Gas Chromatography-mass Spectrometry Method Research Articles

Local anesthetic marcaine-bupivacaine hydrochloride and its metabolites in Forensic Samples: A case study

The local anaesthetic bupivacaine and its metabolites such as Desbutyl bupivacaine, 3-hydroxybupivacaine, and 4-hydroxybupivacaine were extracted and found in the forensic sample from postmortem samples such as cerebrospinal fluid (CSF) and postmortem blood. To separate and detect the aforesaid substances in biological matrices, high-performance liquid chromatography (HPLC), gas chromatography-mass spectrometry (GC-MS) and ATR-FTIR methods were used. When a couple of husband and wife who were riding on the side of road by a motor cycle which was abruptly collided by an unknown motor cycle. The couple were injured, especially in the left leg of the lady was severe pain due to bone fracture. Both were immediately admitted in nearby a Government Hospital for treatment. Anaesthetic was injected to the lady before starting the procedure of surgery. Within a few minutes she suffered pulmonary consequence and the mortality immediately occurred. Due to a therapeutic amount of bupivacaine was given, postmortem samples CSF and blood were received at forensic laboratory and extracted using a liquid-liquid extraction method (LLE). Certain chromatographic techniques and ATR-FTIR method were used to separate and detect bupivacaine and its metabolites in a forensic sample.

Regression analysis for the determination of microplastics in sediments using differential scanning calorimetry.

This research addresses the growing need for fast and cost-efficient methods for microplastic (MP) analysis. We present a thermo-analytical method that enables the identification and quantification of different polymer types in sediment and sand composite samples based on their phase transition behavior. Differential scanning calorimetry (DSC) was performed, and the results were evaluated by using different regression models. The melting and crystallization enthalpies or the change in heat capacity at the glass transition point were measured as regression analysis data. Ten milligrams of sea sand was spiked with 0.05 to 1.5mg of microplastic particles (size: 100 to 200µm) of the semi-crystalline polymers LD-PE, HD-PE, PP, PA6, and PET, and the amorphous polymers PS and PVC. The results showed that a two-factorial regression enabled the unambiguous identification and robust quantification of different polymer types. The limits of quantification were 0.13 to 0.33mg and 0.40 to 1.84mg per measurement for semi-crystalline and amorphous polymers, respectively. Moreover, DSC is robust with regard to natural organic matrices and allows the fast and non-destructive analysis of microplastic within the analytical limits. Hence, DSC could expand the range of analytical methods for microplastics and compete with perturbation-prone chemical analyses such as thermal extraction-desorption gas chromatography-mass spectrometry or spectroscopic methods. Further work should focus on potential changes in phase transition behavior in more complex matrices and the application of DSC for MP analysis in environmental samples.

Establishment of a headspace-thermal desorption and gas chromatography-mass spectrometry method (HS-TD-GC-MS) for simultaneous detection of 51 volatile organic compounds in human urine: Application in occupational exposure assessment

Volatile organic compounds (VOCs) are a group of ubiquitous environment pollutants especially released into the workplace. Assessment of VOCs exposure in occupational populations is therefore a crucial issue for occupational health. However, simultaneous biomonitoring of a variety of VOCs is less studied. In this study, a simple and sensitive method was developed for the simultaneous determination of 51 prototype VOCs in urine by headspace-thermal desorption coupled to gas chromatography-mass spectrometry (HS-TD-GC-MS). The urinary sample was pretreated with only adding 0.50 g of sodium chloride to 2 mL of urine and 51 VOCs should be determined with limits of detection (LODs) between 13.6 ng/L and 24.5 ng/L. The method linearity ranged from 0.005 to 10 μg/L with correlation coefficients (r) of 0.991 to 0.999. The precision for intraday and inter-day, measured by the variation coefficient (CV) at three levels of concentration, was below 15 %, except for 4-isopropyl toluene, dichloromethane, and trichloromethane at low concentration. For medium and high levels, recoveries of all target VOCs were within the standard range, but 1,1-dichloropropene and styrene, which were slightly under 80 % at low levels. In addition, the proposed method has been used to determine urine samples collected in three times (before, during and after working) from 152 workers at four different factories. 41 types of prototype VOCs were detected in workers urine. Significant differences (Kruskal-Wallis chi-squared = 117.18, df = 1, P < 0.05) in the concentration levels of VOCs between the exposed and unexposed groups were observed, but not between the three sampling times (Kruskal-Wallis chi-squared = 3.39, df = 2, P = 0.183). The present study provides an alternative method for biomonitoring and assessing mixed exposures to VOCs in occupational populations.

Comparison of Approaches for Authentication of Commercial Terpinen-4-ol-type Tea Tree Oils Using Chiral GC/MS.

A global demand for tea tree oil (TTO) has resulted in increased adulteration in commercial products. In this study, we use a novel enantiomeric gas chromatography mass spectrometry method for chiral analysis of key terpenes ((±)-terpinen-4-ol, (±)-α-terpineol, and (±)-limonene) and quantification of components present at >0.01% to test different methods of identifying adulterated TTO. Data from authentic Australian (n = 88) and oxidized (n = 12) TTO samples of known provenance were consistent with recommended ranges in ISO 4730:2017 and previously published enantiomeric ratios, with p-cymene identified as the major marker of TTO oxidation. The 15 ISO 4730:2017 constituents comprised between 84.5 and 89.8% of the total ion chromatogram (TIC) peak area. An additional 53 peaks were detected in all samples (7.3-11.0% of TIC peak area), while an additional 43 peaks were detected in between 0 and 99% (0.15-2.0% of the TIC peak area). Analysis of nine commercial samples demonstrated that comparison to the ISO 4730:2017 standard does not always identify adulterated TTO samples. While statistical analysis of minor components in TTO did identify two commercial samples that differed from authentic TTO, the (+)-enantiomer percentages for limonene, terpinen-4-ol, and α-terpineol provided clearer evidence that these samples were adulterated. Thus, straightforward identification of unadulterated and unoxidized TTO could be based on analysis of appropriate enantiomeric ratios and quantitation of the p-cymene percentage.

Detection of Maize Mold Based on a Nanocomposite Colorimetric Sensor Array under Different Substrates.

This study developed a novel nanocomposite colorimetric sensor array (CSA) to distinguish between fresh and moldy maize. First, the headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC/MS) method was used to analyze volatile organic compounds (VOCs) in fresh and moldy maize samples. Then, principal component analysis and orthogonal partial least-squares discriminant analysis (OPLS-DA) were used to identify 2-methylbutyric acid and undecane as key VOCs associated with moldy maize. Furthermore, colorimetric sensitive dyes modified with different nanoparticles were employed to enhance the dye properties used in the nanocomposite CSA analysis of key VOCs. This study focused on synthesizing four types of nanoparticles: polystyrene acrylic (PSA), porous silica nanospheres (PSNs), zeolitic imidazolate framework-8 (ZIF-8), and ZIF-8 after etching. Additionally, three types of substrates, qualitative filter paper, polyvinylidene fluoride film, and thin-layer chromatography silica gel, were comparatively used to fabricate nanocomposite CSA combining with linear discriminant analysis (LDA) and K-nearest neighbor (KNN) models for real sample detection. All moldy maize samples were correctly identified and prepared to characterize the properties of the CSA. Through initial testing and nanoenhancement of the chosen dyes, four nanocomposite colorimetric sensitive dyes were confirmed. The accuracy rates for LDA and KNN models in this study reached 100%. This work shows great potential for grain quality control using CSA methods.

Development of a Thermal Separation Probe Gas Chromatography–Mass Spectrometry Method for Evaluating Wax–Resin Removal by Evolon® CR

Historically, many canvas paintings were infused with wax–resin mixtures that have discolored over time, distorting the aesthetics of the work, limiting treatment options, and introducing unstable materials into the object. Removal of the wax–resin is often desirable, but before works of art can be treated, a protocol to evaluate the efficacy of the treatment must be established. A mock-up painting was infused with a known amount of a wax–resin mixture made from beeswax and dammar; this material was then extracted through six intervals of exposure to solvent-loaded and dry sheets of Evolon® CR, a non-woven textile with a high sorbent capacity. Samples from the Evolon® CR sheets from each extraction round were analyzed using thermal separation probe gas chromatography–mass spectrometry (TSP-GC/MS). Normalization of peak areas related to beeswax and dammar to those of Evolon® CR revealed the relative amount of wax and resin removed throughout the extraction. The data show that, under these test conditions, the beeswax and dammar appear to be extracted with the same relative efficiency, information that cannot be provided through UV-induced visible fluorescence imaging of the Evolon® CR sheets or weight data alone, but which is critical to capture as it has implications for treatment success and the long-term stability of an artwork.

Experimental investigation on utilization of Sesbania grandiflora residues through thermochemical conversion process for the production of value added chemicals and biofuels

All the countries in the world are now searching for renewable, environmentally friendly alternative fuels due to the shortage and environmental problems related with the usage of conventional fuels. The cultivation of cereal and noncereal crops through agricultural activities produces waste biomasses, which are being evaluated as renewable and viable fossil fuel substitutes. The thermochemical properties and thermal degradation behavior of Sesbania grandiflora residues were investigated for this work. A fluidized bed reactor was used for fast pyrolysis in order to produce pyrolysis oil, char and gas. Investigations were done to analyze the effect of operating parameters such as temperature (350–550 °C), particle size (0.5–2.0 mm), sweeping gas flow rate (1.5–2.25 m3/h). The maximum of pyrolysis oil (44.7 wt%), was obtained at 425 °C for 1.5 mm particle size at the sweep gas flow rate of 2.0 m3/h. Fourier transform infrared spectroscopy and gas chromatography-mass spectrometry methods were used to examine the composition of the pyrolysis oil. The pyrolysis oil is rich with aliphatic, aromatic, phenolic, and some acidic chemicals. The physical characteristics of pyrolysis oil showed higher heating value of 19.76 MJ/kg. The char and gaseous components were also analyzed to find its suitability as a fuel.

Monitoring of changes in the concentration of volatile organic compound in beef irradiated with accelerated electrons

The need to develop safe methods for radiation processing of food products to improve their quality and extend their shelf life stimulates new scientific research aimed at increasing their effectiveness. Oxidation of lipids and proteins occurred under the impact of ionizing radiation in products with a high fat and water content, such as chilled meat and fish products, leads to the formation of volatile organic compounds in the product thus giving it a specific smell and taste. During storage, biochemical processes associated with microbial enzymatic activity and auto-oxidation develop in processed refrigerated products. These processes also modify the volatile organic compounds, which affect the organoleptic properties of the product. The method of gas chromatography-mass spectrometry was used to study the behavior of volatile compounds identified in irradiated beef samples both immediately after irradiation and four days later to determine the effective dose range for the radiation processing of beef. Monitoring of the content of volatile compounds in beef samples irradiated by 1-MeV electrons within a dose range from 0.25 to 5 kGy showed that the content of certain alcohols, aldehydes, and alkanes exhibited pronounced dose- and time-dependent character. The developed mathematical model describes the dependence of the concentration of volatile compounds identified immediately after irradiation in beef samples on the irradiation dose. The model is based on the simultaneous occurrence of two competing processes: the decomposition of compounds due to their oxidation and accumulation due to oxidation of other compounds after exposure to ionizing radiation. The results obtained revealed that the effective dosage range of radiation treatment lies between 250 and 1000 Gy.

Does the Quantification of Δ9-Tetrahydrocannabinolic Acid A in Serum/Plasma Provide Any Additional Information About Consumption Pattern from Drivers Under the Influence of Cannabis?

Introduction: Δ9-tetrahydrocannabinolic acid A (THCA-A) is one of the main ingredients of cannabis plants and is converted to the psychoactive substance Δ9-tetrahydrocannabinol (THC) by decarboxylation during heating above ∼90°C. During the consumption of cannabis, a varying proportion of THCA-A is absorbed into the body. Therefore, the quantification of THCA-A in serum/plasma might provide additional information on consumption behavior in driving under the influence of cannabis cases. Materials and Methods: In this study, an already established gas-chromatography mass-spectrometry (GC-MS) method for the quantification of THC, 11-OH-THC, and THC-COOH in serum and plasma samples was extended to include THCA-A. This validated method was then applied to 1228 routinely achieved serum/plasma samples from drivers suspected of cannabis consumption in Western Saxony. Two different grouping systems for chronic/occasional consumption, one system for acute/subacute consumption, Huestis formulas, and the cannabis influence factor (CIF) were used for evaluation. Results: Method validation showed appropriate results for forensic toxicological routine analysis. Limit of detection and lower limit of quantification (LLOQ) for THCA-A were 0.3 and 1.0 ng/mL, respectively. Reproducibility was <11% and accuracy ranged between 104% and 107%. THCA-A was stable in native samples at least for 2 weeks at room temperature or 4°C as well as 1 month at -20°C. Freeze-thaw stability for three cycles and processed sample stability over 3 days was proven. A total of 865 cases with a THC concentration above the German analytical cutoff of 1 ng/mL as well as the analytical LLOQs of 0.9 and 2.5 ng/mL for 11-OH-THC and THC-COOH, respectively, were included in further statistical analysis. In 407 (47.1%) of these samples, THCA-A was quantifiable. Different statistical analyses indicated a correlation between THCA-A and THC concentrations in cases of chronic and acute consumption. In addition, an increase of chronic and acute cases with increasing THCA-A concentrations was observed. However, no correlation between THCA-A and CIF was found. Discussion: These data show that THCA-A might be an additional indicative marker to provide information about consumption frequency and acuteness. Additional studies with known consumption frequencies and times are required to verify these findings.

Variability of Isoquinoline Alkaloid Profiles and Anticholinesterase Activities with Binding-Mode Predictions of Glaucium flavum Population.

In this study, phytochemical and biological activity studies supported by docking were carried out on a species of the genus Glaucium, a repository of isoquinoline alkaloids. The GC-MS (Gas Chromatography-Mass Spectrometry) method is used to characterize the isoquinoline alkaloids of Glaucium flavum Crantz. (Papaveraceae). G. flavum was collected from seven different regions of Türkiye (Antalya, Urla-Izmir, Mordogan-Izmir, Mugla, Assos-Canakkale, Karabiga-Canakkale, Giresun) and totally 17 compounds were detected by GC-MS. Glaucine was found to be the major constituent in the sample collected from Mugla, whereas isocorydine was recorded to be the principal alkaloid in other samples. Further fractionation studies on G. flavum collected from Antalya province in Southwestern Türkiye, yielded five major alkaloids (isocorydine 1, dihydrosanguinarine 2, glaucine 3, dehydroglaucine 4, protopine 5) which were characterized by spectroscopic methods. Anticholinesterase activities of the extracts and isolated alkaloids were also tested by in vitro Ellman method. The isolated compounds were also analyzed by a molecular docking technique to determine the binding orientations in the gorge of the active site of acetylcholinesterase (AChE) and a homology model of butyrylcholinesterase (BuChE). This is the first comparative investigation of the phytochemical composition and biodiversity of Glaucium flavum species growing in Türkiye.

Appropriate control measure design by rapidly identifying risk areas of volatile organic compounds during the remediation excavation at an organic contaminated site.

Many organic contaminated sites require on-site remediation; excavation remediation processes can release many volatile organic compounds (VOCs) which are key atmospheric pollutants. It is therefore important to rapidly identify VOCs during excavation and map their risk areas for human health protection. In this study, we developed a rapid analysis and assessment method, aiming to and reveal the real-time distribution of VOCs, evaluate their human health risks by quantitative models, and design appropriate control measures. Through on-site diagonal distribution sampling and analysis, VOCs concentration showed a decreasing trend within 5 m from the excavation point and then increased after 5 m with the increase in distance from the excavation point (p < 0.05). The concentrations of VOCs near the dominant wind direction were higher than the concentrations of surrounding pollutants. In contrast with conventional solid-phase adsorption (SPA) and thermal desorption gas chromatography-mass spectrometry (TD-GC/MS) methods for determining the composition and concentration of VOCs, the rapid measurement of VOCs by photo-ionization detector (PID) fitted well with the chemical analysis and modeling assessment of cancer/non-cancer risk. The targeting area was assessed as mild-risk (PID < 10ppm), moderate-risk (PID from 10 to 40ppm), and heavy-risk (PID > 40ppm) areas. Similarly, the human health risks also decreased gradually with the distance from the excavation point, with the main risk area located in the dominant wind direction. The results of rapid PID assessment were comparable to conventional risk evaluation, demonstrating its feasibility in rapidly identifying VOCs releases and assessing the human health risks. This study also suggested appropriate control measures that are important guidance for personal protection during the remediation excavation process.

Analysis of preservatives and fragrances in topical medical devices: The need for more stringent regulation.

Medical devices (MDs) have a long history of use, and come with regulatory frameworks to ensure user safety. Although topically applied MDs in the form of gels and creams might be used on damaged skin, their composition is often similar to that of cosmetic products applicable to intact skin, especially in terms of preservatives and fragrances. However, unlike cosmetics, these products are not subject to compound-specific restrictions when used in MDs. This study aimed to identify and quantify preservatives and fragrances in topically applied MDs and assess their safety towards the Cosmetic Regulation (EC) 1223/2009. Sixty-nine MDs available on the EU market were subjected to previously validated liquid chromatography tandem mass spectrometry (LC-MS/MS) and gas chromatography-mass spectrometry (GC-MS) methods to identify and quantify occurring preservatives and fragrances. Findings revealed that 32% of the examined MDs did not provide comprehensive ingredient lists, leaving users uninformed about potential risks associated with product use. Furthermore, 30% of these MDs would not meet safety standards for cosmetic products and, most significantly, 13% of the analysed samples contained ingredients that are prohibited in leave-on cosmetics. Results highlight the pressing demand for more stringent requirements regarding the labelling and composition of MDs to enhance patient safety. Improved regulation and transparency can mitigate potential risks associated with the use of topically applied MDs.

Quantifying terpenes in tomato leaf extracts from different species using gas chromatography-mass spectrometry (GC-MS)

Terpenes play a vital role in plant defense; tomato plants produce a diverse range of terpenes within specialized glandular trichomes, influencing interactions with herbivores, predators, and pollinators. This study employed two distinct methods, namely leaf dip and maceration, to extract trichomes from tomato leaves. Terpene quantification was carried out using Gas Chromatography-Mass Spectrometry (GC-MS). The leaf dip method proved effective in selectively targeting trichome content, revealing unique extraction patterns compared to maceration. The GC-MS method demonstrated high linearity, accuracy, sensitivity, and low limits of detection and quantification. Application of the method to different tomato species (Solanum pennellii, Solanum pimpinellifolium, Solanum galapagense, Solanum habrochaites, and Solanum lycopersicum) identified significant variation in terpene content among these species, highlighting the potential of specific accessions for breeding programs. Notably, the terpene α-zingiberene, known for its repellency against whiteflies, was found in high quantities (211.90–9155.13 μg g−1) in Solanum habrochaites accession PI209978. These findings provide valuable insights into terpenoid diversity for plant defense mechanisms, guiding future research on developing pest-resistant tomato cultivars. Additionally, the study underscores the broader applications of terpenes in agriculture.

Integrated Fruit Ripeness Assessment System Based on an Artificial Olfactory Sensor and Deep Learning.

Artificial scent screening systems, inspired by the mammalian olfactory system, hold promise for fruit ripeness detection, but their commercialization is limited by low sensitivity or pattern recognition inaccuracy. This study presents a portable fruit ripeness prediction system based on colorimetric sensing combinatorics and deep convolutional neural networks (DCNN) to accurately identify fruit ripeness. Using the gas chromatography-mass spectrometry (GC-MS) method, the study discerned the distinctive gases emitted by mango, peach, and banana across various ripening stages. The colorimetric sensing combinatorics utilized 25 dyes sensitive to fruit volatile gases, generating a distinct scent fingerprint through cross-reactivity to diverse concentrations and varieties of gases. The unique scent fingerprints can be identified using DCNN. After capturing colorimetric sensor image data, the densely connected convolutional network (DenseNet) was employed, achieving an impressive accuracy rate of 97.39% on the validation set and 82.20% on the test set in assessing fruit ripeness. This fruit ripeness prediction system, coupled with a DCNN, successfully addresses the issues of complex pattern recognition and low identification accuracy. Overall, this innovative tool exhibits high accuracy, non-destructiveness, practical applicability, convenience, and low cost, making it worth considering and developing for fruit ripeness detection.

Alterations of circulating free fatty acids in patients with pemphigus vulgaris.

Free fatty acids (FFA) have gained research interest owing to their functions in both local and systemic immune regulation. Changes in the serum levels of anti-inflammatory short chain fatty acids (SCFA), primarily derived from the gut microbiota, and pro-inflammatory medium (MCFA) and long (LCFA) chain fatty acids, derived from either the gut microbiota or the diet, have been associated with autoimmunity. Circulating FFA were retrospectively analysed by a gas chromatography-mass spectrometry method in the serum of 18 patients with pemphigus vulgaris (PV) at the baseline and 6 months (n = 10) after immunosuppressive treatments, and 18 healthy controls (HC). Circulating FFA were correlated with the Pemphigus Disease Area Index (PDAI) and serum concentrations of interferon-gamma (IFN-γ), Interleukin (IL)-17A, IL-5, IL-10 and IL-21. Principal Component analysis computed on FFA abundances revealed significant differences in the profile of SCFA (p = 0,012), MCFA (p = 0.00015) and LCFA (p = 0,035) between PV patients and HC, which were not significantly changed by immunosuppressive treatments. PV patients showed a significantly lower serum concentration of propionic (p < 0.0005) and butyric (p < 0.0005) acids, SCFA with anti-inflammatory functions, while hexanoic (p < 0.0005) and hexadecanoic (p = 0.0006) acids, pro-inflammatory MCFA and LCFA respectively, were over-represented. Treatments induced a significant decrease of hexanoic (p = 0.035) and a further increase of hexadecanoic (p = 0.046) acids. Positive correlations emerged between IFN-γ and acetic acid (Rho = 0.60), IFN-γ and hexanoic acid (Rho = 0.46), IL-5 and both hexadecanoic acid (Rho = 0.50) and octadecanoic acid (Rho = 0.53), butyric acid and PDAI (Rho = 0.53). PV was associated with a remarked imbalance of circulating FFA compared to HC. The serum alterations of SCFA, MCFA, and LCFA may contribute to promoting inflammation in PV. Deeper insights into the immunomodulatory functions of these molecules may pave the way for personalized dietary interventions in PV patients.

Effects of Packaging Material Type, Storage Time and Lipid Content on Phthalate Migration in Smoked Fish Meat

The objective of this study is an investigation of the influence of six different plastic packages (polyethylene terephthalate, high-density polyethylene, biodegradable high-density polyethylene, low-density polyethylene, polypropylene and polyamide polyethylene) on the migration of phthalate residues in smoked carp, trout and salmon stored at −18 °C for three and six months. Six phthalate residues concentrations were determined using the gas chromatography-mass spectrometry method. Diisobutyl phthalate (DIBP) and dibutyl phthalate (DBP) migrated the most into salmon meat from PAPE packaging after six months of storage, reaching 73.77 μg/kg and 78.45 μg/kg, respectively. The highest concentrations of bis(2-ethylhexyl) phthalate (DEHP) after six months of storage were present in salmon meat packed in polyamide polyethylene (253.56 μg/kg) and the lowest in carp meat packages in polypropylene (157.72 μg/kg). Phthalate residues in all the samples showed higher levels after three and six months of storage compared to the control sample. Among the investigated phthalates, polypropylene was the material with the lowest migration into fish meat. A further amount of DEHP migration in the fish was detected with a higher fat content. We acknowledge that levels of phthalates should be monitored, and research in this field should be continued, especially since there are no legal restrictions regarding the maximum level of phthalates in food.

Analysis of biopesticide active compounds in Barringtonia asiatica L. Kurz using the GC-MS method

The objective of this study is to use gas chromatography mass spectrometry (GC-MS) to discover the biopesticide active components in bitung seeds (Barringtonia asiatica L. Kurz). research being carried out at Gadjah Mada University Integrated Research and Testing Laboratory in Yogyakarta (LPPT-UGM). The research was conducted from March 1, 2023, until April 2, 2023. The Rf number, color test, fragmentation pattern, and solubility of B. asiatica L. Kurz seed extract were the assessment standards that were used. Based on the area’s chromatogram results, quantitative analysis was carried out to ascertain the quantity of organic molecules that comprise secondary metabolites. After being gas chromatographically separated, the number of organic components that comprise secondary metabolites was enumerated in order to perform a qualitative study. The findings of tests using extracts from seeds of B. asiatica by Gas Chromatography-Mass Spectrometry (GC-MS) yield substances that are secondary metabolites, namely: Octasiloxane, hexadecamethyl-1,1,3,3,5,7,7,9,9,11,11,13,13,15,15-, has the chemical formula C16H50O7Si8 and has a heavy molecular mass of 578 g/mol. The formula chemistry of hexasiloxane, 1,1,3,3,5,7,7,9,9,11,11-dodecamethyl -, is C12H38O5Si6 heavy molecule 430 g/mol, while the formula chemistry of heptasiloxane, 1,1,3,3,5,5,7,7,9,9,11,11,13,13-tetradecamethyl, is C14H44O6Si7 heavy molecule 504 g/mol.

Elucidating the significant roles of root exudates in organic pollutant biotransformation within the rhizosphere

Biotransformation of organic pollutants is crucial for the dissipation of environmental pollutants. While the roles of microorganisms have been extensively studied, the significant contribution of various root exudates are still not very well understood. Through plant growth experiment, coupled with gas and liquid chromatography-mass spectrometry methods, this study examined the effect of the presence of M. sativa on microbial-associated biochemical transformation of petroleum hydrocarbons. The results of this study revealed that the concentration of exudates within the soil matrix is a function of proximity to root surfaces. Similarly, biodegradation was found to correlate with distance from roots, ranging from ≥ 90% within the rhizosphere to < 50% in bulk soil and unplanted control soil. Most importantly, for the first time in a study of an entire petroleum distillate, this study revealed a statistically significant negative correlation between root exudate concentration and residual total petroleum hydrocarbons. While not all the compounds that may influence biodegradation are derived from roots, the results of this study show that the presence of plant can significantly influence biodegradation of hydrocarbon pollutants through such root exudation as organic acids, amino acids, soluble sugars and terpenoids. Therefore, root exudates, including secondary metabolites, offer great prospects for biotechnological applications in the remediation of organic pollutants, including recalcitrant ones.

Identification of thermolabile positional isomers of N-(2-hydroxybenzyl)-2-(dimethoxyphenyl)ethanamines (NBOH series) using chromatography and mass spectrometry methods.

Among N-((2-substituted)benzyl)phenylethanamines, N-(2-hydroxybenzyl)phenylethanamines are a special type of compounds which are thermolabile and degrade in the course of analysis by means of gas chromatography-mass spectrometry (GC-MS). This can lead to substantial errors, in the identification of legally controlled compounds of this series containing methoxy groups at positions 2 and 5 of the benzene ring of the phenylethyl fragment by GC-MS, which is commonly used in forensic and toxicological laboratories. Exemplified by the five isomeric 2-(dimethoxyphenyl)-N-(2-hydroxybenzyl)ethanamines, it was shown that their derivatization with trifluoroacetic anhydride (same as in the case of the N-(2-methoxybenzyl)-, N-(2-fluorobenzyl)-, N-(2-chlorobenzyl)-, and N-(2-bromobenzyl)substitutes phenylethanamines [NBOMe, NBF, NBCl, and NBBr, respectively] series described earlier) results in only one product, N-monosubstituted derivative, for each positional isomer within a series, which makes it possible to reliably identify each compound by the GC-MS method. In addition, chromatographic conditions for sufficient separation of trifluoroacetyl derivatives of these positional isomers of the NBOH series in 25 min are proposed, which is an important aspect for analysis in forensic laboratories engaged in the determination of narcotic drugs and new psychoactive substances. As an alternative approach, a method for identifying positional isomers of the NBOH series by the high-performance liquid chromatography-high-resolution mass spectrometry (HPLC-HRMS) method without derivatization is proposed.

Sodium Methoxide Catalyzed Preparation of Nitrogen Compounds from Palm Oil Methyl Esters as Corrosion Inhibitor

This research was conducted to study preparation of nitrogen compounds by reacting palm oil derived methyl esters and diethanolamine using sodium methoxide as a catalyst. The chemical composition of the product was analyzed using the gas chromatography-mass spectrometry (GC-MS) method. The product was then applied as a corrosion inhibitor for mild steel in CO2 saturated 3% NaCl solution. Experimental results indicate that the reaction product contains six nitrogen compounds with a relative percentage of 63.7%, and the rest 36.7% are a mixture of unreacted diethanolamine and unreacted methyl esters. The results of the corrosion experiments show that the product obtained exhibited appreciably high performance as reflected by a percentage of protection (%P) of 96.85%. The performance of the product as a corrosion inhibitor is also supported by the SEM image of the mild steel sample, which shows that the surface of the sample is well protected. The results of this work demonstrate that nitrogen compounds obtained have promising potential as corrosion inhibitors, particularly to prevent corrosion by CO2 gas.