Separation and quantification of diazinon in water samples using liquid-phase microextraction-based effervescent tablet-assisted switchable solvent method coupled to gas chromatography-flame ionization detection.

This study used a liquid-phase microextraction-based effervescent tablet-assisted switchable solvent method coupled to gas chromatography-flame ionization detection as an eco-efficient, convenient-to-use, cost-effective, sensitive, rapid, and efficient method for extracting, preconcentrating, and quantifying trace amounts of diazinon in river water samples. As a switchable solvent, triethylamine (TEA) was used. In situ generation of CO2 using effervescent tablet containing Na2 CO3 and citric acid changed the hydrophobic TEA to the hydrophilic protonated triethylamine carbonate (P-TEA-C). CO2 removal from the specimen solution using NaOH caused P-TEA-C to be converted into TEA and led to phase separation, during which diazinon was extracted into the TEA phase. The salting-out process was helpful in enhancing extraction efficiency. In addition, a number of significant parameters that affect extraction recovery were examined. Under optimum conditions, the limit of detection and limit of quantitation were 0.06 and 0.2 ng/ml, respectively. The extraction recovery percentage and pre-concentration factor were obtained at 95 and 190%, respectively, and the precision (inter- and intra-day, relative standard deviation %, n = 5) was <5%.

Endogenous n-Alkanes in Vegetable Oils: Validation of a Rapid Offline SPE-GC-FID Method, Comparison with Online LC-GC-FID and Potential for Olive Oil Quality Control.

The potential of endogenous n-alkane profiling for the assessment of extra virgin olive oils (EVOO) adulteration (blends with cheaper vegetable oils) has been studied by relatively few authors. Analytical methods used for this purpose often involve tedious and solvent-intensive sample preparation prior to analytical determination, making them unattractive. A rapid and solvent-sparing offline solid phase extraction (SPE) gas chromatography (GC) flame ionization detection (FID) method for the determination of endogenous n-alkanes in vegetable oils was, therefore, optimized and validated. The optimized method demonstrated good performance characteristics in terms of linearity (R2 > 0.999), recovery (on average 94%), and repeatability (residual standard deviation, RSD < 11.9%). The results were comparable to those obtained with online high-performance liquid chromatography (HPLC)-GC- FID ( RSD < 5.1%). As an example of an application to prove the potentiality of endogenous n-alkanes in revealing frauds, the data set obtained from 16 EVOO, 9 avocado oils (AVO), and 13 sunflower oils (SFO), purchased from the market, was subjected to statistical analysis and principal component analysis. Two powerful indices, namely (n-C29 + n-C31)/(n-C25 + n-C26) and n-C29/n-C25, were found to reveal the addition of 2% SFO in EVOO and 5% AVO in EVOO, respectively. Further studies are needed to confirm the validity of these promising indices.

Assessment of gas chromatography methodology approach for the trace evaluation of carcinogenic impurity, methyl chloride, in trimetazidine dihydrochloride.

OBJECTIVE: A simple and robust head space/gas chromatography with flame ionisation sensor (HS/GC/FIS) approach for the trace evaluation of carcinogenic impurity, methyl chloride, in trimetazidine dihydrochloride (TRD) drug ingredient and its formulation is described. METHOD: This HS/GC/FIS approach was based on separation and analysis of CH3Cl content on DB-624 [75.0m - length, 0.53mm - internal diameter, 3.0µm - film thickness] column using nitrogen as carrier gas flowing through the column at 3mL/min stream rate. Detection of eluted CH3Cl was accomplished with flame ionization sensor at a set temperature of 260̊C. RESULTS: The optimised HS/GC/FIS methodological approach was thoroughly validated, demonstrating that it was linear with range of 5.0ppm to 1508.4ppm, sensitive with detection limit of 1.65ppm and quantification limit of 5.01ppm, reproducible with RSD values of 2.10-2.35%, accurate with recoveries of 81.9-99.0%, robust with percent variation of 7.5-12.22% with respect to changes in oven temperature, injector temperature, detector temperature and practical for regular TRD quality control. CONCLUSION: The findings revealed that with this optimised HS/GC/FIS methodological approach, the trace amounts of carcinogenic impurity (methyl chloride) in TRD drug ingredient and formulation could be successfully measured.

Group-type quantitative analysis of flavor compounds in ripening avocados.

Avocados are a superfood gaining popularity in people's diet. Profiling and quantifying the volatiles associated with flavor can further help in understanding the fruit. However, this is challenging due to relatively low abundance of volatile compounds. The complex mixtures inherent to avocado flavor can result in coelutions using classical chromatographic techniques. To overcome these challenges, solid-phase microextraction was used to extract and preconcentrate volatiles, then separated and quantified using two-dimensional gas chromatography with a flame ionization detector. This technique enhances separation power and produces well-ordered chromatograms, allowing for templated groupings of compounds of similar chemical composition into regions. Using the flame ionization detector, an average response factor was determined and used for quantification of these templated group-type regions, as well as individual compounds. This group-type quantification improved the overall precision of compound classes in 50 avocados by at least a factor of 2, when compared to that of the individual components. Overall, the abundance of associated flavor groups, such as terpenes and alcohols decreased, whereas aldehyde groups remained constant throughout ripening. The combination of solid-phase microextraction with two-dimensional gas chromatography and group-type quantification allows for an overall better understanding of the volatiles associated with flavor of avocados.

Simultaneous determination of trace level riot control agents in environmental water by solid-phase microextraction and gas chromatography coupled with a flame ionization detector.

In this paper, a direct immersion solid-phase microextraction procedure for the simultaneous analyses of four primary riot control agents: 2-chloroacetophenone, o-chlorobenzylidene malonitrile, dibenz(b,f)-1,4-oxazepine, and oleoresin capsicum at µg/L concentration from environmental water was developed. Several parameters that influence the extraction effectiveness were investigated, including fiber type, extraction temperature, extraction time, starring rate, and salinity. Under the recommended conditions, the optimized method had reasonable linearity and accuracy. The average recovery of this method ranged from 84 to 108.1%. The limit of detection for all the analytes ranged from 0.2 to 3 µg/L and the limit of quantification ranged from 1 to 10 µg/L, respectively. A relative standard deviation from 3.0 to 4.3% can be achieved depending on the compounds. The procedure was applied to analyze all the four riot control agents simultaneously in several environmental samples.

Development of effervescence-assisted switchable polarity solvent homogeneous liquid-phase microextraction for the determination of permethrin and deltamethrin in water samples prior to gas chromatography-flame ionization detection.

An effervescent tablet-assisted switchable polarity solvent-based homogeneous liquid-phase microextraction combined with gas chromatography with flame ionization detection has been conducted for the separation, preconcentration, and detection of permethrin and deltamethrin in the river water specimens. Triethylamine (TEA) was utilized as the switchable polarity solvent in this method. The switching process was carried out by the dissolution of an effervescent tablet including an effervescency agent (sodium carbonate) and a proton donor agent (citric acid). Changing the pH of the specimen solution enhanced the conversion of TEA into protonated triethylamine carbonate through the tablet that generated carbon dioxide bubbles in situ. Finally, the addition of sodium hydroxide changed the ionization state of TEA and separated the two phases. Influential factors in the extraction were investigated. According to optimal situations, the limit of detection and the limit of quantification were 0.16 and 0.5 µg L-1 for permethrin and 0.03 and 0.1 µg L-1 for deltamethrin, respectively. The preconcentration factor was 194 in river water samples and inter- and intra-day precision (relative standard deviation %; n = 5) was <5%. The extraction recovery was obtained in the range of 93.0%-97% for permethrin and deltamethrin in water samples.

Investigation of a Complex Reaction Pathway Network of Isobutane/2-Butene Alkylation by CGC-FID and CGC-MS-DS.

The mechanism of reaction in isobutane/2-butene alkylation systems is extremely complicated, accompanied by numerous side reactions. Therefore, a comprehensive understanding of the reaction pathways in this system is essential for an in-depth discussion of the reaction mechanism and for improving the selectivity of the major products (clean fuel blend components). The alkylation of isobutane/2-butene was studied using a self-made intermittent reaction device with a metering, cooling, reaction, vacuum and analysis system. The alkylates were qualitatively and quantitatively analyzed using a capillary gas chromatography-mass spectrometry-data system (CGC-MS-DS) and capillary gas chromatography with flame ionization detection (CCGC-FID), respectively, and the precision and recovery of the quantitative analytical methods were verified. The results showed that the relative standard deviation (RSD) of the standard sample was below 0.78%, and the recoveries were from 98.53% to 102.85%. Under the specified reaction conditions, 79 volatile substances were identified from the alkylates, and the selectivity of C8 and trimethylpentanes (TMPs) reached 63.63% and 53.81%, respectively. The changes of the main chemical components in the alkylation reaction with time were tracked and analyzed, based on which reaction pathways were determined, and a complex reaction network containing the main products' and the by-products' generation pathway was constructed.

Low-Cost Detection of Methane Gas in Rice Cultivation by Gas Chromatography-Flame Ionization Detector Based on Manual Injection and Split Pattern.

Rice cultivation is one of the most significant human-created sources of methane gas. How to accurately measure the methane concentration produced by rice cultivation has become a major problem. The price of the automatic gas sampler used as a national standard for methane detection (HJ 38-2017) is higher than that of gas chromatography, which greatly increases the difficulty of methane detection in the laboratory. This study established a novel methane detection method based on manual injection and split pattern by changing the parameters of the national standard method without adding any additional automatic gas samplers. The standard curve and correlation coefficient obtained from the parallel determination of methane standard gas were y = 2.4192x + 0.1294 and 0.9998, respectively. Relative standard deviation (RSD, <2.82%), recycle rate (99.67−102.02%), limit of detection (LOD, 0.0567 ppm) and limit of quantification (LOQ, 0.189 ppm) of this manual injection method are satisfying, demonstrating that a gas chromatography-flame ionization detector (GC-FID), based on manual injection at a split ratio (SR) of 5:1, could be an effective and accurate method for methane detection. Methane gases produced by three kinds of low-methane rice treated with oxantel pamoate acid, fumaric acid and alcohol, were also collected and detected using the proposed manual injection approach Good peak shapes were obtained, indicating that this approach could also be used for quantification of methane concentration.

Development of a Gas-Tight Syringe Headspace GC-FID Method for the Detection of Ethanol, and a Description of the Legal and Practical Framework for Its Analysis, in Samples of English and Welsh Motorists' Blood and Urine.

Ethanol is the most commonly used recreational drug worldwide. This study describes the development and validation of a headspace gas chromatography flame ionisation detection (HS-GC-FID) method using dual columns and detectors for simultaneous separation and quantitation. The use of a dual-column, dual-detector HS-GC-FID to quantitate ethanol is a common analytical technique in forensic toxicology; however, most analytical systems utilise pressure-balance injection rather than a simplified gas-tight syringe, as per this technique. This study is the first to develop and validate a technique that meets the specifications of the United Kingdom's requirements for road traffic toxicology testing using a Shimadzu GC-2014 gas-tight syringe. The calibration ranged from 10 to 400 mg/100 mL, with a target minimum linearity of r2 > 0.999, using tertiary butanol as the internal standard marker. The method has an expanded uncertainty at 99.73% confidence of 3.64% at 80 mg/100 mL, which is the blood alcohol limit for drink driving in England and Wales. In addition, at 200 mg%­the limit at which a custodial sentence may be imposed on the defendant­the expanded uncertainty was 1.95%. For both the 80 mg% and 200 mg% concentrations, no bias was present in the analytical method. This method displays sufficient separation for other alcohols, such as methanol, isopropanol, acetaldehyde, and acetone. The validation of this technique complies with the recommended laboratory guidelines set out by United Kingdom and Ireland Association of Forensic Toxicologists (UKIAFT), the recently issued Laboratory 51 guidelines by the United Kingdom Accreditation Service (UKAS), and the criteria set out by the California Code of Regulations (CCR), 17 CCR § 1220.1.

Comparative Investigation of Conventional and Innovative Headspace Extraction Methods to Explore the Volatile Content of Human Milk.

The odor of human milk induces search-like movements and oral activation in newborns, which increases their chances of taking advantage of milk intake and benefits. However, the underlying volatile fraction of human milk remains understudied. This study aimed to devise a simple method to extract a wide range of volatile compounds from small-volume human milk samples. Headspace solid phase micro-extraction (HS-SPME) with a Car/PDMS fiber and dynamic headspace extraction (D-HS) with a Tenax or a trilayer sorbent were tested because of their selective affinity for volatiles. Then, innovative variations of these methods were developed to combine their respective advantages in a one-step extraction: Static headspace with multiple SPME fibers (S-HS-MultiSPME), Dynamic headspace with multiple SPME fibers (D-HS-MultiSPME) and dynamic headspace with multiple SPME fibers and Tenax (D-HS-MultiSPME/Tenax). The extracts were analyzed by gas chromatography coupled with mass spectrometric and flame ionization detection. The relative performances of these methods were compared based on qualitative and semi-quantitative analyses of the chromatograms. The D-HS technique showed good sensitivity for most compounds, whereas HS-SPME favored the extraction of acids. The D-HS-MultiSPME/Tenax identified more than 60 compounds from human milk (some for the first time) and evidence of individual singularities. This method that can be applied to volatilome analysis of any biological fluid should further our understanding of human milk odor.

Fatty Acids of Ten Commonly Consumed Pulses.

Gas chromatography (GC) with flame ionization detection (FID) and mass spectrometry (MS) detection were used to characterize the fatty acid (FA) compositions of ten commonly consumed (i.e., market class) pulses. Lipids from ground pulses were extracted using a classical chloroform/methanol extraction and quantified by GC-FID with structural confirmation by GC-MS. Principal component analysis (PCA) was applied to FA compositions of the pulse extracts, and the pulses clustered into three distinct groups: one rich in linolenic acid, 18:3 (carbon number:unsaturation, C:U), one rich in 16:0, and one in which 18:1 was highest, along with predominant 18:2. These ten pulses averaged 46.1% linoleic acid (18:2), 22.7% oleic acid (18:1), 18.0% palmitic acid (16:0), and 7.6% linolenic acid (18:3). Individual values ranged widely, with 18:2 ranging from 26.0% in black beans to 48.4% in garbanzo beans. The greatest difference was in 18:3, which ranged from 2.2% in garbanzo beans to 38.8% in pinto beans. Oxo-FA were observed in all ten samples, and the distribution of oxo-FA in the samples also varied. Overall, the very different FA compositions of pulses lead to the possibility of breeding and genetic modification between pulses to produce the most desirable FA composition for nutritional benefit.

High-Performance NMHC Detection Enabled by a Perylene Bisimide-Cored Metallacycle Complex-Based Fluorescent Film Sensor.

Non-methane hydrocarbons (NMHCs) can serve as precursors of ozone and photochemical smog, and hence their highly efficient detection is of great importance for air quality monitoring. Here, we synthesized a new fluorescent perylene bisimide (PBI)-cored metallacycle complex through coordination-driven self-assembly and used it for the production of a fluorescent film sensor. The unique rectangular structure of the developed fluorophore endows the sensor with enhanced sensing performance and discriminability to n-alkanes (C5-10). Specifically, the experimental detection limits for n-pentane, n-hexane, and n-decane are 39, 7, and 1.4 mg/m3, respectively, and the corresponding linear ranges are from 39 to 2546, 7 to 1745, and 1.4 to 85 mg/m3, respectively. Moreover, the sensing is fully reversible. In tandem with a gas chromatographic separation system, the film sensor showed comparable detection ability for the n-alkanes with a commercial flame ionization detector (FID), while the film sensor needs no hydrogen; it occupies a much smaller size (30 × 30 × 44 mm3) and consumes less energy (0.215 W). Further studies demonstrated that the developed sensor can be used for on-site and real-time quantification of NHMCs, laying the foundation for developing into a portable detector.

A simplified method for the quantitation of short-chain fatty acids in human stool.

A one-vial extraction method for the quantitation of short-chain fatty acids (SCFAs) in human stool was developed. Samples were extracted with an acidified aqueous internal standard solution, sodium sulfate, and diethyl ether, followed by analysis with GC-FID. Accuracy, in terms of relative recovery, was typically between 90 and 110% for most analytes; without internal standard, the accuracy was about 5-34%; the linear dynamic range (LDR) was 0.05-50 µmol per gram; the limit of detection (LOD) was less than or equal to 0.05 µmol per gram; and the (lower) limit of quantitation (LOQ) was 1 µmol per gram. The method is suitable for quantitating acetic acid, propanoic acid, isobutyric acid, butyric acid, isovaleric acid, valeric acid, isohexanoic acid, hexanoic acid, and heptanoic acid. It is not suitable for the quantitation of formic acid. Application to human biological research was tested by the measurement of SCFA in heathy humans. This confirmed that the method performed adequately, and even better than expected, with values up to 150 µmol per gram.

Evidence for cometabolic transformation of weathered toxaphene under aerobic conditions using camphor as a co-substrate.

AIMS: Toxaphene is a persistent organic pollutant, composed of approximately 1000 highly chlorinated bicyclic terpenes. The purpose of this study was to evaluate if camphor, a structural analogue of toxaphene, could stimulate aerobic biotransformation of weathered toxaphene. METHODS AND RESULTS: Two enrichment cultures that degrade camphor as the sole carbon source were established from contaminated soil and biosolids. These cultures were used to evaluate aerobic transformation of weathered toxaphene. Only the biosolids culture could transform compounds of technical toxaphene (CTTs) in the presence of camphor, while no transformation was observed in the presence of glucose or with toxaphene as a sole carbon source. The transformed toxaphene had lower concentration of CTTs with longer retention times, and higher concentration of compounds with lower retention times. Gas chromatography with electron capture negative ion mass spectrometry (GC/ECNI-MS) showed that aerobic biotransformation mainly occurred with Cl8 - and Cl9 -CTTs compounds. The patterns of Cl6 - and Cl7 -CTTs were also simplified albeit to a much lesser extent. Seven camphor-degrading bacteria were isolated from the enrichment culture but none of them could degrade toxaphene. CONCLUSION: Camphor degrading culture can aerobically transform CCTs via reductive pathway probably by co-metabolism using camphor as a co-substrate. SIGNIFICANCE AND IMPACT OF THE STUDY: Since camphor is naturally produced by different plants, this study suggests that stimulation of aerobic transformation of toxaphene may occur in nature. Moreover plants, which produce camphor or similar compounds, might be used in bioremediation of contaminated soils.

Development and validation of a gas chromatography method coupled with flame ionization detector for quantitative analysis of fragrance allergens in aromas for e-cigarettes.

Aromas can give smell and/or flavor to a variety of products in the cosmetic and food industry. They are also used as e-cigarette additives. Some of those substances are recognized as fragrance allergens and can cause allergic reactions so there is a need to control their use. Gas chromatography is the method of choice for analyzing fragrance allergens because of their low boiling points. This study aimed to develop and validate a robust and simple method for the analysis of fragrance allergens in aromas for e-cigarettes. A method using gas chromatography coupled with a flame ionization detector was developed for 25 fragrance allergens. Optimized parameters were sample diluent, internal standard, and carrier gas. The output method was the one previously developed and optimized. The linearity of the method was >0.994 over the range of 0.5-40 µg/mL. Accuracy and precision were within the acceptance range. Limits of detection and quantification were determined, and calibration curves were plotted. The method was applied to three real samples of aromas. Thirteen fragrance allergens were detected. Concentrations varied in the range of dozens to thousands of µg/mL showed that concentrations of fragrances in aromas for e-cigarettes can be high and varies among products.

The effect of Haemonchus contortus and Trichostrongylus colubriforms infection on the ruminal microbiome of lambs.

We evaluated Haemonchus contortus (HC) and Trichostrongylus colubriformis (TC) infection on the ruminal microbial community of Santa Ines lambs to better understand the pathophysiology of parasite infections and the interactions among gastrointestinal nematodes and gut resident microbiota. In this study, 18 six months of age lambs were maintained for 34 days in individual pens divided into three treatments that included animals infected with HC and TC, and control (infection-free). Haematological, ruminal parameter and microbial nitrogen absorbed by pune derivatives, as well as enteric methane emission (CH4), were analysed, and the rumen microbial taxonomic and functional profile assessed by shotgun metagenomics. The analysis showed that total protein, albumin, urea, and butyrate level were lower in animals infected by both parasites, while HC infection also decreased the haemoglobin level. Both infected groups (TC and HC) increased the enteric methane emission (CH4). TC and HC infections increased the diversity and richness of functional microbial genes. Most alterations in the rumen microbiome composition of infected groups are associated with the suppression of microbes involved in microbial homeostasis maintenance and expansion of the archaeal community in the infected animals. Infection led to an increased abundance of nitrogen, amino acid, protein, and energy metabolism genes. Overall, TC and HC infection increased the enteric methane emission, negatively affected taxon's responsible for maintenance de rumen homeostasis and modulated some important genes related to protein and energy metabolism.

Bioactive Triterpenes of Protium heptaphyllum Gum Resin Extract Display Cholesterol-Lowering Potential.

Hypercholesterolemia is one of the major causes of cardiovascular disease, the risk of which is further increased if other forms of dyslipidemia occur. Current therapeutic strategies include changes in lifestyle coupled with drug administration. Statins represent the most common therapeutic approach, but they may be insufficient due to the onset of resistance mechanisms and side effects. Consequently, patients with mild hypercholesterolemia prefer the use of food supplements since these are perceived to be safer. Here, we investigate the phytochemical profile and cholesterol-lowering potential of Protium heptaphyllum gum resin extract (PHE). Chemical characterization via HPLC-APCI-HRMS2 and GC-FID/MS identified 13 compounds mainly belonging to ursane, oleanane, and tirucallane groups. Studies on human hepatocytes have revealed how PHE is able to reduce cholesterol production and regulate the expression of proteins involved in its metabolism. (HMGCR, PCSK9, LDLR, FXR, IDOL, and PPAR). Moreover, measuring the inhibitory activity of PHE against HMGR, moderate inhibition was recorded. Finally, molecular docking studies identified acidic tetra- and pentacyclic triterpenoids as the main compounds responsible for this action. In conclusion, our study demonstrates how PHE may be a useful alternative to contrast hypercholesterolemia, highlighting its potential as a sustainable multitarget natural extract for the nutraceutical industry that is rapidly gaining acceptance as a source of health-promoting compounds.

Method Development and Validation for Omega-3 Fatty Acids (DHA and EPA) in Fish Using Gas Chromatography with Flame Ionization Detection (GC-FID).

Gas chromatography with flame ionization detection (GC-FID) has often been used to quantify fatty acids in fish. This study validated the common method for determining omega-3 fatty acids (DHA and EPA) in the raw and cooked warm-water fish, selayang, using GC-FID for subsequent evaluation on EPA and DHA retention using the Weibull model. The EPA and DHA were separated using a high-polarity capillary GC HP-88 column (60 m length, 0.25 mm ID, 0.2 µm DF) with a total run time of 45.87 min. The method was validated in linearity, precision, accuracy, specificity and sensitivity based on ICH requirements. In addition, it was found that the method had a high recovery rate (>95%) and good precision (RSD ≤ 2%) with overall RSDs ranging below 0.001% for both omega-3 PUFA. In conclusion, this method identified and quantified fatty acids and omega-3 accurately and precisely and can be used effectively for routine FAME analysis in fish samples.

Using Design of Experiments to Optimize a Screening Analytical Methodology Based on Solid-Phase Microextraction/Gas Chromatography for the Determination of Volatile Methylsiloxanes in Water.

Volatile methylsiloxanes (VMSs) constitute a group of compounds used in a great variety of products, particularly personal care products. Due to their massive use, they are continually discharged into wastewater treatment plants and are increasingly being detected in wastewater and in the environment at low concentrations. The aim of this work was to develop and validate a fast and reliable methodology to screen seven VMSs in water samples, by headspace solid-phase microextraction (HS-SPME) followed by gas chromatography with flame ionization detection (GC-FID). The influence of several factors affecting the extraction efficiency was investigated using a design of experiments approach. The main factors were selected (fiber type, sample volume, ionic strength, extraction and desorption time, extraction and desorption temperature) and optimized, employing a central composite design. The optimal conditions were: 65 µm PDMS/Divinylbenzene fiber, 10 mL sample, 19.5% NaCl, 39 min extraction time, 10 min desorption time, and 33 °C and 240 °C as extraction and desorption temperature, respectively. The methodology was successfully validated, showing low detection limits (up to 24 ng/L), good precision (relative standard deviations below 15%), and accuracy ranging from 62% to 104% in wastewater, tap, and river water samples.

Soil and Leaf Nutrients Drivers on the Chemical Composition of the Essential Oil of Siparuna muricata (Ruiz & Pav.) A. DC. from Ecuador.

Chemical compositions of plants are affected by the initial nutrient contents in the soil and climatic conditions; thus, we analyzed for the first time the effects of soil and leaf nutrients on the compositions of the essential oils (EOs) of Siparuna muricata in four different localities in Ecuador. EOs were obtained by hydrodistillation and analyzed by gas chromatography/mass spectrometry (GC/MS) and a gas chromatography/flame ionization detector (GC/FID). Enantiomeric distribution by GC/MS was determined, modifying the enantiomeric separation of ß-pinene, limonene, δ-elemene, ß-bourbonene, cis-cadina-1 (6), 4-diene and atractylone. A total of 44 compounds were identified. The most representative for L1 were guaiol, atractylone and 4-diene; for L2, cis-cadina-1(6),4-diene and myrcene; for L3, atractylone, myrcene and germacrene B; and finally, L4 germacrene B, myrcene and cis-cadina-1(6),4-diene. Correlations between soil- leaf chemical elements such as Al, Ca, Fe, Mg, Mn, N and Si in the different localities were significant with chemical composition of the essential oil of Siparuna muricata; however, correlations between soil and leaf K, P, and Na were not significant. Cluster and NMDS analysis showed high dissimilarity values of secondary metabolites between four localities related with changes in soil- leaf nutrients. Thus, the SIMPER routine revealed that not all secondary metabolites contribute equally to establishing the differences in the four localities, and the largest contributions are due to differences in guaiol, cis-cadina-1(6),4-diene, atractylone and germacrene. Our investigation showed for the first time the influences of altitude and soil- leaf chemical elements in the chemical composition of the EOs of S. muricata.