Gas Chromatography Coupled To Mass Spectrometer Research Articles

Gas Chromatography-Mass Spectroscopy and Fourier Transform Infrared Profiling of the Bioactive Compounds Present in Methanol Leaf Extract of Solanum Aethiopicum from Imo State, Nigeria

The study aimed to access the bioactive compounds and functional groups present in Solanum aethiopicum using the Gas Chromatography coupled with mass spectrometer (GCMS) and Fourier Transform Infrared Spectroscopy (FTIR). The GCMS showed Solanum aethiopicum showed a total of thirty-seven bioactive compound with the highest abundance being Squalene (21.13%), Palmitoleic acid (16.63%), 13-Octadecenal (16.63%) and 9-Octadecenoic acid (17.62%). Fourier Transform Infrared Spectroscopy of Solanum aethiopicum showed the presence of functional groups which include alkanes, alkenes, alkynes, primary (10) and secondary (20) amines, amides, imino, epoxy, peroxides, carboxylic esters, ethers, primary (10), secondary (20) and Tertiary (30) alcohols, phenols, aldehydes, thiols, cyanate, isocyanates and alkyl halides. These bioactive compounds with reference to literature revealed a variety of biological functions spanning across antibacterial, anti-inflammatory, anti-oxidant, analgesic, antimalarial, antifungal, anti-tumour, neuroprotective, anti-tumour, anti-cancer, anti-seizure, anti-allergy, anti beta-amyloid protein aggregation.

A systematic derivatization technique for characterization of ethoxylates by GC and GCMS

AbstractEthoxylation is one of the common industrial process in which ethylene oxide (EO) is added to compounds containing active hydrogen atom (OH, COOH, SH, NH, etc.) to form surfactants. Alcohol ethoxylates are a major class of non‐ionic surfactants composed of an alkyl chain combined with few EO units. They are widely used in homecare products, personal care products, textiles, oilfield, construction, lubricants, food, paper, leather. The analysis of these ethoxylates possess several challenges since they contain ‘n’ number of EO units (n > 1). With increase in “n,” the product becomes more and more viscous and the boiling point increases making it difficult to analyze by normal gas chromatography (GC) technique. This paper describes a method of derivatizing these ethoxylates so that they can be eluted on a high temperature GC. BSTFA (N, O‐bis (trimethylsilyl) trifluoroacetamide) is used as the derivatizing agent (silylating agent). The ethoxylate combines with BSTFA to form the corresponding trimethylsilylated (TMS) product, which have comparatively lower boiling point. Thus, we detect trimethyl silyl product, which is the resemblance for the ethoxylated product. In this paper, we present a quantitative GC method for the ethoxylates of a few simple alcohols (2‐ethyl hexanol, glycerin), and complex vegetable oils (castor oil). The products formed during the reaction have also been identified on a gas chromatograph coupled with mass spectrometer (GCMS). GCMS shows the mass corresponding to the TMS derivatized product. The derivatization technique not only helps in increasing the volatility of these compounds but also improves the chromatographic efficiency, selectivity, and enhances the detectability.

Assessment of Organochlorines Pesticides Residues in Water, Fish and Sediment Samples from Wurbo Lake, Bali, Taraba State, Nigeria

Organochlorines pesticides (OCPs) have been used worldwide, particularly in many African countries as in Nigeria for the control of pests. OCPs are characterized by their bioaccumulation in the environment, especially in the food chain, where they find their way into the human body. The research was aim to estimate the residual concentrations of different OCPs in water, fish and sediment from Kundi Lake to find out the extent of pesticide contamination and accumulation. The water sample was subjected to liquid-liquid extraction method while the fish and the sediment samples were subjected to soxhlet extraction. The extracts were later analysed for organochlorines pesticide residues using Gas-Chromatography coupled with mass spectrometer (GC-MS). The average length, average weight and condition factor of the studied fish species were measured. The Mormyrus rume had the highest average length of 17.12±0.05 cm, and average weight of 195.36±0.05 g follow by Clarias gariepinus which had the average length of 16.83±0.01 cm, and average weight of 189.43±0.03 g. Tilapia zilli was the least species of fish sample with a length of 12.75±0.03 cm and average weight of 102.21±0.02 g. Also, all the fish species sampled in this present study had condition factors>1. Based on the results obtained from all samples, it was found that the levels of organochlorine pesticides residues in water were generally below MRL as compared with FAO/WHO (0.5ppm). In fish samples, highest concentration of pesticide residues in Mormyrus rume follow by Clarias gariepinus, while the Tilapia zilli recorded low concentration of the pesticide residues. The Endosulfan II recorded high concentration of 4.68 ppm in Mormyrus rume follow by Endrin which recorded the concentration of 2.75 ppm, Aldrin 1.78 ppm and Atrazine 1.72 ppm all in Mormyrus rume. In Clarias gariepinus, Simazine 1.56 ppm follows by Endosulfan I 1.28 ppm while In Tilapia zilli, Endosulfan II 1.16 ppm follows by Atrazine 0.91 ppm and Beta Lindane 0.81 ppm. The results indicate that the area is contaminated with high levels of these pesticides in fish and sediment which may pose a great danger to the environment. Regular monitoring is therefore required to control the levels of pesticide residues in the water bodies.

Antimicrobial Activity of Cosmos caudatus Against Staphylococcus aureus and Escherichia coli.

Malaysia is known for its richness in ecosystem including medicinal plants and herbs. The use of traditional herbs for medical purposes has been practiced for ages without any proper understanding on how they work. This study aims to produce extract from the leaves of Cosmos caudatus (Ulam Raja) and to investigate the antimicrobial activity of the produced extract against Staphylococcus aureus and Escherichia coli. Ethanolic Soxhlet extraction was carried out to obtain the leaves extract. Product from extraction process was subsequently tested using the Kirby-Bauer disk diffusion test to determine its inhibitory effects against S. aureus and E. coli. Finally, the bioactive compounds in extracts were profiled using gas chromatography coupled with mass spectrometer (GC-MS). Findings showed ethanol is suitable to be used in obtaining extract from the leaves of C. caudatus. The extract produced was dark green and was able to inhibit the growth of both Gram-positive (S. aureus) and Gram-negative (E. coli) bacteria. The size of inhibition zones ranging from 22 to 24 mm. The zones of inhibition produced by C. caudatus extract in this study are comparable to commercial antiseptic tested simultaneously in the experiment. Analysis of extract using GC-MS revealed several bioactive compounds including palmitic acid, stigmasterol, phytol and neophytadiene These compounds are well known for their medicinal and therapeutic properties such as antimicrobial, antioxidants and antitumor. Additionally, these bioactive compounds are commonly used as ingredients in commercial antiseptics and disinfectants. This study therefore has proven the medicinal properties of C. caudatus. Findings from this study can be used to develop plant-based pharmaceutical products which are cheaper, safer, and more environmentally friendly.

Determination of organochlorine pesticides residues in water, fish and sediment samples from River Tella, Gassol, Taraba State, Nigeria

The study was aimed at determining the levels of organochlorine pesticides residues in water, sediment and fish species at River Tella to find out the extent of pesticide contamination and accumulation in the river. Total of fourteen (14) organochlorine pesticide residues were analyzed which include Delta lindane, Alpha Lindane, Beta Lindane, Gamma Lindane, Heptachlor, Aldrin, Heptachlor Epoxide, Endosulfan I, Endosulfan II, P’P-DDE, P’P-DDD, P’P-DDT and Methoxychlor. The water sample was subjected to liquid-liquid extraction method while the fish and the sediment samples were subjected to soxhlet extraction. The extracts were later analyzed for organochlorine pesticide residues using Gas-Chromatography coupled with mass spectrometer (GC-MS). The study has revealed that the level of pesticides residues in water was less than that of fish and sediment which was also below the WHO/FAO values. It was also observed that high concentrations recorded were recorded in high in Gamma Lindane (24.71), follow by Alpha Lindane (23.70) and Beta Lindane (4.50). Mormyrus rume follow by Claria gariepinus while the Tilapia zilli recorded low concentration of the pesticide residues. The Aldrin recorded high concentration of 5.11 ppm in Mormyrus rume follow by Endosulfon II which recorded the concentration of 25.03 ppm also in Mormyrus rume. Endrin also recorded the concentration of 4.88 ppm in Clarias. gariepinus. The lowest pesticide residues was recorded in p,p'-DDD (0.01 ppm), p,p'-DDT (0.03 ppm), Methoxychlor (0.01 ppm). The Heptachlor epoxide and P’P-DDE were not detected in water sample. The presence of high concentration in fish may pose a great danger when these fish are being consumed over time. Regular monitoring is therefore required to control the levels of pesticide residues in the water bodies. The measurement of the fish showed that Clarias gariepinus had the average length of 15.89 cm, and average weight of 179.87 g. Mormyrus rume had the average length of 15. 18 cm, and average weight of 210. 54g. Tilapia zilli was the least species of fish sample with a length of 12.96 cm and average weight of 96.88 g. The water quality parameters of the river were also studied, which recorded the temperature of 28.89 oC was recorded, pH value of 9.01, Conductivity value of 40.11, DO value of 6.14 and TDS of 2.35.

GC-MS analysis and anti-malodor activity of Indonesian patchouli leaves essential oil [Pogostemon cablin (Blanco) Benth.] against Corynebacterium Sp isolate

Most of the studies report that species of the Corynebacterium genus are generally causal bacteria of axillary odor, by converting odorless secretions compounds into odorous volatile molecules. The aim of this work was to provide information on the chemical compounds in the essential oil of Indonesian patchouli leaf (Pogostemon cablin (Blanco) Benth) that demonstrated the antibacterial activity against Corynebacterium sp. clinical isolate. The Corynebacterium sp. was isolated from basketball players' armpits and identified by observing the specific colonies characteristics on the blood agar. The chemical compounds were characterized using gas chromatography coupled to mass spectrometer (GC-MS). The antibacterial activity was performed according to the procedures of the Clinical and Laboratory Standards Institute. According to GC-MS result, the essential oil of Indonesian patchouli leaf presented 62 different compounds with the majorities as the following compounds: patchouli alcohol (21.00%), 1H-benzocycloheptene, 2,4a, 6,6,7,8-hexahydro-3,5,5,9-tetramethyl- (18.70%), caryophyllene (5.36%), seychellene (4.24%) and cyclohexene,1-methyl-4-(5-methyl-1-methylene-4-hexenyl) (3.01%). The integration of these compounds potentiates the antibacterial activity of the essential oil with lower concentration than 10 % v/v. Therefore, the essential oil of Indonesian patchouli leaf presented the significant antibacterial activity against Corynebacterium sp. as the causative agent of axillary odor.

4. 1-Etylo-2-pirolidon. Metoda oznaczania w powietrzu na stanowiskach pracy z zastosowaniem chromatografii gazowej

1-Ethyl-2-pyrrolidone (NEP) is a colorless liquid with ammonia-like odor. It belongs to the organic compounds from the lactam group, i.e., the ethyl derivative of 2-pyrrolidone. 1-Ethyl-2-pyrrolidone, due to similar physicochemical proper-ties, is used in industry as a substitute for 1-methyl-2-pyrrolidone (NMP). It is used as a solvent in polymer, petroche-mical, paint and varnish, and electronic industries. Moreover, it has been used as a cleaning agent for removing paints, varnishes, adhesives, oil or grease. 1-Ethyl-2-pyrrolidone can be absorbed through the skin as well as through inhalation and food. The aim of the this study was to develop and validate a method for determining 1-ethyl-2-pyrrolidone in work-place air. The developed method of NEP determination consists in adsorption of vapors of this substance on coconut shell charcoal, extraction with a dichloromethane and chromatographic analysis of the obtained solution. The study was performed using a gas chromatograph coupled with mass spectrometer (GC-MS), equipped with a polar ZB-WAXplus capillary column (length 60 m, diameter 0.25 mm and the film thickness of the stationary phase 0.5 µm). The developed method is linear in the concentration range of 15.0–320.0 µg/ml, which corresponds to the range of 1.5–32.0 mg/m3 for a 10-L air sample. The analytical method described in this paper makes it possible to determine 1-ethyl-2-pyrrolidone in workplace air in the presence of comorbid substances. The method is precise, accurate and it meets the criteria for procedure for measuring chemical agents listed in Standard No. PN-EN 482. Developed method of determining 1-ethyl- 2-pyrrolidone at workplace air has been recorded as an analytical procedure (see Appendix). This article discusses the problems of occupational safety and health, which are covered by health sciences and environmental engig.

Anthropic action affects the cuticular chemical profile of social wasps

As a result of environmental change by anthropic action, animal species that inhabit these areas may suffer the effects of it on their phenotypes as a consequence of adapting to these conditions. In the case of social wasps, cuticular chemical compounds may be influenced, since these vary depending on genetic and environmental factors. However, few studies have investigated the synanthropic effects over the cuticular surface of social wasps. Therefore, the aim of this study was to investigate how cuticular compounds vary according to the different degrees of human activity and test the hypothesis that cuticular compounds of social wasps are affected by the level of anthropic activity in which their nests are found. Data on the cuticular chemical compounds composition of colonies of 3 species of social wasps were used along with the level of anthropization of their nesting sites in four municipalities in the state of Mato Grosso do Sul, Brazil. From the geographical coordinates of the sampling sites, the percentages of urban construction areas, agriculture, water body, vegetation and exposed land were calculated, and the nesting sites of the colonies were classified as more or less anthropized areas. The chemical profile was determined by extraction of cuticular compounds and analyzed by Gas Chromatography coupled to Mass Spectrometer (GC-MS). The results show that the cuticular chemical composition of the individuals of these species is affected by the level of anthropization in their nesting sites, with a qualitative and quantitative variation that must be tied not only to genetic differences, but, above all, to the local environmental conditions to which their colonies are subjected.

Identification of recycled polyethylene and virgin polyethylene based on untargeted migrants

With increasing attention to recycled polyethylene (PE), its safety as a food contact material has become non-negligible. In this study, we report an untargeted gas chromatography coupled to mass spectrometer (GC-MS) analysis combined with multivariate data analysis for discriminating recycled PE from virgin PE. 80 (semi-)volatile migrants were identified, including 10 hydrocarbons, 29 esters, 3 aldehydes, 9 alcohols, 2 ethers, 4 acids, 4 benzene derivatives, 4 ketones, 3 amides, 2 piperazine derivatives and 10 unknowns. The hydrocarbons in virgin samples showed a greater variety and abundance than those in recycled samples. Based on orthogonal partial least squares discriminant analysis (OPLS-DA) and non-parametric test, 38 markers were selected to establish a classification model to identify recycled and virgin PE. These markers mainly derived from additives, daily chemical products related and food related input pollutants, most of which were rich in recycled samples. Furthermore, in classification models, linear discrimination analysis (LDA) showed higher stability and predictability than soft independent modelling of class analogy (SIMCA). The average accuracy of training and prediction set reached 100% and 92%, respectively, in LDA model. The identification of recycled PE and virgin PE based on migration of untargeted substances is feasible.

Phytochemical, antioxidant and antibacterial study of essential oils of the leaves and fruits of Juniperus Phoenicea

Extracts from aromatic and medicinal plants contain a variety of phenolic compounds as well as essential oils (EO's) which are believed to have antioxidant and microorganism inhibiting activities. Essential oils of leaves and fruits of Juniperus Phoenicea collected in the region of Midelt (Morocco) were obtained by the technique of hydrodistillation and analyzed by Gas Chromatography coupled to Mass Spectrometer (GC-MS). The yield of essential oil is variable depending on the part of the plant studied; it is 0.5% for leaves and 0.14% for fruits. The main compounds of the essential oil of the leaves are α- pinene, Caryophyllene and β- phellandrene while the EO of the fruits is largely dominated by α- pinene. These EOs have a marked antioxidant activity but remains lower than that of the decocted leaves and fruits of the same plant studied, this activity measured by the DPPH method. An antibacterial activity of these EOs was also demonstrated by the aromatogram method, with a strong inhibitory activity for the fruit EO compared to that of the leaves.

Furan. Determination in workplace air with gas chromatography

Furan is colorless, highly volatile and flammable liquid with a specific ether odor. In nature it occurs in some species of wood, it is formed during burning process of wood, tobacco, fuels and also in thermal food processing. In industry furan is used as an intermediate in organic synthesis, resins solvent, during production of lacquer, drugs, stabilizers, insecticides and also in production of chemical compounds which have polymeric and coordination structure. Carcinogenic effect on animals was a base of recognition that furan is a substance which is probably also carcinogenic on humans. The aim of this study was to develop and validate a method of determining furan in workplace air. Developed determination method of furan relies on vapor absorption of this substance on coconut shell charcoal. Furan was extracted by 5% butan-1-ol solution in toluene. Obtained solution was analyzed with chromatography. The study was performed with gas chromatograph coupled with mass spectrometer (GC-MS), equipped with non-polar HP-PONA capillary column (length 50 m, diameter 0.2 mm and the film thickness of the stationary phase 0.5 µm). Developed method is linear in the concentration range of 0.05–1.0 µg/ml, which is equivalent to the range of 0.005–0.1 mg/m3 for 10-L air sample. The analytical method described in this paper makes it possible to determine furan in workplace air in the presence of comorbid substances. The method is precise, accurate and it meets the criteria for procedures for determining chemical agents listed in Standard No. PN-EN 482. The developed method of determining furan in workplace air has been recorded as an analytical procedure (see Appendix). This article discusses the problems of occupational safety and health, which are covered by health sciences and environmental engineering.

Identification of Extractives from Various Poplar Species

Fast-growing poplar trees from plantations are the source of inexpensive wood that is intended mainly for chemical processing in the pulp and paper industry. Their potential as raw material for biofuel manufacturing is widely discussed as well. The detailed chemical composition of this raw material is therefore an important question. Five species of poplars were investigated: Populus alba, P. maximowiczii, P. trichocarpa, P. nigra, andP. tremula. Wood is a material consisting mainly of lignocellulose, but there are also many extractives. In temperate zone climate they typically represent up to 5% of wood mass. Their identification is difficult, due to various classes of compounds and great number of individual ones. These compounds can affect the properties of wood—its resistance to biotic agents and suitability to enzymatic treatment towards biofuels. Gas chromatography coupled with mass spectrometer (GC-MS) was used to analysis of extractives in various species of poplar wood. Compounds from several classes were identified like phenols, fatty acids, and their derivatives, sterols. Their identification was discussed along with estimation of their content in wood of investigated species.

Estudo e influência dos óleos essenciais de cravo, canela e laranja na preparação de filmes de poli (ácido lático): desenvolvimento de embalagens ativas

O poli (ácido lático) – PLA é um polímero biocompatível e biodegradável com algumas propriedades semelhantes aos polímeros convencionais, destacando-se em diversas aplicações, dentre elas, a indústria de embalagens. A substituição dos aditivos convencionais por componentes naturais como os óleos essenciais, vem tornando-se uma alternativa promissora para a produção das chamadas embalagens ativas, que promovem a segurança alimentar a partir da ação antimicrobiana. Sendo assim, o objetivo deste trabalho foi produzir filmes de PLA por casting aditivados com óleos essenciais (OE) de cravo, laranja e canela, para sua possível aplicação como embalagem ativa. Os óleos foram caracterizados por Cromatografia Gasosa acoplada com Espectrômetro de Massa (GC-MS), Espectroscopia no infravermelho com transformada de Fourier (FTIR) e por disco-difusão em ágar. Os filmes foram caracterizados por Microscopia óptica (MO), Calorimetria Exploratória Diferencial (DSC), FTIR, Análise Termogravimétrica (TG) e Análise antimicrobiana do filme. Com os resultados obtidos foi possível observar que o filme de PLA com os óleos essenciais apresentaram melhora no desempenho quanto a sua propriedade térmica e atividade antimicrobiana. Dentre os três filmes aditivados, o filme PLA/OE Cravo destacou-se por haver uma intensa ação bactericida sem degradação do filme, o que o torna um promissor aditivo adicionado ao PLA para aplicações em indústrias de embalagens.

Porosity of CHA Zeolite Driving the Formation of Polyaromatic Coke Species in the Methanol to Olefins Reaction

The pore size of the chabazite structure is exceptionally suitable for the methanol to olefins (MTO) reaction. The reaction has an induction period required for the formation of a hydrocarbon pool (HP), usually composed of aromatic compounds of different sizes. HP is alkylated by methanol and afterward cracked, leading to the formation of olefins. Despite the importance of HP, its formation and growth in size are exceedingly dependent on the porosity of the catalyst. The ideal is that the formed HP remains stable throughout the reaction because the growth in its size causes blockage of the small catalyst pores, decreasing its capacity. Herein we studied chabazite zeolites with different porosity and structure, caused by variation in the particle size and pores’ volume. Porosity influenced the formation of HP species in quantity (as revealed by thermogravimetric analysis (TGA)) and polymerization degree (gas chromatography coupled with mass spectrometer (GC-MS) analysis) and, consequently, the MTO reaction’s performance.

CHEMICAL AND THERMOANALYTICAL CHARACTERIZATION OF THE PINK PEPPER (Schinus terebinthifolius Raddi) SEEDS ESSENTIAL OIL

The essential oil (EO) of pink pepper has important biological properties that can enhance its application in the pharmaceutical, cosmetic and food industries. The objective of this study was to characterize the EO of pink pepper seeds in terms of their chemical composition and thermophysical properties. Certified pink pepper seeds obtained commercially were used. The EO was extracted by hydrodistillation and chemically characterized in a gas chromatograph coupled to mass spectrometer (GC/MS). The thermoanalytical characterization was performed on a simultaneous high resolution equipment, and the Thermogravimetric Analysis (TG) and Differential Scanning Calorimetry (DSC) were used to determine the physical-chemical and kinetic properties of the OE in the room temperature range up to 250 ºC in the 20 ºC.min-1 ratio under nitrogen atmosphere. The Arrhenius kinetic model was applied to determine the activation energy of the EO. A total of 51 chemical compounds were detected in the pink pepper EO, of which 42 compounds were identified (54.7% of monoterpene compounds and 45.3% sesquiterpenes). The major components were ?-pinene (26.80%), germacrene D (11.25%), sabinene (11.13%) and terpinen-4-ol (8.59%). The thermogravimetric analysis indicated a single stage of thermo-degradation of the pink pepper EO between 74.8 ºC and 184.7 ºC, being an endothermic peak in the physical transition of vaporization. The variation of enthalpy and activation energy of EO were found with values of = - (39.8 ± 9.5) KJ.Kg-1 and = - (2,546 ± 0.033) KJ.mol-1, respectively. The data presented in the thermogravimetric analysis of pink pepper seeds EO allowed observing important thermal parameters for the definition of industrial processes that can use it as raw material, so that its biological activities can remain stable under controlled temperature conditions and below the range degradation.

Proximal chemical evaluation and fatty acid in the chicatana ant and jumile

In the state of Tlaxcala, Mexico, the chicatana ant (Atta mexicana) and jumile (Edessa spp.) are foods that the population regularly consumes and are alternative sources of nutrients. Therefore, this study aims to evaluate the proximal chemical composition (moisture, protein, lipids, ash and carbohydrates) and fatty acids (FA) in commercialised dehydrated chicatana ant and jumile using instrumental methods such as refractive index (RI) and gas chromatography coupled with mass spectrometer (GC-MS). Protein and lipids were predominant in chicatana ant and jumile (33.74% and 39.25%, and 32.00% and 39.00%, respectively). In insect oils, RI and GC-MS results demonstrated that chicatana ant oil contains a high saturated FA percentage (58.40%), with heneicosanoic acid (C21:0) being the predominant saturated FA (46.35%), while jumile oil presented a higher percentage of unsaturated acids (99.27%), with γ-linolenic acid being the predominant unsaturated FA (77.00%). Therefore, both insects are foods with important protein and FA percentage, with jumile containing a higher concentration of unsaturated FA, which is desirable in the diet.

Electrocatalytic Oxidation of Dibenzothiophene and 4,6-Dimethyldibenzothiophene at Gold-Polyaniline (Au-PANI) Composite Electrodes

In this study, glassy carbon electrodes modified with gold-polyaniline (Au-PANI) were evaluated for the ability to electrochemically oxidize dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT). Au-PANI was characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), transmission electron micrograph (TEM), and scanning electron micrograph (SEM). The role of nitrogen groups of PANI on the formation of Au-PANI was shown by FT-IR. XPS confirmed the various electronic states and environment of oxygen, nitrogen, gold, and carbon in Au-PANI film. TEM results indicated that Au particle size is in the range of 3.50–6.97 nm, while SEM results confirmed the heterogeneous nature of PANI and Au-PANI surfaces. In this study, density functional theory (DFT) with the B3LYP functional and 6-311++G** basis set was used to examine the electronic properties of DBT/4,6-DMDBT onto the surface of PANI nanocomposite. Electrochemical tests indicate that the Au-PANI exhibits high catalytic activity for DBT and 4,6-DMDBT electrooxidation. Oxidation products such as DBTO = dibenzothiophene sulfoxide; 4,6-DMDBTO = 4,6-dimethydibenzothiophene sulfoxide; DBTO2 = dibenzothiophene sulfone; and 4,6-DMDBTO2 = 4,6-dimethydibenzothiophene sulfone were confirmed by means of gas chromatograph coupled to mass spectrometer (GC-MS), 1H, and 13C NMR.

Proposal for a semi-quantitative method for the determination of volatile compounds in cocoa liquors

Seventy-four volatile compounds were identified and quantified from cocoa liquors of the ICS 95 and TCS 01 varieties produced in the department of Santander, Colombia. The compounds were extracted using the solid phase microextraction with head space (SPME-HS) technique, and identified by gas chromatography coupled to mass spectrometer (GC-MS) by comparing the mass spectra of each compound in the Wiley 275L library of mass spectra and the Kovats retention index (IK) ratio. A semi-quantitative method was proposed that included toluene as an internal standard to normalize the degree of recovery between samples and a response factor for each family, calculated using a compound characteristic of that functional group. The results associated with response factors for each family or group of compounds such as alcohols, acids, aldehydes, ketones, esters and pyrazines (2.19, 1.02, 2.84, 0.38, 6.38, 0.88 respectively) were different between families, however, there was no difference between compounds within the same family. The implemented method obtained a DOD and DML of 0.024 µg/kg and 0.037 µg/kg respectively and an accuracy expressed as percentage recovery (of characteristic compounds per family) of 96% on average. According to the precision of the method, the results show that the concentrations have an average coefficient of variation (%CV) of 7.38% assuring repeatability and good precision. Finally, for the analyzed and quantified samples, it was found that the compounds with higher concentration were acetic acid (42.633 mg/kg), 2-phenylethyl acetate (29.44 mg/kg), 2.3-butanediol (345.39 mg/kg), 2-phenylethanol (12.595mg/kg) and 2.3.5.6-tetramethylpyrazine (8.601 mg/kg).

Catalytic valorization of waste soap into hydrocarbon rich oil and fuel gas

The present work is focused on the development of an effective process for the conversion of waste soap into fuel oil and gas. The waste soap was converted into highly combustible gas and oil by using low-cost white cement and burnt brick powder catalysts. Optimum conditions for both catalytic and non-catalytic pyrolysis were investigated by varying temperature, weight of catalyst, and reaction duration. All the experiments were carried out in a custom-made furnace and stainless steel pyrolyzer. The gaseous product was identified as alkenes and alkynes during their chemical analysis. The presence of carbon monoxide in the gaseous product was assessed from the color of the flame while the presence of hydrogen was examined through the GC-MS analysis. The oil fraction was separated into gasoline and kerosene fractions using fractional distillation approach. The qualitative and quantitative analysis of the oil was carried out using gas chromatography coupled with mass spectrometer (GC-MS). The oil obtained at 600 °C by non-catalytic pyrolysis, white cement–catalyzed, and clinker–catalyzed pyrolysis presented hydrocarbon content of 13.27%, 70.70%, and 46.44%, respectively.

Schinus terebinthifolius essential oil and fractions in the control of Aedes aegypti

Several technologies have been developed to control Aedes aegypti, mainly studies on isolated plant molecules. The Schinus terebinthifolius (Raddi) (Anacardiaceae), popularly known as pink pepper is a plant widely used in reforestation of degraded areas and its fruits are used as condiments. The objective of this work was to investigate the potential of essential oils (EOs) and fractions (FRs) obtained from fresh fruits and leaves of S. terebinthifolius. The EOs were obtained by hydrodistillation (2 hours), fractionated on a chromatographic column using as the stationary phase silica gel 60 (0.063-0.2mm), mobile phases: n-hexane, dichloromethane, ethyl acetate and methanol and chemically evaluated by gas chromatography coupled to mass spectrometer (GC/MS). EOs and FRs were tested against larvae of the third stage and pupae of Ae. aegypti by Immersion Test at concentrations ranging from 500.00 to 0.003 mg mL-1 (v/v). The hexane FRs obtained from fruits and leaves were the ones that showed the greatest activity on the larvae (LC99.9= 0.60 mg mL-1 and LC99.9 0.64 mg mL-1, respectively) and pupae (LC99,9 = 2.51 mg mL-1 and 2.61 mg mL-1, respectively). These results were confirmed by the anticholinesterase activity where the hexane (fruit and leaf) FRs presented the highest inhibitory potential on the acetylcholinesterase enzyme (0.156 mg mL-1 and 0.312 mg mL-1, respectively), suggesting the likely mechanism of action. The larvicidal potential can be explained by the presence of the major compounds bicyclogermacrene and germacrene D in the hexane FRs, indicating in this way that they may replace or even act in synergisms with conventional chemical larvicides. In this way the present study opens the field for new researches, aiming the development of products with the compounds bicyclogermacrene and germacrene D, as an alternative in the control of this culicide.