RESUMO
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.
Assuntos
Alcanos , Óleos de Plantas , Azeite de Oliva/química , Óleos de Plantas/química , Ionização de Chama/métodos , Cromatografia Gasosa/métodos , Óleo de Girassol , Solventes/análise , Extração em Fase Sólida/métodosRESUMO
The chemical composition and biological activities of the essential oils from the leaves, stems, and roots of Kadsura coccinea (K. coccinea) were investigated. The essential oils were extracted by hydro distillation and analyzed by gas chromatography mass spectrometry (GC-MS) and gas chromatography with flame ionization detector (GC-FID). Antioxidant activities of the essential oils were examined with DPPH radical scavenging assay, ABTS cation radical scavenging assay, and ferric reducing antioxidant power assay. Antimicrobial activities were evaluated by determining minimum inhibitory concentrations (MIC) and minimum microbiocidal concentrations (MMC). Acetylcholinesterase and butyrylcholinesterase inhibitory activity of the essential oils were also tested. A total of 46, 44, and 47 components were identified in the leaf, stem, and root oils, representing 95.66%, 97.35%, and 92.72% of total composition, respectively. The major compounds of three essential oils were α-pinene (16.60-42.02%), ß-pinene (10.03-18.82%), camphene (1.56-10.95%), borneol (0.50-7.71%), δ-cadinene (1.52-7.06%), and ß-elemene (1.86-4.45%). The essential oils were found to have weak antioxidant activities and cholinesterase inhibition activities. The essential oils showed more inhibitory effects against Staphylococcus aureus (S. aureus) than those of other strains. The highest antimicrobial activity was observed in the root oil against S. aureus, with MIC of 0.78 mg/mL. Therefore, K. coccinea essential oils might be considered as a natural antibacterial agent against S. aureus with potential application in food and pharmaceutical industries.
Assuntos
Kadsura/química , Óleos Voláteis/análise , Óleos Voláteis/química , Folhas de Planta/química , Raízes de Plantas/química , Caules de Planta/química , Acetilcolinesterase/química , Antibacterianos/química , Antibacterianos/farmacologia , Antioxidantes/química , Antioxidantes/farmacologia , Monoterpenos Bicíclicos/química , Monoterpenos Bicíclicos/farmacologia , Butirilcolinesterase/química , Butirilcolinesterase/farmacologia , Ionização de Chama/métodos , Testes de Sensibilidade Microbiana/métodos , Óleos Voláteis/farmacologia , Óleos de Plantas/análise , Óleos de Plantas/química , Óleos de Plantas/farmacologia , Sesquiterpenos/química , Staphylococcus aureus/efeitos dos fármacosRESUMO
Potato (Solanum tuberosum L.) tubers are usually harvested once a year; thus, long-term storage is required to supply quality-assured tubers throughout the year. Further, an applicable method to predict tuber quality during storage is needed. In this study, gas chromatography-mass spectrometry (GC/MS) metabolomics was applied to identify applicable biomarkers for prediction of potato chip color based on 3 years' field-grown tubers. The projections to latent structures (PLS) prediction model, calculated from a metabolome data set obtained before storage, was consistent with actual measured chip color values. Additionally, GC with frame ionization detector (GC/FID) metabolite fingerprinting simultaneously re-constructed more reliable and relevant prediction models for chip color quality compared to GC/MS. Moreover, nine metabolites detected by GC/MS analysis were further validated as applicable prediction markers. This strategy will provide a practical and cost-effective quality-control tool for potato processing manufacturers on an industrial scale.
Assuntos
Ionização de Chama/métodos , Qualidade dos Alimentos , Cromatografia Gasosa-Espectrometria de Massas , Metabolômica , Tubérculos/metabolismo , Solanum tuberosum/metabolismo , Biomarcadores/metabolismo , CorRESUMO
Triacyl-, diacyl- and monoacylglycerols (TAGs, DAGs, MAGs) along with monocarboxylic acids (MCAs) are intermediate products in many triacylglycerol oil-to-biofuel conversion pathways. Accumulation of these compounds leads to poor biofuel characteristics and may result in fuel system damage. We developed a method for simultaneous identification and quantification of a wide range of MCAs (C4-C18), MAGs, DAGs, and TAGs. The method is based on trimethylsilylation followed by high temperature GC with programmed temperature vaporizer (PTV) injection coupled to parallel FID and MS detectors (HTGC-FID/MS). To minimize the discrimination of both low and high molecular weight species typically occurring on the injector, we optimized injection conditions using a central composite design. The critical variables were the time at initial temperature (40 °C), splitless time, and the interaction between these two parameters. Among three tested electron ionization source/quadrupole analyzer temperatures, a 350/200 °C setting provided the highest response and signal-to-noise ratio for TAGs and did not have an effect on MAGs and DAGs. Similar results were obtained when quantifying target analytes in intermediate products of soybean oil cracking with FID and MS (using specific acylglycerol fragmentation ions). The instrumental FID limits of detection (LODs) were 0.07-0.27 ng for most of the target analytes. Selected ion monitoring (SIM) LODs were 0.01-0.05 ng for MCAs and 0.03-0.14 ng for acylglycerols. For the total ion current (TIC), LODs observed increased with acyl chain length and degree of unsaturation, resulting in an increase from 0.05 to 0.18 ng for MCAs (C5 to C18) and from 0.03 to 1.8 ng for acylglycerols (TAGs C8 to C22). Deviations in the repeatability of sample preparation, intra- and inter-day analyses, including sample stability over an eight-day time period, did not exceed 10% variance. These results demonstrate that the developed method is accurate and robust for the determination of acylglycerols and MCAs produced during the processing of TAGs into biofuels.
Assuntos
Biocombustíveis/análise , Ácidos Carboxílicos/análise , Ionização de Chama/métodos , Cromatografia Gasosa-Espectrometria de Massas/métodos , Glicerídeos/análise , Temperatura Alta , Limite de Detecção , Óleo de Soja/químicaRESUMO
Background: Kombucha is a nonalcoholic, fermented tea beverage that has recently received negative attention because of documented concentrations of ethanol in excess of allowable limits of ≥0.5% alcohol by volume (ABV). Objective: Our previously reported headspace GC with flame-ionization detection (GC-FID) method was adopted by the AOAC Expert Review Panel as First Action Official MethodSM 2016.12 in September 2016 based on published single-laboratory validation study results. This paper describes the corresponding multilaboratory study using this method to further validate its performance parameters. Methods: Four laboratories participated in the study and received practice samples, test samples, reference standards, and detailed protocols. Eight kombucha samples sent out to laboratories were randomly assigned sample numbers and were blinded in terms of content and identity. Each laboratory analyzed all samples using the GC-FID method and reported their results. Results: Cochran's C-test and single and double Grubbs' tests were used to identify and remove outliers. Horwitz ratio values for all samples were between 0.5 and 1.7. As per the Standard Method Performance Requirements (SMPRs®), all samples within the analytical range of 0.1-2.0 ABV% had RSDR values <6%. Conclusions: The results from this study demonstrate the evaluated GC-FID method meets the SMPR requirements and is fit for purpose for detecting ethanol in kombucha products. Highlights: Kombucha, a nonalcoholic, fermented beverage, has been found to contain ≥0.5% ABV. First Action Official Method 2016.12, a headspace GC-FID method for determining ethanol in kombucha, is supported by a multilaboratory study.
Assuntos
Etanol/análise , Chá de Kombucha/análise , Ionização de Chama/métodosRESUMO
Dietary fatty acids can be both beneficial and detrimental to human health depending on the degree and type of saturation. Healthcare providers and research scientists monitor the fatty acid content of human plasma and serum as an indicator of health status and diet. In addition, both the Centers for Disease Control & Prevention (CDC) and the National Institutes of Health - Office of Dietary Supplements are interested in circulating fatty acids (FAs) because they may be predictive of coronary heart disease. The National Institute of Standards and Technology (NIST) provides a wide variety of reference materials (RMs) and Standard Reference Materials® (SRM®s) including blood, serum, plasma, and urine with values assigned for analytes of clinical interest. NIST SRM 2378 Fatty Acids in Frozen Human Serum was introduced in 2015 to help validate methods used for the analysis of FAs in serum, and consists of three different pools of serum acquired from (1) healthy donors who had taken fish oil dietary supplements (at least 1000 mg per day) for at least one month (level 1 material), (2) healthy donors who had taken flaxseed oil dietary supplements (at least 1000 mg per day) for at least one month (level 2 material), and (3) healthy donors eating "normal" diets who had not taken dietary supplements containing fish or plant oils (level 3 material). The use of dietary supplements by donors provided SRMs with natural endogenous ranges of FAs at concentrations observed in human populations. Results from analyses using two methods at NIST, including one involving a novel microwave-assisted acid hydrolysis procedure, and one at the CDC are presented here. These results and their respective uncertainties were combined to yield certified values with expanded uncertainties for 12 FAs and reference values with expanded uncertainties for an additional 18 FAs.
Assuntos
Cromatografia Gasosa/métodos , Suplementos Nutricionais , Ácidos Graxos/sangue , Ionização de Chama/métodos , Cromatografia Gasosa-Espectrometria de Massas/métodos , Preservação de Sangue , Cromatografia Gasosa/normas , Criopreservação , Suplementos Nutricionais/análise , Ácidos Graxos/normas , Ácidos Graxos Insaturados/sangue , Ácidos Graxos Insaturados/normas , Óleos de Peixe/administração & dosagem , Óleos de Peixe/sangue , Ionização de Chama/normas , Congelamento , Cromatografia Gasosa-Espectrometria de Massas/normas , Humanos , Óleos de Plantas/administração & dosagem , Óleos de Plantas/análise , Padrões de ReferênciaRESUMO
Recently, an increasing number of pharmacists had to supply medicinal products based on Cannabis sativa L. (Cannabaceae), prescribed by physicians to individual patients. Cannabis olive oil preparation is the first choice as a concentrated extract of cannabinoids, even though standardized operative conditions for obtaining it are still not available. In this work, the impact of temperature and extraction time on the concentration of active principles was studied to harmonize the different compounding methods, optimize the extraction process, and reduce the variability among preparations. Moreover, starting from the cannabis inflorescence, the effect of temperature on tetrahydrocannabinolic acid decarboxylation was evaluated. For the analysis, a GC/MS method, as suggested by the Italian Ministry of Health, and a GC/flame ionization detection method were developed, validated, and compared.
Assuntos
Canabinoides/análise , Cannabis/química , Azeite de Oliva/química , Extratos Vegetais/química , Cannabis/anatomia & histologia , Cannabis/ultraestrutura , Ionização de Chama/métodos , Cromatografia Gasosa-Espectrometria de Massas/métodos , Temperatura Alta , Microscopia , Microscopia Eletrônica de Varredura , Azeite de Oliva/uso terapêutico , Folhas de Planta/anatomia & histologia , Folhas de Planta/química , Folhas de Planta/ultraestruturaRESUMO
Cannabis (Cannabis sativa L.) is an annual herbaceous plant that belongs to the family Cannabaceae. Trans-Δ9-tetrahydrocannabinol (Δ9-THC) and cannabidiol (CBD) are the two major phytocannabinoids accounting for over 40% of the cannabis plant extracts, depending on the variety. At the University of Mississippi, different strains of C. sativa, with different concentration ratios of CBD and Δ9-THC, have been tissue cultured via micropropagation and cultivated. A GC-FID method has been developed and validated for the qualitative and quantitative analysis of acid and neutral cannabinoids in C. sativa extracts. The method involves trimethyl silyl derivatization of the extracts. These cannabinoids include tetrahydrocannabivarian, CBD, cannabichromene, trans-Δ8-tetrahydrocannabinol, Δ9-THC, cannabigerol, cannabinol, cannabidiolic acid, cannabigerolic acid, and Δ9-tetrahydrocannabinolic acid-A. The concentration-response relationship of the method indicated a linear relationship between the concentration and peak area ratio with R2 > 0.999 for all 10 cannabinoids. The precision and accuracy of the method were found to be ≤ 15% and ± 5%, respectively. The limit of detection range was 0.11â-â0.19 µg/mL, and the limit of quantitation was 0.34â-â0.56 µg/mL for all 10 cannabinoids. The developed method is simple, sensitive, reproducible, and suitable for the detection and quantitation of acidic and neutral cannabinoids in different extracts of cannabis varieties. The method was applied to the analysis of these cannabinoids in different parts of the micropropagated cannabis plants (buds, leaves, roots, and stems).
Assuntos
Canabinoides/análise , Cannabis/química , Ionização de Chama/métodos , Extratos Vegetais/química , Canabidiol/análise , Dronabinol/análiseRESUMO
An offline solid-phase extraction (SPE) approach combined with a large-volume injection (LVI)-gas chromatography-flame ionization detector (LVI-GC-FID) is improved for routine analysis of mineral oil saturated hydrocarbons (MOSH) in vegetable oils. The key procedure of the method consists in using offline SPE columns for MOSH purification. The SPE column packed with 1% Ag-activated silica gel was used to separate MOSH from triglycerides and olefins in variety of vegetable oils. The eluent of MOSH fraction was only 3 mL and the concentration step was quick with little evaporation loss. The limit of quantification (LOQ) of the method was 2.5 mg/kg and the linearity ranged from 2 to 300 mg/kg. The accuracy was assessed by measuring the recoveries from spiked oil samples and was higher than 90%. Twenty-seven commercial vegetable oils were analyzed, and different levels of MOSH contamination were detected with the highest being 259.4 mg/kg. The results suggested that it is necessary to routinely detect mineral oil contamination in vegetable oils for food safety.
Assuntos
Cromatografia Gasosa/métodos , Ionização de Chama/métodos , Contaminação de Alimentos/análise , Hidrocarbonetos/análise , Óleos Industriais/análise , Óleo Mineral/análise , Óleos de Plantas/química , Extração em Fase Sólida/métodos , Inocuidade dos AlimentosRESUMO
An improved method for on-line measurement of sulfur containing compounds in complex matrices is presented. The on-line system consists of a specifically designed sampling system connected to a comprehensive two-dimensional gas chromatograph (GC×GC) equipped with two capillary columns (Rtx®-1 PONA×SGE BPX50), a flame ionization detector (FID) and a sulfur chemiluminescence detector (SCD). The result is an unprecedented sensitivity down to ppm level (1 ppm-w) for various sulfur containing compounds in very complex hydrocarbon matrices. In addition to the GC×GC-SCD, the low molecular weight sulfur containing compounds such as hydrogen sulfide (H2S) and carbonyl sulfide (COS) can be analyzed using a thermal conductivity detector of a so-called refinery gas analyzer (RGA). The methodology was extensively tested on a continuous flow pilot plant for steam cracking, in which quantification of sulfur containing compounds in the reactor effluent was carried out using 3-chlorothiophene as internal standard. The GC×GC-FID/-SCD settings were optimized for ppm analysis of sulfur compounds in olefin-rich (ethylene- and propylene-rich) hydrocarbon matrices produced by steam cracking of petroleum feedstocks. Besides that is primarily used for analysis of the hydrocarbon matrix, FID of the GC×GC-FID/-SCD set-up serves to double check the amount of added sulfur internal standard which is crucial for a proper quantification of sulfur compounds. When vacuum gas oil containing 780 ppm-w of elemental sulfur in the form of benzothiophenes and dibenzothiophenes is subjected to steam cracking, the sulfur balance was closed, with 75% of the sulfur contained in the feed is converted to hydrogen sulfide, 13% to alkyl homologues of thiophene while the remaining 12% is present in the form of alkyl homologues of benzothiophenes. The methodology can be applied for many other conversion processes which use sulfur containing feeds such as hydrocracking, catalytic cracking, kerogen evolution, bio-waste pyrolysis, supercritical water treatment, etc.
Assuntos
Automação/métodos , Cromatografia Gasosa/métodos , Ionização de Chama/métodos , Hidrocarbonetos/química , Compostos de Enxofre/química , Catálise , Petróleo/análiseRESUMO
The present research is based on the development of an effective, environmentally-friendly and low-cost method for investigation of minor components in vegetable oils, exploiting the advantages of a miniaturized solid-phase extraction (SPE) and the potential of flow modulation (FM) comprehensive two-dimensional gas chromatography (GC×GC), coupled to a mass spectrometer (MS) and a flame ionization detector (FID). The initial sample preparation step was carried out using a miniaturized approach characterized by a SPE process in a Pasteur pipette. Then, the isolated fraction was injected into an FM GC×GC system. Tentative identification was carried out by means of MS spectral information, while quantification was carried out by using the FID data. Four different vegetable oil samples were analyzed using the proposed method, namely an extra virgin olive oil (EVO), a hazelnut oil (HO), a borage oil, and an EVO/HO mixture.
Assuntos
Cromatografia Gasosa/métodos , Ionização de Chama/métodos , Contaminação de Alimentos/análise , Espectrometria de Massas/métodos , Óleos de Plantas/análise , Extração em Fase Sólida/métodosRESUMO
Short-chain fatty acids, such as acetic, propionic, butyric, iso-valeric and valeric acids, play an important role in methanogenesis activity for biogas production processes. Thus, simple and rapid procedures for monitoring the levels of short-chain fatty acids are requisite for sustaining biogas production. This work presents the development of a sequential injection-liquid microextraction (SI-LME) procedure with GC-FID analysis for determination of short-chain fatty acids. GC-FID was employed for detection of the short-chain fatty acids. Calibration curves were linear with good coefficients of determination (r2>0.999), using methacrylic acid as the internal standard. Limits of quantification (LOQ) were in the range of 0.03-0.19mM. The SI-LME procedure employed tert-butyl methyl ether (TBME) as the extracting solvent. Various SI-LME conditions were investigated and optimized to obtain the highest recovery of extraction. With these optimized conditions, an extraction recovery of the five key short-chain fatty acids of 67-90% was obtained, with less than 2% RSD (n=3). The final SI-LME procedure employed two fluidic zones of TBME with a single aqueous fluidic zone of sample sandwiched between the TBME zones, with 5 cycles of flow reversal at a flow rate of 5µL/s for the extraction process. Intra- and inter-day precision values were 0.5-4.0% RSD and 3.3-4.8% RSD, respectively. Accuracy based on percentage of sample recovery were in the range of 69-96, 102-107, and 82-101% (n=4) for acetic, propionic and butyric acids, respectively. The proposed method was applied for the measurement of short-chain fatty acids in palm oil mill effluents used in biogas production in a factory performing palm oil extraction process. The SI-LME method provides improved extraction performance with high precision, and is both simple and rapid with its economical extraction technique. The SI-LME procedure with GC-FID has strong potential for use as a quality control process for monitoring short-chain fatty acid levels in biogas production.
Assuntos
Cromatografia Gasosa/métodos , Ácidos Graxos Voláteis/análise , Ionização de Chama/métodos , Microextração em Fase Líquida/métodos , Óleo de Palmeira/análise , Eliminação de Resíduos Líquidos/métodos , Óleo de Palmeira/químicaRESUMO
The shift to heavy crude oils and the use of alternative fossil resources such as shale oil are a challenge for the petrochemical industry. The composition of heavy crude oils and shale oils varies substantially depending on the origin of the mixture. In particular they contain an increased amount of nitrogen containing compounds compared to the conventionally used sweet crude oils. As nitrogen compounds have an influence on the operation of thermal processes occurring in coker units and steam crackers, and as some species are considered as environmentally hazardous, a detailed analysis of the reactions involving nitrogen containing compounds under pyrolysis conditions provides valuable information. Therefore a novel method has been developed and validated with a feedstock containing a high nitrogen content, i.e., a shale oil. First, the feed was characterized offline by comprehensive two-dimensional gas chromatography (GC × GC) coupled with a nitrogen chemiluminescence detector (NCD). In a second step the on-line analysis method was developed and tested on a steam cracking pilot plant by feeding pyridine dissolved in heptane. The former being a representative compound for one of the most abundant classes of compounds present in shale oil. The composition of the reactor effluent was determined via an in-house developed automated sampling system followed by immediate injection of the sample on a GC × GC coupled with a time-of-flight mass spectrometer (TOF-MS), flame ionization detector (FID) and NCD. A novel method for quantitative analysis of nitrogen containing compounds using NCD and 2-chloropyridine as an internal standard has been developed and demonstrated.
Assuntos
Cromatografia Gasosa/métodos , Hidrocarbonetos/análise , Medições Luminescentes/métodos , Espectrometria de Massas/métodos , Compostos de Nitrogênio/análise , Ionização de Chama/métodos , Petróleo/análise , Piridinas/químicaRESUMO
The profile of minor compounds, such as alcohols, sterols, free and alkyl fatty acids, waxes, etc., was investigated in different vegetable oils by a comprehensive gas chromatographic system, coupled with a simultaneous dual detection (flame ionisation detector and mass spectrometer) for quantitative and qualitative purposes. Such a system generated a unique two-dimensional chromatogram to be used as a chemical fingerprint. Multi-level information, due not only to a more "comprehensive" preparation technique, but also thanks to the exploitation of a more powerful and sensitive analytical determination allowed the extrapolation of diagnostic information from the minor components profile of different vegetable oils, along with their characteristic profile. Furthermore, an admixture of an extra virgin olive oil with a low amount of sunflower and palm oils was evaluated, attesting to the powerful diagnostic information provided by the proposed approach.
Assuntos
Cromatografia Gasosa/métodos , Ácidos Graxos/análise , Ionização de Chama/métodos , Espectrometria de Massas/métodos , Óleos de Plantas/análise , Óleos de Plantas/química , Esteróis/análiseRESUMO
Despite efforts by many dietary supplements' manufactures to reduce or replace ethanol, many products containing ethanol in concentrations up to 70% are available on market. Furthermore, botanical dietary supplements can vary in metal content as a function of the environment, processing equipment and product containers. Therefore, the aim of study was to develop a new rapid and highly sensitive method for simultaneous determination of ethanol and its impurities in dietary supplements by sHSS-GC-FID technique. In addition, contamination with metals by GFAAS technique was evaluated. The proposed sHSS-GC-FID method was successfully applied for analysis of 93 samples containing various amounts of ethanol. It should be highlighted that the dramatic variation from manufacture's claims was found in even one third of products. Furthermore, high amounts of ethanol were found in several products especially designed for children and in one product labeled as "alcohol-free". Metal impurities were below the limits established by USP.
Assuntos
Suplementos Nutricionais/análise , Etanol/análise , Contaminação de Alimentos/análise , Metais/análise , Espectrofotometria Atômica/métodos , Cromatografia Gasosa/métodos , Ionização de Chama/métodosRESUMO
A novel method for the measurement of total phytosterols in fortified food was developed and tested using gas chromatography with flame ionization detection. Unlike existing methods, this technique is capable of simultaneously extracting sterols during saponification thus significantly reducing extraction time and cost. The rapid method is suitable for sterol determination in a range of complex fortified foods including milk, cheese, fat spreads, oils and meat. The main enhancements of this new method include accuracy and precision, robustness, cost effectiveness and labour/time efficiencies. To achieve these advantages, quantification and the critical aspects of saponification were investigated and optimised. The final method demonstrated spiked recoveries in multiple matrices at 85-110% with a relative standard deviation of 1.9% and measurement uncertainty value of 10%.
Assuntos
Ionização de Chama/métodos , Alimentos Fortificados/análise , Fitosteróis/análise , Animais , Fracionamento Químico , Carne/análise , Leite/química , Óleos de Plantas/análiseRESUMO
A sensitive and rapid analytical method has been validated for the enantiomeric purity determination of l-pidolic acid, a biological lactam and metabolite of glutamic acid commonly found in urine, skin, bones, brain and is available commercially as a food supplement. An efficient, two-step achiral derivatization was implemented which consisted of an alkylation step (using HCl-IPA) followed by an acylation step (using TFAA) of the carboxy and amide functional groups. This allowed detection with high sensitivity using gas chromatography with flame ionization detection. The described procedure employs a CP-Chiralsil-L Val column (25m×0.25mm) at a constant flow rate of 1.5mLmin(-1), a gradient temperature program from 80°C to 160°C and an injector and detector temperature of 250°C. The proposed method was validated according to ICH Q2 standards and included such parameters as specificity, system precision, analyst repeatability, intermediate precision, accuracy, linearity, LOD/LOQ and solution stability.
Assuntos
Ácido Pirrolidonocarboxílico/química , Cromatografia Gasosa/métodos , Suplementos Nutricionais/análise , Ionização de Chama/métodos , Sensibilidade e Especificidade , EstereoisomerismoRESUMO
Amomum maximum Roxb. is a perennial herb distributed in South China and Southeast Asia. The objective of this work was to analyze the chemical constituents and assess insecticidal and repellent activities of the essential oil from Amomum maximum fruits against Tribolium castaneum (Herbst) and Liposcelis bostrychophila (Badonnel). The essential oil was obtained by hydrodistillation and analyzed by gas chromatography-flame ionization detector and gas chromatography-mass spectrometry. The main components of the essential oil were identified to be ß-pinene (23.39%), ß-caryophyllene (16.43%), α-pinene (7.55%), sylvestrene (6.61%) and ç-cadinene (4.19%). It was found that the essential oil of A. maximum fruits possessed contact and fumigant toxicities against T. castaneum adults (LD50 = 29.57 µg/adult and LC(50) = 23.09 mg/L air, respectively) and showed contact toxicity against L. bostrychophila (LD(50) = 67.46 µg/cm(2)). Repellency of the crude oil was also evaluated. After 2 h treatment, the essential oil possessed 100% repellency at 78.63 nL/cm(2) against T. castaneum and 84% repellency at 63.17 nL/cm(2) against L. bostrychophila. The results indicated that the essential oil of A. maximum fruits had the potential to be developed as a natural insecticide and repellent for control of T. castaneum and L. bostrychophila.
Assuntos
Amomum/química , Repelentes de Insetos , Inseticidas , Óleos Voláteis/isolamento & purificação , Óleos Voláteis/farmacologia , Óleos de Plantas/isolamento & purificação , Óleos de Plantas/farmacologia , Tribolium/efeitos dos fármacos , Animais , Sudeste Asiático , Monoterpenos Bicíclicos , Compostos Bicíclicos com Pontes/análise , Compostos Bicíclicos com Pontes/isolamento & purificação , Compostos Bicíclicos com Pontes/farmacologia , Compostos Bicíclicos com Pontes/toxicidade , China , Destilação/métodos , Ionização de Chama/métodos , Frutas/química , Fumigação , Cromatografia Gasosa-Espectrometria de Massas , Dose Letal Mediana , Monoterpenos/análise , Monoterpenos/isolamento & purificação , Monoterpenos/farmacologia , Monoterpenos/toxicidade , Óleos Voláteis/análise , Óleos Voláteis/toxicidade , Óleos de Plantas/análise , Óleos de Plantas/toxicidade , Sesquiterpenos Policíclicos , Sesquiterpenos/análise , Sesquiterpenos/isolamento & purificação , Sesquiterpenos/farmacologia , Sesquiterpenos/toxicidadeRESUMO
Development of authenticity screening for Asian palm civet coffee, the world-renowned priciest coffee, was previously reported using metabolite profiling through gas chromatography/mass spectrometry (GC/MS). However, a major drawback of this approach is the high cost of the instrument and maintenance. Therefore, an alternative method is needed for quality and authenticity evaluation of civet coffee. A rapid, reliable and cost-effective analysis employing a universal detector, GC coupled with flame ionization detector (FID), and metabolite fingerprinting has been established for discrimination analysis of 37 commercial and non-commercial coffee beans extracts. gas chromatography/flame ionization detector (GC/FID) provided higher sensitivity over a similar range of detected compounds than GC/MS. In combination with multivariate analysis, GC/FID could successfully reproduce quality prediction from GC/MS for differentiation of commercial civet coffee, regular coffee and coffee blend with 50 wt % civet coffee content without prior metabolite details. Our study demonstrated that GC/FID-based metabolite fingerprinting can be effectively actualized as an alternative method for coffee authenticity screening in industries.
Assuntos
Café/química , Café/metabolismo , Ionização de Chama/métodos , Metaboloma , Viverridae , Animais , Café/normas , Análise Discriminante , Indústria Alimentícia/métodos , Cromatografia Gasosa-Espectrometria de Massas/economia , Análise Multivariada , Padrões de ReferênciaRESUMO
A homemade flow cell attached to a commercial Gas Chromatograph equipped with a Flame Ionization Detector (FID) has been designed for the continuous monitoring of volatile compounds released during heating edible oils. Analytical parameters such as mass of sample, temperature and flow rates have been optimized and the obtained results have been compared with the corresponding thermographs from standard TG systems. Results show that under optimum conditions, the profiles of volatiles released upon heating are comparable to the profiles of TG curves, suggesting that the FID based system could be an alternative to TGA. Additionally, volatiles have been retained in a Lichrolut EN(®) resin, eluted and analyzed by Gas Chromatography-Mass Spectrometry. In this case, forty five compounds have been identified (acids, alcohols, alkanes, aldehydes, ketones and furans) and compared with the FID signals, working both in air or nitrogen atmosphere. It has been concluded that the oxidative thermal degradation is prevented in the presence of a nitrogen atmosphere.