaf peels of A. adigratana contained alkaloids, flavonoids, tannins, and terpenes. The mean moisture, ash, and crude fat levels were 85.69, 92.20, and 8.00%, respectively, whereas the mean total protein and mean total carbohydrate values were 2.59 and 3.04%. Gas chromatography-mass spectrometry investigation confirmed the presence of fifteen essential oils. The most prevalent essential oil component was discovered to be phytol (33.78%), followed by decane (11.29%). In a dose-dependent way, the leaf latex and gel extracts prevented the growth of three dandruff-causing Malassezia fungal species (M. furfur, M. restricta, and M. globosa). Both the latex and gel demonstrated the maximum activity on M. globosa, the most prevalent fungus in the research area, with minimum inhibitory concentrations of 0.24 and 0.48 mg/mL and minimum fungicidal concentrations of 0.48 and 0.97 mg/mL, respectively. In general, the proximate and essential oil compositions of A. adigratana leaves were comparable to those of other Aloe species widely used in the food, cosmetic, and pharmaceutical industries, implying that A. adigratana could be a potential future plant for such industries.

Geochemical evolution of kerogen type III during hydrous pyrolysis: A case study from the Damoguaihe Formation, Hailar Basin, China

In order to evaluate changes in geochemistry, organic petrology, and chemical composition of petroleum and byproducts, an immature sample from the Damoguaihe Formation in Hailar Basin in China was examined using hydrous pyrolysis (HP) at the following temperature steps: 300 °C, 325 °C, 350 °C, 365 °C, 400 °C, and 450 °C. The final product from each pyrolysis step was assessed with several analytical methods including programmed pyrolysis, Gas Chromatography (GC), Gas Chromatography-Mass Spectrometry (GC-MS) and organic petrology. Rock-Eval pyrolysis revealed that the geochemical parameters including TOC, S2, HI, and Tmax changed as thermal maturity advanced. Both un-extracted and extracted organic matter (OM) showed a steady decrease in TOC, HI, and OI as the temperature increased. On the other hand, a general increase in Tmax values with increasing temperature was observed. Regarding GC analysis, fluctuations were observed in n-alkanes during pyrolysis. In general, lower molecular weight n-alkanes of <C17 increased between 325 °C and 400 °C, and heavier n-alkanes fluctuated with increasing temperature. Similarly, GC-MS results showed variations in biomarkers with increasing pyrolysis temperature. These variations could stem from the GC-MS instrument's inability to detect light hydrocarbons, specifically at higher temperatures beyond the oil generation window into the gas window. Some biomarkers, including Ts/Tm, C29H/C30H, Gammacerane Index (GI), C23 tricyclic terpane/C24 tetracyclic terpane showed that the Damoguaihe Formation has a carbonate lithology and was deposited in a freshwater environment with no water stratification. Based on organic petrography, an increase in temperature caused optical and structural changes in the macerals. Organic petrography also showed that the Damoguaihe Formation contains different maceral groups such as liptinite, vitrinite, and inertinite, and hence a combination of kerogen types II, III, and IV. Based on these observations, a deltaic depositional setting is envisaged for the Damoguaihe Formation in the study area, which is also confirmed by previous studies.

Influence of pH and salts on DMF-DMA derivatization for future Space Applications

For gas chromatography - mass spectrometry (GC-MS) analyses performed in situ, pH and salts (e.g., chlorides, sulfates) may enhance or inhibit the detection of targeted molecules of interest for astrobiology (e.g. amino acids, fatty acids, nucleobases). Obviously, salts influence the ionic strength of the solutions, the pH value, and the salting effect. But the presence of salts may also produce complexes or mask ions in the sample (masking effect on hydroxide ion, ammonia, etc.). For future space missions, wet chemistry will be conducted before GC-MS analyses to detect the full organic content of a sample. The defined organic targets for space GC-MS instrument requirements are generally strongly polar or refractory organic compounds, such as amino acids playing a role in the protein production and metabolism regulations for life on Earth, nucleobases essential for DNA and RNA formation and mutation, and fatty acids that composed most of the eukaryote and prokaryote membranes on Earth and resist to environmental stress long enough to still be observed on Mars or ocean worlds in geological well-preserved records. The wet-chemistry chemical treatment consists of reacting an organic reagent with the sample to extract and volatilize polar or refractory organic molecules (i.e. dimethylformamide dimethyl acetal (DMF-DMA) in this study). DMF-DMA derivatizes functional groups with labile H in organics, without modifying their chiral conformation. The influence of pH and salt concentration of extraterrestrial materials on the DMF-DMA derivatization remains understudied. In this research, we studied the influence of different salts and pHs on the derivatization of organic molecules of astrobiological interest with DMF-DMA, such as amino acids, carboxylic acids, and nucleobases. Results show that salts and pH influence the derivatization yield, and that their effect depend on the nature of the organics and the salts studied. Second, monovalent salts lead to a higher or similar organic recovery compared to divalent salts regardless of pH below 8. However, a pH above 8 inhibits the DMF-DMA derivatization influencing the carboxylic acid function to become an anionic group without labile H. Overall, considering the negative effect of the salts on the detection of organic molecules, future space missions may have to consider a desalting step prior to derivatization and GC-MS analyses.

AUTHENTICATION OF RATTUS NORVEGICUS FAT AND OTHER ANIMAL FATS USING GAS CHROMATOGRAPHY-MASS SPECTROMETRY (GC-MS) AND PRINCIPAL COMPONENT ANALYSIS (PCA)

Objective: The objective of this study was to analyze fatty acids using Gas Chromatography-Mass Spectrometry (GC-MS) in combination with chemometric Principal Component Analysis (PCA) for the authentication of Rattus norvegicus fat from other animal fats.&#x0D; Methods: Extraction of fat from raw meat of Rattus norvegicus, beef, chicken, pork, and dogs using the Bligh Dyer method, then derivatized with 0.2 N NaOCH3, precipitation of sodium glycerol was carried out by adding saturated NaCl to obtain methyl esters which were then injected into the GC-MS instrument. The GC-MS data were then processed using chemometric Principal Component Analysis (PCA) to group Rattus norvegicus fat with other animal fats (beef, chicken, pork, and dog).&#x0D; Results: The results of the study revealed that fatty acids in Rattus norvegicus using GC-MS produced eleven types of fatty acids, namely: Lauric acid (1,1%), Myristic acid (1,15%), Palmitic acid (21,12%), Palmitoleic acid (2,06%), Stearic acid (8,23%), Vaccenic acid (2,43%), Oleic acid (26,51%), Linoleic acid (19,19%), Arachidic acid (0,09%), and Eucosatrienoic acid (0,39%). Chemometrics Principal Component Analysis (PCA) of Rattus norvegicus fat allows it to be classified with other animal fats.&#x0D; Conclusion: The Gas Chromatography-Mass Spectrometry (GC-MS) method, in combination with chemometric Principal Component Analysis (PCA), offered effective tools for the authentication of fatty acid of Rattus norvegicus.

KARAKTERISTIK FISIKOKIMIA EKSTRAK MADU DAN PROPOLIS TRIGONA SP. ASAL LOMBOK UTARA

Cultivation of honey and propolis Trigona sp. in the area of North Lombok Regency is growing, but has not equipped with scientific data regarding its physicochemical characteristics. This research aims to determine the physicochemical characteristics of honey and propolis extract of Trigona sp. from North Lombok. Physical parameters measured of the ethanol extract of honey and propolis Trigona sp. includes moisture content and ash content using gravimetric methods; Meanwhile, chemical parameters are identification of compounds using phytochemical screening methods and GC-MS (Gas Chromatography-Mass Spectrometry) instruments. Ethanol extract of honey Trigona sp. has moisture and ash content values of 9.38 ± 0.28% and 1.23 ± 0.02%, respectively; while the extract of propolis Trigona sp. containing water content and ash content of 11.64 ± 0.15% and 1.85 ± 0.02%. Ethanol extract of honey Trigona sp. identified positively containing flavonoid and alkaloid compounds, as well as 16 other compounds identified using GC-MS. Trigona sp. propolis extract contains flavonoids, alkaloids, tannins, saponins, and 10 compounds identified using GC-MS.

On the trail of primate scent signals: A field analysis of callitrichid scent-gland secretions by portable gas chromatography-mass spectrometry.

Chemosignals are mediators of social interactions in mammals, providing con- and hetero-specifics with information on fixed (e.g., species, sex, group, and individual identity) and variable (e.g., social, reproductive, and health status) features of the signaler. Yet, methodological difficulties of recording and quantifying odor signals, especially in field conditions, have hampered studies of natural systems. We present the first use of the Torion® portable gas chromatography-mass spectrometry (GC-MS) instrument for in situ chemical analysis of primate scents. We collected and analyzed swab samples from the scent glands and skin from 13 groups (57 individuals) of two sympatric species of wild emperor tamarins, Saguinus imperator, and Weddell's saddleback tamarins, Leontocebus weddelli (Callitrichidae). In total, 11 compounds of interest (i.e., probably derived from the animals) could be detected in the samples, with 31 of 215 samples containing at least one compound of interest. The composition of these 31 samples varied systematically with species, group, sex, and breeding status. Moreover, we tentatively identified seven of the compounds of interest as methyl hexanoate, benzaldehyde, ethyl hexanoate, acetophenone, a branched C15 alkane, 4-methoxybenzaldehyde, and hexadecan-1-ol. As the field of primate semiochemistry continues to grow, we believe that portable GC-MS instruments have the potential to help make progress in the study of primate chemosignaling in field conditions, despite limitations that we encountered. We further provide recommendations for future use of the Torion® portable GC-MS for in situ analyses.

Antiplasmodial Activity and Phytochemical Constituents of Selected Antimalarial Plants Used by Native People in West Timor Indonesia.

To document traditional antimalarial plants used by Tetun ethnic people in West Timor Indonesia and evaluate the antiplasmodial activity and phytochemicals of several plants that are widely used as oral medicine. A field study to document antimalarial plants followed by laboratory works to test antiplasmodial activity and identify the phytochemical constituents of some selected plants extract were applied. The inhibitory potency of ethanolic extracts of Strychnos ligustrina wood, roots of Calotropis gigantea, Fatuoa pilosa, and Neoalsomitra podagrica, whole plant of Cleome rutidosperma and Physalis angulata, stem barks of Alstonia spectabilis, Alstonia scholaris, Jatropha curcas and Plumeria alba, and leaves of Melia azedarach on the Plasmodium falciparum 3D7 strain in vitro were tested. Gas chromatography-mass spectrometry instrument was used to analyze the phytochemicals of the extracts. The Tetun ethnic people use 50 plant species as antimalarials. P. angulata, J. curcas, and A. spectabilis extracts show strong antiplasmodial activity with IC50 values of 0.22, 0.22, and 1.23 μg/mL, respectively; N. podagrica, A. scholaris, F. pilosa, and P. alba were moderate antiplasmodials with IC50 values of 11.60, 15.46, 24.92, and 36.39 μg/mL, respectively; and C. rutidosperma, M. azedarach, S. ligustrina, and C. gigantea were weak antiplasmodials with IC50 values of 54.25, 63.52, 63.91, and 66.49 μg/mL, respectively. The phytochemicals identification data indicate that these 11 plants contain alkaloids, terpenoids, steroids, coumarins, alcohols, thiols, phenolics, aldehydes, fatty acids, esters, and so forth. Plants widely used as antimalarials by the Tetun ethnic people is proven to have antiplasmodial activity.

ANALYSIS OF BIOACTIVE COMPONENTS FROM CHLOROFORM EXTRACT OF LYCOPERDON SP. (APIOPERDON)

Objective: The present work was done to find out various bioactive compounds present in the chloroform extract of Lycoperdon pyriforme using gas chromatography-mass spectrometry (GC-MS).&#x0D; Methods: L. pyriforme was collected cleaned to remove any dirt and oven dried at 60°C. The sample was then finely powdered and extracted with chloroform using Soxhlet apparatus. The chemical composition of chloroform extract was then analyzed using QP2010S-Shimadzu GC-MS instrument.&#x0D; Results: Chloroform extract resulted in the presence of 33 compounds with 1-Heneicosanol (11.17%) and E-15-Heptadecenal (11.08%) forming major compounds and 1-Tetradecanol (0.16%), Dichloroacetic acid, and decyl ester (0.15%) forming least.&#x0D; Conclusion: The results indicated the presence of a variety of compounds thus providing the information about various bioactive compounds present in Lycoperdon sp. and its further application in the field of pharmacology.

Investigating the Potential of an In-Situ Method for Monitoring the Malting of Barley Using Solid Phase Microextraction with a Portable Gas Chromatography Mass Spectrometry Instrument

An improved understanding of the malting process could have a significant impact on the efficient production of quality malt for the brewing industry. Analysis of volatile organic compounds produced during the malting process is one approach towards achieving this goal. In-situ methods avoid the possibility of contamination and chemical changes occurring during sample transport and storage. This paper describes the investigation of an in-situ sampling method for the detection of volatile organic compounds produced during the malting of barley. Solid Phase Microextraction Gas Chromatography Mass Spectrometry (SPME-GC/MS) was used to identify compounds. The investigated method involved the direct exposure of an SPME fiber in the kiln during barley malting. Using this method, compounds including aldehydes, ketones, and esters were detected. Some changes in volatile organic compound composition were observed during the production of pale malt at a commercial malting house.

Antiplasmodial Activity and Phytochemical Constituents of the Selected Antimalarial Plants Used by Native People in West Timor Indonesia

Objectives To document traditional antimalarial plants used by Tetun ethnic people in West Timor Indonesia and evaluate the antiplasmodial activity and phytochemicals of several plants that are widely used as oral medicine. Materials and Methods A field study to document antimalarial plants followed by laboratory works to test antiplasmodial activity and identify the phytochemical constituents of some selected plants extract were applied. The inhibitory potency of ethanolic extracts of Strychnos ligustrina wood, roots of Calotropis gigantea, Fatuoa pilosa, and Neoalsomitra podagrica, whole plant of Cleome rutidosperma and Physalis angulata, stem barks of Alstonia spectabilis, Alstonia scholaris, Jatropha curcas and Plumeria alba, and leaves of Melia azedarach on the Plasmodium falciparum 3D7 strain in vitro were tested. Gas chromatography-mass spectrometry instrument was used to analyze the phytochemicals of the extracts. Results The Tetun ethnic people use 50 plant species as antimalarials. P. angulata, J. curcas, and A. spectabilis extracts show strong antiplasmodial activity with IC50 values of 0.22, 0.22, and 1.23 μg/mL, respectively; N. podagrica, A. scholaris, F. pilosa, and P. alba were moderate antiplasmodials with IC50 values of 11.60, 15.46, 24.92, and 36.39 μg/mL, respectively; and C. rutidosperma, M. azedarach, S. ligustrina, and C. gigantea were weak antiplasmodials with IC50 values of 54.25, 63.52, 63.91, and 66.49 μg/mL, respectively. The phytochemicals identification data indicate that these 11 plants contain alkaloids, terpenoids, steroids, coumarins, alcohols, thiols, phenolics, aldehydes, fatty acids, esters, and so forth. Conclusion Plants widely used as antimalarials by the Tetun ethnic people is proven to have antiplasmodial activity.

Characterization of Fatty Acids in Cereals and Oilseeds from the Republic of Serbia by Gas Chromatography – Mass Spectrometry (GC/MS) with Chemometrics

This study investigates the potential of fatty acid profiles of various industrial crops to discriminate them based on their botanical origin. All of the analyzed plants were grown on experimental fields at Rimski Šančevi, Republic of Serbia. Cereal samples (corn, wheat, barley, and oat) were milled into flour and lipid fractions were extracted using n-hexane. Lipid fractions of oilseed samples (rape, flax, safflower, and pumpkin) were obtained by mechanical pressing. The fatty acids present in lipid fractions, were derivatized into corresponding volatile methyl esters (FAMEs) and determined on a gas chromatography/mass spectrometry instrument (GC-MS). Peaks of eluting compounds were simultaneously identified using mass spectra libraries, giving a match quality of over 90%. The peaks of molecular ions of methyl esters of 9 dominant fatty acids were extracted, and their abundances used to create numerical matrices for further data processing. Chemometric multivariate data analysis tools—principal component analysis (PCA), cluster analysis (CA), principal coordinate analysis (PCoA) and linear discriminant analysis (LDA), were used to extract significant variables, visualize discriminations, and classify between analyzed plant samples. The applied tools demonstrated separations of analyzed cereals in three groups: corn, oat and the samples of small grains—wheat and barley. In the case of oilseeds a clear separation between all four plant species was obtained. This work represents a new concept of the application of fatty acid analysis in developing authentication methods for industrial crops and their staple food products.

Occupational exposure to gaseous and particulate contaminants originating from additive manufacturing of liquid, powdered, and filament plastic materials and related post-processes

The aim of this study was to measure the concentrations of gaseous and particulate contaminants originated from additive manufacturing operations and post-processes in an occupational setting when plastics were used as feedstock materials. Secondary aims were to evaluate the concentration levels based on proposed exposure limits and target values and to propose means to reduce exposure to contaminants released in additive manufacturing processes. Volatile organic compounds were sampled with Tenax TA adsorption tubes and analyzed with a thermo desorption gas chromatography-mass spectrometry instrument. Carbonyl compounds were sampled with DNPH-Silica cartridges and analyzed with a high-performance liquid chromatography device. Particles were measured with P-Trak instrument and indoor air quality was sampled with IAQ-Calc instrument. Dust mass concentrations were measured simultaneously with a DustTrak DRX instrument and IOM-samplers. Particle concentrations were highest (2070-81 890 #/cm3 mean) during manufacturing with methods where plastics were thermally processed. Total volatile organic compounds concentrations, in contrast, were low (113–317 µg/m3 mean) during manufacturing with such methods, and vat photopolymerization. However, total volatile organic compounds concentrations of material jetting and multi jet fusion methods were higher (1,114–2,496 µg/m3 mean), perhaps because of material and binder spraying, where part of the spray can become aerosolized. Chemical treatment of manufactured objects was found to be a severe volatile organic compounds source as well. Formaldehyde was detected in low concentrations (3–40 µg/m3) in all methods except for material jetting method, in addition to several other carbonyl compounds. Notable dust concentrations (1.4–9.1 mg/m3) were detected only during post-processing of powder bed fusion and multi jet fusion manufactured objects. Indoor air quality parameters were not found to be notably impacted by manufacturing operations. Only low concentrations (below 2 ppm) of CO were detected during several manufacturing processes. All studied additive manufacturing operations emitted potentially harmful contaminants into their environments, which should be considered in occupational additive manufacturing and workplace design. According to the measured contaminant levels it is possible that adverse additive manufacturing related health effects may occur among exposed workers.

Stability control for breath analysis using GC-MS

Gas chromatography mass spectrometry (GC-MS) instruments provide researchers and clinicians with a vast amount of information on sample composition, thus these instruments are seen as gold standard in breath analysis research. However, there are many factors that can confound the data measured by GC-MS instruments. These factors will make interpretation of GC-MS data unreliable for breath analysis research. We present in this paper detailed studies of two of these factors: instrument variation over time and chemical degradation of known biomarkers during storage in sorbent tubes. We found that a single quadrupole MS showed larger variability in measurements than a quadrupole time-of-flight MS when the same mixture of chemical standards was analysed for a period of up to 8 weeks. We recommend procedures of normalising the data. Moreover, the stability studies of breath biomarkers like thioethers, previously found indicative of malaria, showed that there is a need to store the samples in sorbent tubes at low temperature, 6 °C, for no more than 20 days to avoid the total decay of the chemicals.

Evaluation of the reproducibility and repeatability of GCMS retention indices and mass spectra of novel psychoactive substances

Novel psychoactive substances (NPSs) are synthetically derived compounds designed to mimic the effects of other illicit drugs. An endless cycle of NPSs continually reach the drug market due to limitations in drug legislation creating two problems – non-availability of standards and multiple isobars indistinguishable even to high resolution mass spectrometry. Lacking standards, laboratories rely on published gas chromatography-mass spectrometry (GCMS) spectra to postulate compound identification. The ability to make such identifications provides vital investigative data and may help uncover new structural variants. However, central to such identifications is an understanding of how much spectral patterns vary across laboratories; the assumption that variation is minimized through the use of a standard tuning compound (PFTBA) has yet to be rigorously tested and demonstrated. In the present study, the variation of mass spectral fragmentation patterns characterized by percent relative abundance was evaluated using three GCMS instruments and 16 NPS compounds. The variation of retention indices was also studied. Retention indices showed <0.35% variation across all systems; mass spectral data showed much greater variation across all compounds and systems. Tuning frequency was one factor correlated with small variation. A means comparison of ion relative abundance did not clearly identify general patterns. Changes in identification of base ion peak was seen with three compounds. Base peak shifting on a single instrument, i.e. one instrument produced multiple base peak ions over the course of the study, generated a ripple effect, where variation across all relative abundances in the effected spectra increased. However, base peak shifting between instrument, i.e. each instrument produced a single base peak but the ion identity was not necessarily the same, did not produce these ripple effects. Either shifting base peak scenario had the potential to skew compound identification during untargeted analyses, which are common in a forensic drug chemistry setting.

Effect of Vermicompost and Spent Mushroom Compost on the Nutrient and Essential Oil Composition of Basil (Ocimum basilicum L.)

A pot-based experiment was conducted on the medicinal plant basil following a completely randomized design in the research farm of the Iran. Experimental treatments included supplementing the basic plant growth medium, a mixture of three parts soil and one part sand, with zero (control treatment), 10, 20, 30, 40 and 50 % volume ratios of vermicompost and washed and unwashed spent mushroom compost (SMC). Macronutrients including nitrogen, phosphorus, potassium and calcium and micronutrients such as iron, zinc, manganese and copper have been measured in the shoots of basil grown under above conditions. Essential oil of basil was extracted by Clevenger’s hydro-distillation apparatus and the ingredients of the essential oil have been identified using a gas chromatograph (GC) and a gas chromatography-mass spectrometry instrument (GC-MS). The results of micro and macronutrient contents in the shoot of basil showed the effectiveness of organic fertilizers (vermicompost and SMC) leading to an increase in those contents in plant. Organic fertilizers, when present in the plant growth medium, led to a higher nutrient content compared to the control treatment. The best results have often been achieved in vermicompost treatment. Increases in the major essential oil ingredients resulted from the elevated levels of vermicompost, and SMC. The highest concentration of myrsine (0.87), 1, 8-cineol (10.98) and sabinene (0.37) were found in the plants grown in a growth medium supplemented with 50 % of washed SMC which represented an increase of these compounds by 102 %, 96 %, and 116 % compared to the control treatment, respectively.

GAS CHROMATOGRAPHY - MASS SPECTROMETRY (GC-MS) IN ORGANIC GEOCHEMICAL INVESTIGATION OF CRUDE OILS FROM KIKINDA AND VELEBIT FIELDS IN SERBIA

In this work two crude oil samples were investigated to present the difference between biodegraded (Velebit) and non-degraded (Kikinda) oil. Two samples are from the Velebit oil–gas field and the Kikinda oil-gas field. These are two of the largest oil and gas deposits in the Serbian part of the Pannonian Basin. In the experimental part of this work, two samples of crude oil were separated by column chromatography. Saturated hydrocarbons were analyzed by gas chromatography-mass spectrometry instruments. Based on the abundance and distribution of biomarkers, it could be conclude that the distribution is typical of oil in both samples, with difference in the distribution of n-alkane. GC-MS chromatogram of n-alkanes and isoprenoids of saturated fraction isolated from Velebit crude oil show the distribution typical of oils altered by biodegradation.

An improved, automated whole air sampler and gas chromatography mass spectrometry analysis system for volatile organic compounds in the atmosphere

Abstract. Volatile organic compounds were quantified during two aircraft-based field campaigns using highly automated, whole air samplers with expedited post-flight analysis via a new custom-built, field-deployable gas chromatography–mass spectrometry instrument. During flight, air samples were pressurized with a stainless steel bellows compressor into electropolished stainless steel canisters. The air samples were analyzed using a novel gas chromatograph system designed specifically for field use which eliminates the need for liquid nitrogen. Instead, a Stirling cooler is used for cryogenic sample pre-concentration at temperatures as low as −165 °C. The analysis system was fully automated on a 20 min cycle to allow for unattended processing of an entire flight of 72 sample canisters within 30 h, thereby reducing typical sample residence times in the canisters to less than 3 days. The new analytical system is capable of quantifying a wide suite of C2 to C10 organic compounds at part-per-trillion sensitivity. This paper describes the sampling and analysis systems, along with the data analysis procedures which include a new peak-fitting software package for rapid chromatographic data reduction. Instrument sensitivities, uncertainties and system artifacts are presented for 35 trace gas species in canister samples. Comparisons of reported mixing ratios from each field campaign with measurements from other instruments are also presented.

Study of the Ignition Characteristics of Light Fractions of Crude Oil and Their Surrogate Fuels under a Range of Low-to-Medium Temperatures

To improve the self-ignition capability of oil reservoirs and build a detailed reaction kinetics mechanism of in situ combustion (ISC), ignition and reaction characteristics of light fractions of crude oil (boiling point of <100 °C, 100–125 °C, 125–150 °C, 150–175 °C, 175–200 °C, and 200–225 °C) were investigated on a rapid compression machine at compressed pressures of 20 bar and a compressed temperature range of 660–900 K, with a stoichiometric ratio of 1.0. According to our analysis with a gas chromatography–mass spectrometry instrument (GC-MS), cyclohexane, methyl-cyclohexane, p-xylene, and mesitylene were selected as surrogate fuels and were tested under the same conditions on a rapid compression machine (RCM). The experimental results show that three groups of light fractions, <100 °C, 100–125 °C, and 175–200 °C, display strong reactions at low and high temperatures and negative temperature coefficient (NTC) behavior. These phenomena imply that these reactive components can be used as possible promoters to accelerate the development of an ISC project and to improve the reaction speed of the entire process. Two groups of 125–150 °C and 200–225 °C fractions are difficult to ignite in the low-to-medium temperature range under the compressed pressure of 20 bar, but they can be ignited at relatively higher top dead center (TDC) temperature ranges under the compressed pressure of 30 bar. Moreover, the logarithm of ignition delays and the reciprocal temperature clearly show a linear relationship, meaning that the reactivity of these two groups is poor. The results obtained with these surrogate fuels match well with the experimental results of each light fraction.