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Namratha, Sunkara*, Manisha B., Harshita B., Anjali B., Ishwarya B., and Akhila B. "REVIEW ARTICLE GAS – CHROMATOGRAPHY (GC)." World Journal of Pharmaceutical Science and Research 3, no. 1 (2024): 23–26. https://doi.org/10.5281/zenodo.10939869.
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Gas chromatography is a term used to describe the group of analytical separation technique used to analyze volatile substance in the gas phase. In gas chromatography, the components of a sample are dissolved in a solvent and vaporized in order to separate the analyte by distributing the sample between two phases: a stationary phase and a mobile phase. The mobile phase is chemically inert gas that serves to carry the molecules of the analyte through the heated column. Gas chromatography is one of the sole forms of chromatography that does not utilize the mobile phase for interacting with the analyte. The stationary phase is either a solid adsorbant, termed gas-solid chromatography (GSC), or a liquid on an inert support termed gas - liquid chromatography (GLC). Gas chromatography is an instrumental technique used forensically in drug analysis, arson, toxicology analyse of other organic compounds.
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Nilam A.Nikam, Nilam A. Nikam, Sandhya P. Kadam Sandhya P.Kadam, and Dr Vivek Kumar K. Redasani Dr. Vivek Kumar K.Redasani. "A Comprehensive Review on Gas chromatography." International Journal of Pharmaceutical Research and Applications 10, no. 3 (2025): 18–33. https://doi.org/10.35629/4494-10031833.
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Gas chromatography is the general term for a range of analytical separation techniques used to analyze volatiles in the gas phase. Gas chromatography separates the analytes by separating the sample into two phases, the stationary phase and the mobile phase, by dissolving the sample components in a solvent and evaporating them. The mobile phase is chemically inertGas, which transports the analyte molecules through the heated column.Gas Chromatography is one of the only chromatography's that interacts with analytes without the use ofMobile phases. The stationary phase is either a solid adsorbent, calledGas-Solid Chromatography (GSC), or a liquid on an inert support, called GasLiquidChromatography (GLC). Gas chromatography is an instrumental technique used forensically in drug analysis, arson, and toxicology analysis of other organic compounds.
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Li, Bincai(Pun Choi). "Studies of Polymer Properties via Inverse Gas Chromatography." Rubber Chemistry and Technology 69, no. 3 (1996): 347–76. http://dx.doi.org/10.5254/1.3538377.
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Abstract Gas Chromatosraphy (GC) using a polymer as the stationary phase to reveal the properties of the polymer — known as Inverse Gas Chromatography (IGC) — is in contrast to conventional GC where gaseous components in the mobile phase are separated and studied. Figure l(a) and l(b) are schematic diagrams showing the arrangement of apparatus in a gas Chromatograph for IGC. The column is filled with packings consisting of thin layer of polymer coated onto an inert support, typically Chromosorb W, Chromosorb G (70 ∼ 80 mesh, acid washed and dimethyldichlorosilane treated), or Teflon. The carrier gas, such as N2, H2, or He, acts as the mobile phase. The solvent, injected as a sharp pulse and vaporized immediately into the carrier gas stream at the entrance of the column, is called the probe. As the probe is carried forward, it is partitioned between the mobile gas phase and the stationary polymer phase. The time required to elute the probe through the column is called the retention time (elution is monitored in the detector and reflected on the recorder or integrator as a peak maximum). The corresponding amount of carrier gas needed is called the retention volume. The detector for the probe may be a thermal conductivity cell (TCD) or flame ionization detector (FID). When an FID is used, the flow of gas is diverted to the flow meter before it reaches the detector as shown in Figure l(b). Some notes on the experimental techniques will be discussed in Section IX. GC has been classified into Gas-Liquid Chromatography (GLC) and Gas-Solid Chromatography (GSC) according to whether the stationary phase is a liquid or a solid, respectively. In IGC, the process is GLC when the temperature of the polymer under investigation is far above its glass transition temperature Tg. The retention is due to absorption of the solvent vapor into the polymer bulk (an amorphous polymer above Tg is viewed as a liquid). When the temperature of the polymer is well below its Tg, the process is GSC and the retention mechanism becomes adsorption of the vapor onto the polymer surface. We shall initially discuss the GLC of polymers and then extend our discussions to GSC. Important applications of IGC to polymer research have been the studies of the thermodynamics of polymer-solvent and polymer-polymer interactions via GLC.
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Kirtimaya, Mishra* Dr. K. Balamurugan1 Dr. R. Suresh1. "A REVIEW: AN APPROACH TOWARDS THE ANALYTICAL METHOD DEVELOPMENT FOR DETERMINATION OF NEWER DRUGS." INDO AMERICAN JOURNAL OF PHARMACEUTICAL RESEARCH 07, no. 01 (2017): 7353–60. https://doi.org/10.5281/zenodo.1006749.
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In this present scenario for treating various diseases several new drugs were invented. Before launching to the market these drugs must undergo analytical validation process. In this review some of analytical techniques such as ultraviolet/ visible spectrophotometry, fluorimetry, capillary electrophoresis, and chromatographic methods (gas chromatography and high-performance liquid chromatography), LC-MS, GC-MS, SOLID PHASE EXTRACTION, NMR, MASS Spectrophotometry LC/MS/MS LC/UV X-ray crystallography were discussed.
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Abeer, Fauzi Al-Rubaye, Hadi Hameed Imad, and Jawad Kadhim Mohanad. "A Review: Uses of Gas Chromatography-Mass Spectrometry (GC-MS) Technique for Analysis of Bioactive Natural Compounds of Some Plants." International Journal of Toxicological and Pharmacological Research 9, no. 1 (2017): 81–85. https://doi.org/10.5281/zenodo.12754849.
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Chromatography is the term used to describe a separation technique in which a mobile phase carrying a mixture is caused to move in contact with a selectively absorbent stationary phase. It also plays a fundamental role as an analytical technique for quality control and standardization of phyto therapeuticals. Gas Chromatography is used in the separation and analysis of multi component mixtures such as essential oils, hydrocarbons and solvents. Various temperature programs can be used to make the readings more meaningful; for example to differentiate between substances that behave similarly during the GC process. Intrinsically, with the use of the flame ionization detector and the electron capture detector (which have very high sensitivities) gas chromatography can quantitatively determine materials present at very low concentrations. Plants are a rich source of secondary metabolites with interesting biological activities. In general, these secondary metabolites are an important source with a variety of structural arrangements and properties. Gas chromatography – specifically gas-liquid chromatography – involves a sample being vapourised and injected onto the head of the chromatographic column. The sample is transported through the column by the flow of inert, gaseous mobile phase. The column itself contains a liquid stationary phase which is adsorbed onto the surface of an inert solid. The principle of gas chromatography is adsorption and partition. Within the family of chromatography- based methods gas chromatography (GC) is one of the most widely used techniques. GC-MS has become a highly recommended tool for monitoring and tracking organic pollutants in the environment. GC-MS is exclusively used for the analysis of esters, fatty acids, alcohols, aldehydes, terpenes etc. It is the key tool used in sports anti-doping laboratories to test athlete’s urine samples for prohibited performanceenhancing drugs like anabolic steroids. Several GC-MS have left earth for the astro chemistry studies. <strong> </strong>As a unique and powerful technology the GC-MS provides a rare opportunity to perform the analysis of new compounds for characterization and identification of synthesized or derivatized compound.
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Rudakov, Yaroslav O., Vladimir F. Selemenev, Ludmila V. Rudakova, and Oleg B. Rudakov. "Chromatographic approaches to food quality control by chemical compo-sition." Сорбционные и хроматографические процессы 24, no. 2 (2024): 197–208. http://dx.doi.org/10.17308/sorpchrom.2024.24/12125.
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The article provides an overview of chromatographic methods, which, when used comprehensively, ensure food quality control and safety. It considers gas chromatography methods that allow analysing volatile components in products using a flame ionization detector, an electron capture detector, and mass-selective detectors (GC-FID, GC-ECD, GC-MS, and GC-MS/MS). The article provides a list of analytes that can be detected by high performance liquid chromatography in combination with refractometric, spectrometric, and mass selective detectors (HPLC-RMD, HPLC-UV, HPLC-SPD, HPLC-MS, and HPLC-MS/MS). The study showed how ion chromatography and capillary electrophoresis with electrochemical detectors (IC-ECD, CE-ECD) can be used to detect ionogenic compounds. It highlighted the importance of thin layer chromatography (TLC) in combination with optical digital colour recording devices in the qualitative and quantitative analysis of contaminants in food products. Since it has been established that micro- and nanoplastics have a negative impact on human health, it is very important to detect these particles in food products. This task can be solved by using gel permeation chromatography (GPC) and hydrodynamic chromatography (HDC), as well as the method of field-flaw fractionation (FFF). It was shown that the GC-MS method is now becoming a priority instrumental method used in accredited analytical laboratories to identify impurities of contaminants in agricultural products. The pyrolytic GC-MS method is promising in this regard. The pyrolytic cell does not require the transfer of a solid sample into a solution for its analysis. The paper considers extraction and sorption methods for the preparation of samples for chromatographic analysis. A variety of liquid-liquid extraction (LLE) and solid-phase extraction (SPE.) methods are most commonly used. Recently, the QuEChERS method has been developed and widely implemented. The overview is primarily based on the papers dedicated to chromatography and related separation methods published by researchers belonging to Voronezh scientific schools.
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Ivanova, Yu A., Z. A. Temerdashev, I. A. Kolychev, and N. V. Kiseleva. "Determination of polymeric functional additives in diesel fuel by gel penetration chromatography." Аналитика и контроль 25, no. 1 (2021): 53–62. http://dx.doi.org/10.15826/analitika.2020.25.1.003.
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Current article is devoted to the development of a method for determining polymer functional additives and their molecular weight characteristics in diesel fuel by gel penetration chromatography. The objects of the study were solutions of “C5A”, “Maxoil D”, “Detersol”, polymethymethacrylate “D” (PMAD), “Keropur D ”, Antigel “Difron 3319” and “Superantigel” individual additives as well as the diesel fuel produced by the “Kuban Oil and Gas Company - Ilskiy Oil Refinery”, LLC. The conditions for chromatographic separation and determination of polymeric functional additives were determined considering the analyzed fuel matrix, the working range of the separated masses and molecular weights of analytes, and the composition of the eluent applicable for wide range of analytes. The chromatographic system was calibrated using the narrowly dispersed analytical standard polystyrene samples with molecular weights of 1000, 2000, 4000, 10000, 30,000, 50,000, and 70,000 Da respectively. The molecular weight characteristics were calculated for each functional additive from the analytical standard samples of polystyrene. The method of GPC determination of polymeric functional additives in diesel fuel, along with the concentration characteristics, also makes it possible to determine the molecular weight parameters of wide range of polymeric functional additives; therefore, it is promising for monitoring the quality of the diesel fuel. The proposed analytical scheme was tested in the analysis of real sample of diesel fuel. The GPC scheme for the determination of the “Keroflux 3699” depressant-dispersant additive in diesel fuel included sample preparation using the solid-phase extraction, calibration of the chromatographic system using the standard polystyrene samples, GPC determination of additive components, and the calculation of molecular weight characteristics. The molecular weight characteristics of the “Keroflux 3699” depressant dispersant additive in diesel fuel have been established - the number average and weight average molecular weights equivalent to polystyrene were 10,300 and 8800 Da respectively, and the polydispersity index of the additive was 1.17.
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He, Wei, Yanru Chen, Chen Yang, et al. "Optimized Multiresidue Analysis of Organic Contaminants of Priority Concern in a Daily Consumed Fish (Grass Carp)." Journal of Analytical Methods in Chemistry 2017 (2017): 1–13. http://dx.doi.org/10.1155/2017/9294024.
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The organic contaminants, including polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs), polybrominated diphenyl ethers (PBDEs), and polychlorinated biphenyls (PCBs), are of priority concern because of their persistence, toxicity, and long-distance transportation in global environment. Their residues in a daily consumed fish (grass carp) pose potential threat to human health and aquatic ecosystems. The present study optimized an analytical protocol of microwave-assisted extraction (MAE), lip-removal by gel permeation chromatography (GPC), cleanup by solid phase cartridge (SC) or adsorption chromatography column (CC), and gas chromatography-mass spectrometry (GC/MS). Besides traditional statistical parameters, some indicators were calculated to judge the performances of extraction by various methods. The optimization experiment showed that n-hexane/acetone was the best MEA extraction solvent; an optimal fraction time of 10–39 min could simultaneously elute all the target chemicals in a single GPC run. Both CC and SC showed good recoveries. However, CC performed better than SC (p<0.05) for OCPs, and SC performed better than CC for PBDEs (p<0.05). We also emphasized the limitations and advantages of SC and CC and finally proposed SC as the promising cleanup method because of its low-cost materials, time-saving steps, being free of manual filling, and operation by automated SPE system.
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Zhang, Chang Ming, and Xiao Li Su. "Multiple-Instrument Analysis and their Relationship with Process Development." Advanced Materials Research 699 (May 2013): 371–77. http://dx.doi.org/10.4028/www.scientific.net/amr.699.371.
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The waste polymer-polyethylene (PE) was treated in a supercritical water (SCW) system under different operation conditions (such as temperature, heat rate and ratio of water and PE material). The obtained liquid oil products and solid-products were analyzed by conjunct methods including high performance gel penetration chromatography (GPC), Fourier transform infrared spectroscopy (FTIR) and gas chromatography (GC). A relationship of the characteristics of the products and the operation conditions in waste treatment was established. The results of FTIR and GC analyses indicated that the liquid oil products contain a large amount of alkanes, which are suitable for using as fuel oil. Through a series of experiments, the optimum operation conditions were defined as follows：The amount of PE sample: 6g, H2O/PE ratio: 6/1, the reaction temperature (Tem): 460° C, heating rate (Vt): 7.66 (°C / second), the yield of products: 86.0%.
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Rakitskii, V. N., N. E. Fedorova, V. V. Bayusheva, O. E. Egorchenkova, and L. G. Bondareva. "DETERMINATION OF 2,4-D IN SOME FOOD PRODUCTS (MILK, EGGS, LIVER, KIDNEYS) BY CHROMATOGRAPHY METHODS." Toxicological Review, no. 1 (February 28, 2018): 20–25. http://dx.doi.org/10.36946/0869-7922-2018-1-20-25.
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The modern technique for the determination of 2,4-D, that belongs to global environmental pollutants, including the use of the technology of sample preparation - dispersive solid-phase-liquid extraction (QuEChERS), new for products of animal origin, has been developed. The sample preparation procedure includes the steps of: preliminary freezing of the sample to be analyzed, extraction with acetonitrile containing 1% acetic acid in the presence of MgSO4 and NaCl, purification by dispersive solid-phase extraction using a mixture of sorbents based on primarysecondary amine, octadecylsilane and graphitized carbon black, the freeze of the solution - at the last stage. Using the proposed technique allows to isolate the desired component from a matrix with a high content of animal fat into a selected organic solvent with high efficiency, that made it possible to expand significantly the arsenal of analytical equipment used to detect residual amounts of 2,4-D in food products of agricultural production, for example milk, eggs and offal (liver, kidney): tandem liquid mass-spectrometry (HPLC-MS/MS), gas-liquid chromatography with mass-selective and electron-capture detectors (GLC-MSD, GLC-ECD). The lower limit of the quantitative determination is 2,4-D: 0,005 mg/kg for milk and eggs, 0.05 mg/kg for the liver and kidneys. Completeness of extraction is 85-94%, RMS of repeatability is 3,4-11,4%.
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Naseem, Zahra, Khalid Saeed Muhammad, and Hassan Raza Muhammad. "Nitrosamines: Incredibly unsafe contaminants in different food commodities." Chemistry International 9, no. 1 (2023): 27–36. https://doi.org/10.5281/zenodo.7370412.
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N-nitrosamines are an incredibly unsafe class of mixtures. The chance of the event of these mixtures in our food and in other ecological circumstances has caused worry over the previous decade. They are carcinogenic as well as mutagenic. Both tertiary and secondary amines react with nitro-sating substances to produce nitrosamines. Nitrosamine is most commonly present in food and water. It was first time discovered in 1863 in second amine that reacts with nitrite Volatile nitrosamines present in food are notrosodimethylamines while nonvolatile nitrosamines are not yet confirmed due to lack of analytical methodology. Solid phase extraction, mass spectrometry, gas chromatography and liquid chromatography are commonly used methods of nitrosamine determination. FDA has recommended permissible level of nitrosamines impurities of daily intake in different items. Vitamin C and different nutrients can prevent the transformation of nitrates and nitrites into nitrosamines.
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Zhou, Yuran, Bin Wen, and Bei Liu. "Effect of Pd/C catalytic extraction on the hydrothermal depolymerization properties of ethanol organosolv lignin (EOL) in supercritical ethanol." BioResources 18, no. 3 (2023): 4567–79. http://dx.doi.org/10.15376/biores.18.3.4567-4579.
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This study investigated the effect of a Pd/C catalytic extraction process on the hydrothermal depolymerization product properties of ethanol organosolv lignin (EOL) in supercritical ethanol. Phenolic products were separated and analyzed by gel permeation chromatography (GPC) and thermogravimetric (TG) analyses. The gas chromatography–mass spectrometry (GC-MS) analyses of obtained liquid oil products from depolymerized EOL confirmed the presence of value-added phenolics. Scanning electron microscopy (SEM) was used to observe the morphology of the char product. During ethanol organosolv lignin extraction, 90.5% purity of EOL was obtained. A high yield of EOL up to 39.6% from bamboo without catalysts and with higher yield of EOL up to 44.0% from 1% Pd/C catalyst under 200 °C. A high yield of liquid oil products, up to 65.4%, was recovered from EOL depolymerization under conditions of 240 °C, 240 min, 100 vol % ethanol, and 2% EOL, with only 24% solid residue. The main phenolic products were 2-methoxyphenol, 4-ethylphenol, 4-methoxy-2-methylphenol, 4-ethyl-2-methoxyphenol, 2,6-dimethoxy-phenol, and 2-methoxy-4-propylphenol.
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Wood, William F. "Dimethyl sulphide: The oyster-like odourant of Mertensia maritima." Biosystematics and Ecology 2 (November 13, 2023): e113169. https://doi.org/10.1553/biosystecol.2.e113169.
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The oyster plant (Britain) or oyster leaf (North America), <i>Mertensia maritima</i> (L.) Gray has a strong oyster-like odour. Headspace volatiles from fresh crushed leaves of this plant were analysed using solid phase microextraction (SPME) and gas chromatography–mass spectrometry (GC–MS). Dimethyl sulphide was detected emanating from the crushed leaves, a compound that is noted for being a major part of the odour profile of raw oysters.
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Wood, William F., David L. Largent, and Darvin A. DeShazer. "The cooked shellfish-odour of the mushroom Russula xerampelina." Biosystematics and Ecology 3 (January 29, 2024): e115244. https://doi.org/10.1553/biosystecol.3.e115244.
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The "shrimp mushroom", <i>Russula xerampelina</i>, has a strong cooked shellfish odour. Headspace volatiles from fresh sporocarps of this mushroom were analysed using solid phase microextraction (SPME) and gas chromatography–mass spectrometry (GC–MS). Trimethylamine and trimethylamine <i>N</i>-oxide were the only volatile compounds detected emanating from the fruiting body. Trimethylamine is noted for its fishy, cooked crab or cooked shrimp-like odour. Graphical Abstract
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Ferreiro, Cristian, Natalia Villota, José Ignacio Lombraña, and María J. Rivero. "Heterogeneous Catalytic Ozonation of Aniline-Contaminated Waters: A Three-Phase Modelling Approach Using TiO2/GAC." Water 12, no. 12 (2020): 3448. http://dx.doi.org/10.3390/w12123448.
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This work aims to study the sustainable catalytic ozonation of aniline promoted by granular active carbon (GAC) doped with TiO2. Aniline was selected as a model compound for the accelerator manufacturing industries used in the manufacture of rubber due to its environmental impact, low biodegradability, and harmful genotoxic effects on human health. Based on the evolution of total organic carbon (TOC), aniline concentration measured using high performance liquid chromatography (HPLC), pH and ozone concentration in liquid and gas phase, and catalyst loading, a three-phase reaction system has been modelled. The proposed three-phase model related the ozone transfer parameters and the pseudo-first order kinetic constants through three coefficients that involve the adsorption process, oxidation in the liquid, and the solid catalyst. The interpretation of the kinetic constants of the process allowed the predominance of the mechanism of Langmuir–Hinshelwood or modified Eley–Rideal to be elucidated. Seven intermediate aromatic reaction products, representative of the direct action of ozone and the radical pathway, were identified and quantified, as well as precursors of the appearance of turbidity, with which two possible routes of degradation of aniline being proposed.
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Celeiro, Maria, Laura Rubio, Carmen Garcia-Jares, and Marta Lores. "Miniaturized Sample Preparation Methods to Simultaneously Determine the Levels of Glycols, Glycol Ethers and Their Acetates in Cosmetics." Cosmetics 8, no. 4 (2021): 102. http://dx.doi.org/10.3390/cosmetics8040102.
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Two environmentally friendly methodologies based on ultrasound-assisted extraction (UAE) and micro-matrix solid-phase dispersion (µMSPD) followed by gas chromatography-mass spectrometry (GC-MS) analysis are proposed for the first time for the simultaneous analysis of 17 glycols, glycol ethers, and their acetates in cosmetics. These sample preparation approaches result in efficient and low-cost extraction while employing small amounts of sample, with a low consumption of reagents and organic solvents. The use of a highly polar column allows for the direct analysis of the obtained extracts by GC-MS without a previous derivatization step, drastically reducing the sample preparation time and residues and thus complying with green analytical chemistry (GAC) principles. Both the UAE and µMSPD methodologies were validated in terms of linearity, accuracy, and precision, providing satisfactory results. LODs were found to be lower than 0.75 µg g−1, allowing the determination of trace levels of the forbidden target compounds. Finally, the validated methodologies were applied to real cosmetics and personal care products, showing suitability, and providing a reliable and useful tool for cosmetics control laboratories.
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Andreev, A. A., N. A. Belov, V. V. Makarova, et al. "Dispersion of Polyethylene Glycol in Perfluorodecalin for Liquid Phase Fluorination." Eurasian Chemico-Technological Journal 24, no. 3 (2022): 259–65. http://dx.doi.org/10.18321/ectj1439.
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This work aims to obtain the dispersions based on polyethylene glycols (PEGs) of various molecular masses (MM) and perfluorodecalin (PFD) for subsequent direct fluorination. The solubility of the components was estimated using laser interferometry and differential scanning calorimetry, and it was shown that PEGs with different MM are not highly compatible with PFD. The dispersions were prepared during sonication. Gel permeation chromatography (GPC) analysis indicated that MMs almost did not change in this process. While the sonication of PEG-PFD, there is a formation of dispersion with the particle sizes distribution in a range of 0.4‒2 μm depending on the MM of PEG. The dispersion is metastable for several hours, even though its stability was significantly affected by additional bubbling with the gas flow. Moreover, the dispersions with a solid PEG phase (MM > 600 Da) were subjected to a smaller change compared to a liquid one (MM < 600 Da). The results of this research shed light on the applicability of the ultrasonic preparation of PEGs in PFD for liquid-phase fluorination with obtaining perfluorinated polyether of target MM.
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Festus-Amadi, Ijeoma, O. Destiny Erhabor, Christiana E. Ogwuche, and Obruche K. Erienu. "Characterization of Contaminated Sediments Containing Polycyclic Aromatic Hydrocarbons from Three Rivers in the Niger Delta Region of Nigeria." Chemistry Research Journal 6, no. 3 (2021): 1–12. https://doi.org/10.5281/zenodo.11653922.
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<strong>Abstract </strong>In this study, 16 priority polycyclic aromatic hydrocarbons (PAHs) were determined in sediment samples in three Rivers (i.e. Orashi River, Aluu River and Woji River) in Port Harcourt, River State Nigeria. Pretreatment of the samples were performed to increase the homogeneity of the soil and to increase the extractability of the analytes in the sediment was carried out using dichloromethane. The samples were extracted using the soxhlet extractor and clean-up by Solid phase extraction (SPE) clean up, using a 12- port vacuum manifold from SUPELCO with 6 mL Supelco C18 SPE cartridges. Under the optimized conditions, the ranges of extraction recoveries and SPE clean-up of the PAHs in the sediments were in the range of 71-90%. Gas chromatography-mass spectrometry (GC-MS) was used for the extraction and determination of the 16 PAHs in the samples. The method prescribed United States Environmental Protection Agency (USEPA) priority polycyclic aromatic hydrocarbons (PAHs) was used throughout the analysis. The detection of PAHs in the present study shows that there are serious pollutants in the water and sediments; it also indicates the inefficiency of water resources management in the three Rivers in Port Harcourt, River state Nigeria.
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L.E., Attah, and Biyana Melkamu. "GC-MS Determination of Pesticide Residues in Effluent Run-off, River and Adjacent Soil around a Floriculture Industry in Holetta Town, Ethiopia." Journal of Science and Sustainable Development 1, no. 2 (2013): 25–40. https://doi.org/10.20372/au.jssd.1.2.2013.015.
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A variety of organophosphorous and organochlorine pesticides residues have been assessed in the effluent, river and adjacent soil around a floriculture industry in Holetta Town West Shoa Zone, Ethiopia. Extraction of the pesticides was carried out by solid-phase extraction (SPE), and quantification was carried out by Gas Chromatography-Mass Spectrometry (GC-MS). Pesticides recoveries ranged from 80-101% in water and 64-99.9% in soil samples after 1 week aging. The mean concentrations of dominant pesticides (carbofuran, propyzamide, oxamyl, chlorothalonil, endosulfan(α) and kerosoxim-methyl) follow the sequence: effluent>soil>river , ranging from 0.268 - 4.655 mg/L in the effluent, 0.066 - 2.800 mg/kg in the soil and 0.043 - 1.191 mg/L in the river sample except for malathion, fludioxonil, and p,p’-DDT which had higher concentrations in river than soil. Pesticide concentrations in all samples were above the maximum residue limit (MRL) set by EU for total pesticides concentration. The results of this study suggested that both the river and adjacent soil have been contaminated with the pesticides from the floriculture effluent run-off, which could result in adverse biological effect on the ecosystem.
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Билялова, А. С., А. Д. Малинкин, В. А. Саркисян, А. А. Кочеткова, and В. В. Бессонов. "Study of aromatic substances in the composition of a thermal technological flavor with a meat organoleptic profile using solid-phase microextraction with gas chromatography-mass spectrometry." Food processing industry, no. 3 (March 4, 2024): 9–13. http://dx.doi.org/10.52653/ppi.2024.3.3.002.
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В работе представлены результаты изучения душистых веществ в образцах ароматизаторов с мясным органолептическим профилем с добавлением источника серосодержащих веществ. В качестве дополнительного источника серосодержащих веществ рассмотрена возможность использования сухого порошка чеснока. В статье описан двухступенчатый процесс приготовления образцов ароматизатора с мясным органолептическим профилем. На первом этапе проводили культивирование дрожжей Sacchoromyces cerevisiae по общепринятой методике с целью получения предшественника ароматизатора, затем в предшественник ароматизатора вносили редуцирующий сахар и проводили синтез продуктов реакций Майяра при термической обработке смеси. Таким образом в результате проведенных операций получают технический термический ароматизатор. Первый образец был приготовлен по описанной методике, второй образец – аналогичным методом, с отличием в том, что перед нагревом смеси в нее вносили сухой молотый чеснок. Для исследования композиции душистых веществ использован метод твердофазной микроэкстрации с газовой хромато-масс-спектрометрией (ТФМЭ-ГЖХ-МС). Применяли волокно для твердофазной микроэкстракции с комбинированным покрытием дивинилбензол/карбоксен/полидиметилсилоксан 50/30 мкм (Supelco), газовый хроматограф Agilent Technologies 7890 A с хроматографической колонкой Supelcowax 10 60 м•0,53 мм•1 мкм (Supelco), пламенно-ионизационным детектором и масс-детектором Agilent Technologies 7000 B. Для получения значений индексов удерживания на неполярной колонке анализ проводили с использованием колонки HP-5MS 30 м•0,25 мм•0,25 мкм (Agilent Technologies). По результатам исследования идентифицировано 70 соединений с концентрациями от 0,2 до 965,3 мкг/кг (в пересчёте на внутренний стандарт нонанон-5). Большая часть обнаруженных соединений относилась к следующим группам: альдегиды, сложные эфиры, кетоны, спирты, серосодержащие соединения, азотсодержащие соединения, производные фурана, органические кислоты и отдельные представители других групп. Сравнительная оценка содержания душистых веществ, придающих мясной аромат, в органолептических профилях жареной говядины и разработанных образцов ароматизаторов свидетельствует об их близости. Установлено, что внесение сухого порошка чеснока благоприятно повлияло на органолептический профиль мясного ароматизатора. The paper presents the results of a study of fragrant substances in samples of flavorings with a meat organoleptic profile with the addition of a source of sulfur-containing substances. The possibility of using dry garlic powder was considered as an additional source of sulfur-containing substances. The article describes a two-step process for preparing flavor samples with a meat organoleptic profile. At the first stage, the Sacchoromyces cerevisiae yeast was cultivated according to the generally accepted method in order to obtain a flavor precursor, then reducing sugar was added to the flavoring precursor and the products of Maillard reactions were synthesized during heat treatment of the mixture. Thus, as a result of the operations performed, a technical thermal flavor is obtained. The first sample was prepared according to the described method, the second sample was prepared using a similar method, with the difference that before heating the mixture, dry garlic powder was added to it. The method of solid-phase microextraction with gas chromatography-mass spectrometry (SPME-GLC-MS) was used to study the composition of fragrant substances. We used solid-phase microextraction fiber with a combined coating of divinylbenzene/carboxen/polydimethylsiloxane 50/30 μm (Supelco), an Agilent Technologies 7890 A gas chromatograph with a Supelcowax 10 60 m•0.53 mm•1 μm chromatography column (Supelco), and a flame ionization detector and an Agilent Technologies 7000 B mass detector. To obtain retention indices on a non-polar column, analysis was performed using an HP-5MS 30 m•0.25 mm•0.25 μm column (Agilent Technologies). Based on the results of the study, 70 compounds were identified with concentrations ranging from 0.2 to 965.3 μg/kg (in terms of the internal standard nonanone-5). Most of the detected compounds belonged to the following groups: aldehydes, esters, ketones, alcohols, sulfur-containing compounds, nitrogen-containing compounds, furan derivatives, organic acids and individual representatives of other groups. A comparative assessment of the content of fragrant substances that impart meat aroma in the organoleptic profiles of fried beef and the developed samples of flavorings indicates their similarity. It was found that the addition of dry garlic powder had a beneficial effect on the organoleptic profile of meat flavoring.
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Labrath, Y. P. "Hydrotropic Extraction for Process Intensification in Delignification of Dried Jackfruit (Artocarpus heterophyllus) Leaves." International Journal of Biochemistry Research & Review 34, no. 3 (2025): 67–81. https://doi.org/10.9734/ijbcrr/2025/v34i3986.
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Background: The extraction of lignin is costliest, challenging process and is significant for production of various starting material useful in chemical synthesis, fuel production, weakening of cell wall to assists the extraction of natural active constituents from plants, in solid waste management and delignification assists in breaking of strong bonds of lignin and hemicellulose which entraps the fermentable cellulose. There is huge dried leaf waste, which has lignin component suitable for various applications. Further, the available lignin extraction methods affect the quality of lignin. Aim: The present study aimed to investigate the delignification of dried jackfruit tree foliage using aqueous hydrotropic solutions. Methods: The parameters studied for the delignification of dried jackfruit tree foliage include temperature, hydrotrope concentration dried leaves loading and delignification time. The obtained lignin is characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), UV-visible spectroscopy, and the ethanol extract of lignin is characterized by Gas chromatography-mass spectroscopy (GC-MS), gel permeation chromatography (GPC) correspondingly to understand in factors including the surface functionality, nature and morphology, molecular weight, phenolic compounds, thermal stability. Results: The hydrotrope NaXS at 30 % w/w concentration, extraction temperature of 100 0C, 5 % w/w foliage loading concentration were optimum. The process enabled 81 % of lignin extraction and 95 % of hydrotrope recovery. The lignins recovered from different aqueous hydrotrope solutions of Na-XS, and Na-CS, were apparently similar indicating similar nature of the lignin extracted by different hydrotropes. Sodium xylene sulfonate was most satisfactory amongst different hydrotropes for the delignification, the lignin could be recovered simply by water dilution and no solvent was used in any step. Reusability of hydrotrope was around 95 % for foliage delignification. Conclusion: The obtained lignin is free of organic solvents. The method selectively extracts lignin and keeps the cellulosic material intact as observed in conventional delignification processes.
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Tanaka, Yasuyuki. "Recent Advances in Structural Characterization of Elastomers." Rubber Chemistry and Technology 64, no. 3 (1991): 325–85. http://dx.doi.org/10.5254/1.3538561.
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Abstract One of the main targets of the structural characterization of elastomers so far has been the correlation of the polymerization conditions with the properties of the resulting polymers. The first step is the analysis of polymer structure, such as the chemical composition of copolymers, isomeric structure of diene polymers, degree of branching, extent of modification, functionality of end groups, amounts of abnormal groups, tacticity, and so on. Progress in nuclear magnetic resonance spectroscopy (NMR) makes possible the second step, which is the structural characterization of polymer chains, such as the sequence distribution of comonomer units in copolymer, isomeric units in diene polymers, configurational sequences in vinyl polymers, head and tail arrangement of monomer units. Recent development of FT-NMR spectroscopy, high-field spectroscopy from 300 MHz to 600 MHz at 1H-NMR, solid-state 13C-NMR, and two-dimensional NMR has facilitated a more detailed analysis of these structural features. The complexity of the structure of elastomers, which is derived from highly controlled copolymerization processes, leads to the widespread application of modern FT-NMR spectroscopy. It may reasonably be said that a fair number of structural problems in elastomers has been solved by NMR analysis. The high sensitivity of Fourier-transform infrared spectroscopy (FT-IR) has enabled one to determine trace structural changes in elastomers. Coupled on-line techniques such as gas-chromatography-mass-spectrometry combined with pyrolysis, liquid chromatography-NMR, and gel permeation chromatography-FT-IR will be powerful tools for the characterization of elastomers. Progress in analytical instruments has stimulated the development of high-performance elastomers, the synthesis of new speciality elastomers, and the elucidation of mechanisms for property enhancements. The use of modern instruments and a combination of ordinary methods of structural analysis have satisfied needs to some extent. However, a newer method of structural characterization is always desired in order to achieve higher orders of information. for example, the characterization of inhomogeneity along the polymer chain and between the polymer chains has become an important problem, especially in polymer blend systems. As to the former problem, spectroscopic methods provide only limited information. Although the NMR and FT-IR spectroscopies are very powerful tools for the analysis of short sequence distributions, it is difficult to characterize the distribution of long sequences and hybrid systems containing random and blocked sequences along the polymer chain. Gel permeation chromatography (GPC) is one of the most popular techniques for the analysis of molecular-weight distribution. However, it provides complicated information including molecular-weight distribution and chemical-composition distribution in the case of copolymers. Recent progress of high-performance liquid chromatography (HPLC) has provided a new powerful tool for the structural characterization of copolymers. It is appropriate to review the recent advances in structural characterization of elastomers, especially the characterization of microstructure of polymer chains, from the viewpoints of methodology and applicability of new methods. As to the NMR analysis of elastomers, reviews are available. Here, considerable attention is focused on the procedures for the assignment of signals, because the applicability of a NMR method is based on the reliability of the signal assignments. The other topics are selected to provide direct information for polymer synthesis or polymer properties.
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El-Wahed, Aida A. Abd, Eman H. Rashwan, Mohamed F. AlAjmi, et al. "Sidr Honeys Physical and Chemical Characterization, a Comprehensive Approach through LC-MS/MS, NMR, and GC-MS Analysis." Separations 10, no. 7 (2023): 372. http://dx.doi.org/10.3390/separations10070372.
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Honey intake is advantageous to human health due to its antioxidant, anticancer, anti-inflammatory, and antimicrobial properties, all of which are attributed to the rich bioactive compound contents. Moreover, hepatoprotective, wound healing, and gastrointestinal protective properties have been documented. Honey’s nutritional value is significantly affected by its chemical composition, which varies depending on botanical and geographical origin. In particular, after Manuka honey, Sidr honey from the Ziziphus species is the most popular. The chemical compositions, physicochemical properties, bioactive compounds, and sensory characteristics of two Sidr honey samples from Egypt and Saudi Arabia were investigated in the current study. Moisture content, electrical conductivity (EC), pH, free acidity (FA), total acidity, lactone hydroxymethylfurfural (HMF) content, and diastase (α-amylase) activity were measured. By using high-performance liquid chromatography (HPLC), mass spectrometry (LC-MS/MS), nuclear magnetic resonance (1HNMR), and solid-phase micro-extraction (SPME) coupled with gas chromatography (GC-MS) analyses, the sugar profile, non-volatile, and volatile compounds were also identified. The physicochemical analysis revealed the following results for Sidr honey from Saudi Arabia and Egypt, respectively: a moisture content of 18.03 ± 0.05% and 19.03 ± 0.06%, EC values of 1.18 ± 0.05 and 1.16 ± 0.01 mS/cm, pH values of 4.87 ± 0.08 and 5.10 ± 0.01, FA of 37.50 ± 0.05 and 36.50 ± 0.05 meq/kg, total acidity of 41.06 ± 0.05 and 37.50 ± 0.05 meq/kg, lactone of 3.49 ± 0.005 and 1 ± 0.0 meq/kg, HMF of 20.92 ± 0.02 and 11.33 ± 0.01 mg/kg, and diastase of 59.97 ± 0.05 and 8.64 ± 0.06g/100 g. Honey from Saudi Arabia and Egypt displayed 22.51 ± 0.05 and 26.62 ± 0.16 % glucose, 40.33 ± 0.06 and 35.28 ± 0.01% fructose, 8.94 ± 0.17, and 8.87 ± 0.01% sucrose, and 8.22 ± 0.006 and 8.13 ± 0.01% maltose, respectively. According to the International Honey Commission (IHC) and GCC Standardization Organization (GSO) regulations, the levels of glucose, fructose, sucrose, and maltose were near the standard levels. Flavonoids, sugars, vitamins, and nitrogen contents were additionally measured using LC-MS/MS, whereas GC-MS was employed to identify aldehydes, ketones, phenols, acids, esters, anthraquinone, hydrocarbons, and nitrogenous compounds. The results of a study on the effect of honey’s geographic origin on its broad quality are summarized. As a result, knowing its optimal chemical and physical characteristics served as the criterion and indicator of the honey’s quality.
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"GAS SOLID CHROMATOGRAPHY, GSC." A-to-Z Guide to Thermodynamics, Heat and Mass Transfer, and Fluids Engineering g (2006). http://dx.doi.org/10.1615/atoz.g.gassolchrgsc.
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Saranya, T. J* V.M Nishad Prasobh G. R. "GAS CHROMATOGRAPHY." June 6, 2023. https://doi.org/10.5281/zenodo.8010662.
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<em>Gas chromatography (GC) is a common type of chromatography used in analytical chemistry for separating and analyzing compound that can be vaporized without decomposition. The principle of separation in GC is “<strong>partition</strong>”. There are mainly 2two type of chromatography Gas solid chromatography (GSC), Gas liquid chromatography(GLC).Gas chromatography have pharmaceutical applications like quality control and analysis of drug products such as antibiotics, anti-virals, general anesthetic, sedatives etc.It is also used for determining purity of compound. The present review summarizes the instrumentation, validation methods and applications of gas chromatography.</em> <em>Keyword ; Chromatography, Stationary Phase, Mobile Phase, Absorption, Partition</em>
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Kirtimaya, Mishra* Dr. K. Balamurugan1 Dr. R. Suresh1. "A REVIEW: AN APPROACH TOWARDS THE ANALYTICAL METHOD DEVELOPMENT FOR DETERMINATION OF NEWER DRUGS." January 31, 2017. https://doi.org/10.5281/zenodo.2349293.
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In this present scenario for treating various diseases several new drugs were invented. Before launching to the market these drugs must undergo analytical validation process. In this review some of analytical techniques such as ultraviolet/ visible spectrophotometry, fluorimetry, capillary electrophoresis, and chromatographic methods (gas chromatography and high-performance liquid chromatography), LC-MS, GC-MS, SOLID PHASE EXTRACTION, NMR, MASS Spectrophotometry LC/MS/MS LC/UV X-ray crystallography were discussed.
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Bondoc, Jonah, Lemnuel Aragones, and Charita Kwan. "Development, Validation, and Application of a Three-way Cleanup Method for GC/MS Measurement of PCBs in Stranded Cetaceans in Philippine Waters." Philippine Journal of Science 150, no. 5 (2021). http://dx.doi.org/10.56899/150.05.19.
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Polychlorinated biphenyls (PCBs) are a group of synthetic organic chemicals that enrich the food chain via biomagnification where the highest levels have been detected in cetaceans. While several studies have reported cetaceans as sentinels of environmental pollution, information on the contamination status of PCBs in cetaceans found stranded along Philippine coasts has been very limited over the past decades. An important contributory factor to this paucity is the challenging analytical method for the analysis of PCBs in lipid-rich biological tissues due to lipid interferences that can affect gas chromatographic systems especially column efficiency and lifetime. Thus, a modified method consisting of a series of three cleanup steps – involving isolation column chromatography, gel permeation chromatography (GPC), and solid-phase extraction (SPE) using silica gel following Soxhlet extraction, plus macro- and micro-concentration prior to gas chromatographic/mass spectrometric analyses – was used. Recovery of added analytes corresponding to appropriate concentration ranges and repeatability of data values were excellent as values obtained were within the established performance criteria of 40–120% recovery, including a 106% mean recovery for the QC material (FAPAS T05100QC – Oily Fish) and < 30% RSD for an analyte concentration of 1 µg kg–1. Thus, the modified cleanup technique in conjunction with GC/MS detection is proven suitable for its intended use. Thirtyeight (38) congeners (PCBs-8, -12, -19, -18, -33, -38, -35, -37, -52, -44, -57, -74, -79, -78, -81, -77, -104, -99, -123, -118, -114, -126, -155, -153, -162, -167, -156, -157, -169, -188, -189, -202, -195, -194, -205, -208, -206, and -209) were detected in cetacean blubber (n = 15) ranging from 21.7 ng g–1 lipid weight (in an adult female dwarf sperm whale (Kogia sima) found in Camarines Sur) to 1460 ng g–1 lipid weight (in an adult male rough-toothed dolphin (Steno bredanensis) found in Zambales.
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Azeez, Mayowa A. "Brisk Method for Fractionating and Separating Bio-Crude Oil." International Research Journal of Pure and Applied Chemistry, May 13, 2019, 1–9. http://dx.doi.org/10.9734/irjpac/2019/v18i430097.
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A new approach for the analysis of bio-crude oils (BCOs) has been qualitatively explored. The analytical scheme is based on the fractionation of BCO through precipitation in water, freeze-drying, solid phase extraction (SPE) and combinations of analytical techniques for the analysis of fractions. Monomeric components in BCO were characterised using gas chromatography coupled with mass spectrometer and flame ionisation detector (GC-MS/FID). The molecular mass distribution of oligomers was determined using gel permeation chromatography (GPC). The fractionation procedure appeared to have succeeded to a large extent as evident in the detection of various components along their expected fraction in the GC-MS/FID analysis. However, a quantitative analysis of the multiple components in different fractions appeared difficult owing to the loss of many volatile fractions through the fractionation procedure. And less than 7 wt. % of the sugar-related components in the acetylated polar SPE fraction were identified.
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Miroshnikova, Angelina V., Sergey V. Baryshnikov, and Yuriy N. Malyar. "Depolymerization of Pine Ethanol Lignin in the Medium of Supercritical Ethanol in the Presence of Catalysts NiCu/SiO₂ and NiCuMo/SiO₂." Journal of Siberian Federal University. Chemistry, June 2020, 247–59. http://dx.doi.org/10.17516/1998-2836-0179.
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The regularities of thermocatalytic transformation of pine ethanol lignin in supercritical ethanol in the presence of catalysts NiCu/SiO₂ and NiCuMo/SiO2 in the temperature range 250–400 °C were established. The composition and structure of ethanol lignin, liquid and solid products of its conversion were studied by methods of elemental analysis and gel-permeating chromatography (GPC). The composition of gaseous products – by method of gas chromatography. At the process temperature of 250 °C the catalysts do not have a significant effect on conversion of ethanol lignin. The maximal yield of liquid products (83.5 wt. %) was obtained at temperature 300 °C in the presence of catalyst NiCuMo/SiO₂ containing 8.8 wt. % of molybdenum. At temperature 350 °C NiCu/SiO₂ and NiCuMo/SiO2 catalysts contribute to the almost complete conversion of ethanol lignin into liquid and gaseous products, and the yield of solid products does not exceed 1 wt. %. In liquid products of catalytic conversion there is a decrease in the atomic ratio of O/C and the increase of H/C atomic ratio as compared to initial ethanol lignin due to catalytic intensification of reactions of deoxygenation and hydrogenation of lignin and products of its depolymerization. According to GPC data on the curves of molecular mass distribution (MMD) of liquid products of thermocatalytic conversion of ethanol lignin at 300 °C there are peaks with highs at 160 and 380 Da, probably related to guiacyle monomers and dimmers, respectively. From the comparison of MMD of liquid products obtained by ethanol lignin depolymerization at 300 °C over catalysts NiCu/SiO₂ and NiCuMo/SiO₂ it follows, that the introduction of molybdenum in the catalyst promotes the formation of monomeric guaiacyl products
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K., Mohammed, Agarwal M., Mewman J., and Ren Y. "Optimization and Validation for Determination of VOCs from Lime Fruit Citrus aurantifolia (Christm.) with and without California Red Scale Aonidiella aurantii (Maskell) Infested by Using HS-SPME-GC-FID/MS." September 1, 2017. https://doi.org/10.5281/zenodo.1132707.
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An optimum technic has been developed for extracting volatile organic compounds which contribute to the aroma of lime fruit (<em>Citrus aurantifolia</em>). The volatile organic compounds of healthy and infested lime fruit with California red scale <em>Aonidiella</em> <em>aurantii</em> were characterized using headspace solid phase microextraction (HS-SPME) combined with gas chromatography (GC) coupled flame ionization detection (FID) and gas chromatography with mass spectrometry (GC-MS) as a very simple, efficient and nondestructive extraction method. A three-phase 50/30 μm PDV/DVB/CAR fibre was used for the extraction process. The optimal sealing and fibre exposure time for volatiles reaching equilibrium from whole lime fruit in the headspace of the chamber was 16 and 4 hours respectively. 5 min was selected as desorption time of the three-phase fibre. Herbivorous activity induces indirect plant defenses, as the emission of herbivorous-induced plant volatiles (HIPVs), which could be used by natural enemies for host location. GC-MS analysis showed qualitative differences among volatiles emitted by infested and healthy lime fruit. The GC-MS analysis allowed the initial identification of 18 compounds, with similarities higher than 85%, in accordance with the NIST mass spectral library. One of these were increased by <em>A. aurantii</em> infestation, D-limonene, and three were decreased, Undecane, α-Farnesene and 7-epi-α-selinene. From an applied point of view, the application of the above-mentioned VOCs may help boost the efficiency of biocontrol programs and natural enemies’ production techniques.
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Wilson, Liza A., Fabien Deligey, Tuo Wang, and Daniel J. Cosgrove. "Saccharide analysis of onion outer epidermal walls." Biotechnology for Biofuels 14, no. 1 (2021). http://dx.doi.org/10.1186/s13068-021-01923-z.
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Abstract Background Epidermal cell walls have special structural and biological roles in the life of the plant. Typically they are multi-ply structures encrusted with waxes and cutin which protect the plant from dehydration and pathogen attack. These characteristics may also reduce chemical and enzymatic deconstruction of the wall for sugar analysis and conversion to biofuels. We have assessed the saccharide composition of the outer epidermal wall of onion scales with different analytical methods. This wall is a particularly useful model for cell wall imaging and mechanics. Results Epidermal walls were depolymerized by acidic methanolysis combined with 2M trifluoracetic acid hydrolysis and the resultant sugars were analyzed by high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD). Total sugar yields based on wall dry weight were low (53%). Removal of waxes with chloroform increased the sugar yields to 73% and enzymatic digestion did not improve these yields. Analysis by gas chromatography/mass spectrometry (GC/MS) of per-O-trimethylsilyl (TMS) derivatives of the sugar methyl glycosides produced by acidic methanolysis gave a high yield for galacturonic acid (GalA) but glucose (Glc) was severely reduced. In a complementary fashion, GC/MS analysis of methyl alditols produced by permethylation gave substantial yields for glucose and other neutral sugars, but GalA was severely reduced. Analysis of the walls by 13C solid-state NMR confirmed and extended these results and revealed 15% lipid content after chloroform extraction (potentially cutin and unextractable waxes). Conclusions Although exact values vary with the analytical method, our best estimate is that polysaccharide in the outer epidermal wall of onion scales is comprised of homogalacturonan (~ 50%), cellulose (~ 20%), galactan (~ 10%), xyloglucan (~ 10%) and smaller amounts of other polysaccharides. Low yields of specific monosaccharides by some methods may be exaggerated in epidermal walls impregnated with waxes and cutin and call for cautious interpretation of the results.