Linear Retention Indices Research Articles

Minor constituents of essential oils and aromatic extracts. Oximes derived from natural flavor and fragrance raw materials – Sensory evaluation, spectral and gas chromatographic characteristics

A small library of 57 low molecular weight oximes was prepared from fragrant aldehydes and ketones, and their olfactory profiles were determined. The most substantive and interesting in terms of the sensory impressions were (+)-isomenthone oxime (fresh, musty, green) and cyclocitral oxime (earthy with patchouli, moss and leather notes). The linear retention indices (LRI) were determined for DB-1, DB-5 and DB-WAX columns, and E/Z isomers of 22 out of 57 compounds were resolved on the DB-5 column. Attempts were made to resolve enantiomers of the chosen oximes on chiral GC columns. The best results were obtained by using a Cyclosil B column, on which the enantiomers of camphor, menthone, piperitone and carvone oximes were fully resolved. NMR and MS spectra were acquired to characterize the synthesized library. Gas chromatography–olfactometry was used to assess odoriferous properties of both isomers of oximes. In most cases both isomers possessed similar profile and intensity.

Oxygen heterocyclic compound screening in Citrus essential oils by linear retention index approach applied to liquid chromatography coupled to photodiode array detector

AbstractTo date, liquid chromatography coupled to a photodiode array (PDA) detector is the main technique employed to analyse furocoumarins (FCs) in essential oils. This type of detection may lead to poor performance because of the low sensitivity and selectivity of PDA detection. In this work, the linear retention index (LRI) was used in combination with a UV‐Vis library for the identification of 35 oxygen heterocyclic compounds in Citrus essential oils, making it possible to distinguish compounds with very similar spectra. As opposed to retention time, which can significantly change with the instrument or laboratory used, LRI represents a kind of normalized relative retention time, as independent as possible from operating conditions. From a qualitative point of view, reproducibility results are provided to definitively assess the suitability of such an approach for inter‐laboratory use and for a fully automated process, even when pure and very expensive standard materials are not available, as just the LRI database and the UV‐Vis library are needed. From a quantitative point of view, calibration curves were created in pure solvent and by adding standard compounds to several blank matrices, with the aim of evaluating differences, overcoming matrix effects, achieving the correct limits of quantification, and providing the quantitative profile of real samples. The LRI system is not listed in the Commission Decision 2002/657/EC as criteria for the Full Scan UV‐Vis detection; however, its validity and applicability are here investigated and proposed for future applications, in combination with the UV‐Vis library.

Non-targeted analysis of the particulate phase of heated tobacco product aerosol and cigarette mainstream tobacco smoke by thermal desorption comprehensive two-dimensional gas chromatography with dual flame ionisation and mass spectrometric detection

An analytical methodology based on thermal desorption and comprehensive two-dimensional gas chromatography with dual time-of-flight mass spectrometry and flame ionization detection (TD-GC × GC-TOFMS/FID) has been developed for non-target analysis of volatile organic compounds (VOCs). The technique was optimised for the measurement of the VOC content of the particulate phase (PP) fraction of aerosols produced by a tobacco heating product (THP1.0) and 3R4F mainstream tobacco smoke (MTS). The method involves sampling the PP fraction on quartz wool packed in a sorbent tube directly connected to machine-puffing, followed by a dilution through a TD recollection procedure over Tenax/Sulficarb sorbent before TD-GC × GC-TOFMS/FID analysis. The comparison of the VOC content of the PP fraction of aerosols produced by THP1.0 and MTS highlighted the compositional difference between tobacco combustion (592 peaks) and tobacco heating process (160 peaks). Mass spectrometric signals were used for qualitative analyses based on linear retention indices, mass spectral matches, and GC × GC structured chromatograms, which collectively identified up to 90% of analytes detected in PP samples. FID signals were used for semi-quantitative analyses based on a chemical class external calibration method. The global chemical composition of PP samples showed that hydrocarbons, oxygenated, and nitrogen-containing compounds were fewer in number and much less abundant in THP1.0 PP. Overall, 93 compounds were common to the two sample types. Excepted for a few highly volatile compounds (mainly furan family) as well as glycerine and its acetate, analyte concentrations were higher in MTS PP.

Volatolomics approach by HS-SPME-GC-MS and multivariate analysis to discriminate olive tree varieties infected by Xylella fastidiosa.

Xylella fastidiosa (Xf) is a pathogenic bacterium that causes diseases in olive trees. Therefore, analytical methods for both the characterisation of the host/pathogen interaction and infection monitoring are needed. Volatile organic compounds (VOCs) are emitted by plants relate to their physiological state, therefore VOCs monitoring can assist in detecting stress or infection states before visible signs are present. In this work, the headspace-solid phase microextraction-gaschromatography-mass spectrometry (HS-SPME-GC-MS) technique was used for the first time to highlight VOCs differences between healthy and Xf-infected olive trees. VOCs from olive tree twig samples were extracted and analysed by HS-SPME-GC-MS, and hence identified by comparing the experimental linear retention indexes with the reference values and by MS data obtained from NIST library. Data were processed by principal component analysis (PCA) and analysis of variance (ANOVA). The HS-SPME step was optimised in terms of adsorbent phase and extraction time. HS-SPME-GC-MS technique was applied to the extraction and analysis of VOCs of healthy and Xf-infected olive trees. More than 100 compounds were identified and the differences between samples were evidenced by the multivariate analysis approach. The results showed the marked presence of methyl esters in Xf-infected samples, suggesting their probable involvement in the mechanism of diffusible signal factor. The proposed approach represents an easy and solvent-free method to evaluate the presence of Xf in olive trees, and to evidence volatiles produced by host/pathogen interactions that could be involved in the defensive mechanism of the olive tree and/or in the infective action of Xf.

COMPONENT COMPOSITION OF ESSENTIAL OIL OF PINE BUDS (PINUS SYLVESTRIS L.), GROWING IN THE URBAN ENVIRONMENT OF TOMSK REGION

The component composition of pine buds essential oil, growing in the area of active economic activity in Tomsk region, has been studied. Essential oil from pine buds obtained by the method of distillation with the water steam.
 The component composition of the essential oil was studied by gas-liquid-chromatography-mass spectrometry on the gas chromatograph Agilent 6890 with quadrupole mass spectrometer (HP MSD 5973N). Chromatography conditions: 30-meter long quartz column HP-5MS with internal diameter 0.25 mm, film thickness of 0.25 µm (copolymer 5% diphenyl 95% dimethylsiloxane), carrier gas – helium (constant flow 1 ml/min), column temperature – 50 °С (2 min isotherm), 50–200 °С (40 °C, min), 200–280 °С (20 °С/min), 280 °С (5 min isotherm), the temperature of the ion source 170 °С, the interface between the gas chromatograph and mass selective detector 280 °С. The energy of ionizing electrons is 70 eV. The volume of injected sample of 1 µl. The component composition was determined by comparing the times and linear retention indices, mass spectra values, the database of the chromatographic-mass spectrometric library of volatile substances of plant origin. About 163 individual components were found. It is established that with the increase of technogenic pollution, the amount of essential oil decreases, the component composition changes, which can serve as an indicator of the quality of raw materials, the state of the forest stand of pine and the environment as a whole.
 Data on the dominant content of 3-caren in the composition of essential oils of the pine buds, growing in the Tomsk region, suggests a limited use of this raw material and essential oil on its basis in medical practice.

STUDYING THE CHEMICAL COMPOSITION OF ESSENTIAL OIL RECEIVED FROM FRUITS OF PRANGOS ODON-TALGICA WILD-GROWING IN ASTRAKHAN REGION

The chemical composition of Prangos odontalgica (Pall.) Herrnst. et. Heyn essential oil, which grows wild in the Astrakhan region, has not been practically studied, unlike other species of the genus Prangos, growing in Iran, Turkey and Uzbekistan. To obtain the essential oil, all parts of the plant (roots, stems, flowers, leaves, fruits) are used, as well as various methods of isolation (hydrodistillation, supercritical fluid extraction, solid-phase microextraction, and others). Essential oil from the fruit of Prangos odontalgica we obtained by the method of hydrodistillation. The duration of the hydrodistillation process, established experimentally on the basis of a study of the dynamics of change in the yield of essential oil over time, was 3 hours. The yield of essential oil in mass% by volume in terms of absolutely dry raw materials according to the results of a threefold determination is 0.07 ± 0.01%. The method of gas-liquid chromatography carried out a quantitative analysis of the main components of the essential oil Prangos odontalgica. The quantitative content of the components of the essential oil was calculated by the areas of gas chromatographic peaks without the use of correction factors. Qualitative analysis was performed by comparing linear retention indices. In the Prangos odontalgica essential oil, 38 substances were identified (88.4%). It contains sesquiterpenes (31.48%), terpenoids (19.2%), hydrocarbons (15.39%), carboxylic acids and their esters (10.86%), alcohols, phenols (8.84%). Among sesquiterpenes, the predominant components are γ-elemen (9.84%), bisabolol (9.41%), and among terpenoids – trans-nerolidol (3.90%) and linalyl isobutyrate (3.41%).

Odor-contributing volatile compounds of wild edible Nordic mushrooms analyzed with HS–SPME–GC–MS and HS–SPME–GC–O/FID

Although Nordic wild edible mushrooms offer a wide range of different odors their scientific examination has been scarce. The aim of this study was to characterize the aroma compounds of four Finnish wild mushroom species with trained assessors using gas chromatography–olfactometry as well as gas chromatography–mass spectrometry. Headspace volatiles were extracted from sous vide cooked mushroom samples (Boletus edulis, Lactarius camphoratus, Cantharellus cibarius and Craterellus tubaeformis) using solid-phase microextraction. Odor-contributing compounds were measured with two columns of differing polarity using the detection frequency method. Compounds were identified based on reference compounds, linear retention indices, odor descriptions, and mass spectrometry. Both the volatile compound profiles and the aromagrams were distinct with characteristic compounds for each species. The results demonstrate that especially saturated and unsaturated aldehydes and ketones contribute to the odor of the studied wild mushrooms. This thorough comparison also indicates compounds linked to the sensory properties of mushrooms.

Composition of Essential Oils from <i>Litsea acutivena</i> Hayata

The chemical components of the leaf oil of Litsea acutivena Hayata collected from Pù Huong Natural Reserve, Nghe An Province, Vietnam, were identified by co-chromatography with authentic samples, gas chromatography/mass spectrometry (GC/MS) and linear retention indices. The significant compounds of L. acutivena were α-phellandrene (30.4%) and α-pinene (14.2%). The constituents of essential oil of L. acutivena from Vietnam are being reported for the first time.

An alarm pheromone in the venom gland of Vespa velutina: evidence revisited from the european invasive population

Alarm pheromones are major communication signals in animals and major semiochemicals in the colony organisation of social insects. We investigated the composition of venom in Vespa velutina, an invasive hornet species accidentally introduced into Europe a decade ago. Crushed venom glands were applied to seven wild V. velutina nests and induced aggressive responses of workers in all the colonies tested. Then, solvent extracts or headspace Solid Phase Micro Extraction (SPME) were analysed and quantified by gas chromatography coupled with either flame ionization detector or a mass spectrometer, and checked retention times to Kovats indices and Linear retention indices (LRI). We compared our results to those obtained in the same species from its native area in a previous study. Nonan-2-one and the 4, 8-dimethylnon-7-en-2-one were found in large amount in the venom gland. Five other molecules including the heptan-2-one, non-8-en-2-one, undecan-2-one and two unknown molecules were also found. Similar compounds were globally found, however, one unknown compound was present in our European population but absent in native area ones and should be identify. Although pheromones are thought to be species-specific, our results suggest that their composition may vary within species due to population history, thus questioning its value as a taxonomic tool. Although our results are preliminary, we also recommend carefully considering the origin of the Vespa velutina individuals chosen to develop pheromone-based methods (attractants or mating disruption) for pest management.

Retention-time prediction in comprehensive two-dimensional gas chromatography to aid identification of unknown contaminants

Comprehensive two-dimensional (2D) gas chromatography (GC×GC) coupled to mass spectrometry (MS, GC×GC-MS), which enhances selectivity compared to GC-MS analysis, can be used for non-directed analysis (non-target screening) of environmental samples. Additional tools that aid in identifying unknown compounds are needed to handle the large amount of data generated. These tools include retention indices for characterizing relative retention of compounds and prediction of such. In this study, two quantitative structure–retention relationship (QSRR) approaches for prediction of retention times (1tR and 2tR) and indices (linear retention indices (LRIs) and a new polyethylene glycol–based retention index (PEG-2I)) in GC × GC were explored, and their predictive power compared. In the first method, molecular descriptors combined with partial least squares (PLS) analysis were used to predict times and indices. In the second method, the commercial software package ChromGenius (ACD/Labs), based on a “federation of local models,” was employed. Overall, the PLS approach exhibited better accuracy than the ChromGenius approach. Although average errors for the LRI prediction via ChromGenius were slightly lower, PLS was superior in all other cases. The average deviations between the predicted and the experimental value were 5% and 3% for the 1tR and LRI, and 5% and 12% for the 2tR and PEG-2I, respectively. These results are comparable to or better than those reported in previous studies. Finally, the developed model was successfully applied to an independent dataset and led to the discovery of 12 wrongly assigned compounds. The results of the present work represent the first-ever prediction of the PEG-2I.Graphical abstractᅟ

Comprehensive comparative compositional study of the vapour phase of cigarette mainstream tobacco smoke and tobacco heating product aerosol

A simple direct sample collection/dilution and introduction method was developed using quartz wool and Tenax/sulficarb sorbents for thermal desorption and comprehensive two-dimensional gas chromatography (TD-GC × GC) analyses of volatile organic compounds from vapour phase (VP) fractions of aerosol produced by tobacco heating products (THP1.0) and 3R4F mainstream tobacco smoke (MTS). Analyses were carried out using flame ionisation detection (FID) for semi-quantification and both low and high resolution time-of-flight mass spectrometry (LR/HR-TOFMS) for qualitative comparison and peak assignment. Qualitative analysis was carried out by combining identification data based on linear retention indices (LRIs) with a match window of ±10 index units, mass spectral forward and reverse library searches (from LR and HRTOFMS spectra) with a match factor threshold of >700 (both forward and reverse), and accurate mass values of ± 3 ppm for increased confidence in peak identification. Using this comprehensive approach of data mining, a total of 79 out of 85 compounds and a total of 198 out of 202 compounds were identified in THP1.0 aerosol and in 3R4F MTS, respectively. Among the identified analytes, a set of 35 compounds was found in both VP sample types. Semi-quantitative analyses were carried out using a chemical class-based external calibration method. Acyclic, alicyclic, aromatic hydrocarbons and ketones appeared to be prominent in 3R4F MTS VP, whereas larger amounts of aldehydes, ketones, heterocyclic hydrocarbons and esters were present in THP1.0 aerosol VP. The results demontsrate the capability and versatility of the method for the characterization and comparison of complex aerosol samples and highlighted the relative chemical simplicity of THP1.0 aerosol in comparison to MTS.

Monoacylglycerol and diacylglycerol production by hydrolysis of refined vegetable oil by-products using an immobilized lipase from Serratia sp. W3.

Unlike the synthetic surfactants, mono- and diacylglycerols have the advantage to be biodegradable and non-toxic. In the present work, the hydrolysis of lipid fraction by-products of refined vegetable oils was performed by Serratia sp. W3 lipase immobilized on CaCO3 by combined adsorption and precipitation. This support was selected out of four carriers as it exhibited the finest activity support (950U/g) and the most satisfactory behavior at use. The immobilized preparation with CaCO3 was stable and active in the whole range of pH (4 to 9) and temperature (37 to 55°C), yielding a 75% degree of hydrolysis at optimal environmental conditions of pH 8.5 and temperature 55°C. Thin-layer chromatography, gas chromatography, and liquid chromatography methods were evaluated to determine the analytical characterization of hydrolysis products. For monoacylglycerols and diacylglycerol fractions identified in the samples, a novel approach by liquid chromatography method was employed, through a homemade linear retention index database and a dedicated software. The adopted approach allowed the use of basic instrumentation set-ups, without the need of sophisticated detectors, such as mass spectrometers. Thus, it could be an effective alternative to produce emulsifiers from cheap vegetable oils.

QSRR Study of Linear Retention Indices for Volatile Compounds using Statistical Methods

QSRR Study of Linear Retention Indices for Volatile Compounds using Statistical Methods

Volatile aroma compounds in wines from Chinese wild/hybrid species

The volatile aroma compounds in wines produced from Chinese wild/hybrid species were investigated in comparison to wines from European grapes. Volatiles were extracted by headspace solid-phase micro-extraction and identified by gas-chromatography/mass-spectrometry. The identification of analyte was performed by a combination of the linear retention index approach with the comparison of the obtained mass spectra. A total of 98 peaks were tentatively assigned as wine aroma components, and 15 odorants can be found at concentrations above their odor threshold among the odor activity values (OAVs) of 46 compounds evaluated in all of the wines. The "OAVs' aroma wheels" showed that the classes of aromatic series are first fruity, next herbaceous and roasty and no spicy and caramelized notes. Via principal component analysis, all the grape germplasm studied could be divided into four groups: "Jingsheng-1," "Cabernet Gernischt," "Beibinghong," and others, which exhibited distinctive aroma features, respectively. Practical applications Chinese wild grape species have many desirable properties for wine grape breeding such as possessing strong resistant genes to fungal diseases and cold condition, especially after hybridization with European grapes. As an emerging wine country, wines from Chinese wild/hybrid species have achieved much success in the last few years. The chemical content and biological properties have been studied extensively in many but there are a few studies in our knowledge about the wine tastes of these species. In this paper, the key odorants in wines produced from the Chinese grape species of V. amurensis Rupr., V. davidii Foex., and V. quinquangularis Rehd. and its hybrids were characterized in comparison to wines produced from European grapes (V. vinifera). The findings will help to the further understanding of the key aroma components in the different Chinese grapevine germplasm, and make further efforts to enrich the wine types in the marketplace.

Generalization of Reference System for Calculating the Second Dimension Retention Index in GC × GC–MS

Using C4–C25 fatty acid methyl esters (C4–C25 FAMEs) as a sample reference series, a method was developed to generalize the reference system for calculating the second dimension retention index (2I) of compounds analyzed by comprehensive two-dimensional gas chromatography–mass spectrometry (GC × GC–MS). The second dimension elution temperature (2Te), second dimension unadjusted retention time (2tR), and the linear retention index (IT) of C4–C25 FAMEs were used to form a second dimension retention index surface (2IS) via a three-dimensional surface fitting model. The 2I of an analyte analyzed by GC × GC–MS was then calculated from the 2IS based on its 2tR and 2Te. The developed method was validated by calculating the 2I of n-alkanes, 80 compounds, and two commercially available mixtures (MegaMix A and MegaMix B). Compared to the conventional method, the developed method keeps the 2I in n-alkane retention index scale, and enables using any compounds as references to obtain a much increased separation space in the second dimension GC.

Volatile profile of soursop (Annona muricata L.) using HS-SPME-GC/MS

The aroma is one of the most appreciated sensorial attributes of fruit and one of the decisive factors in choosing a food. The flavor industry has grown significantly in recent years and the consumer's desire for new essences has given rise to the development of products from non-conventional fruits. The soursop (Annona muricata L.) is an important tropical fruit known to have a pleasant aroma and distinctive flavor. The objective of this work was to capture the volatiles from soursop pulp using solid phase microextraction (SPME) with the fibers 85 μm CAR/PDMS (carboxen/polydimethylsiloxane), 65 μm PDMS/DVB (polydimethylsiloxane/ divinylbenzene) and 50/30 μm DVB/CAR/PDMS (divinylbenzene/carboxen/ polydimethylsiloxane). The separation of volatile compounds was performed by GC-MS equipped with a nonpolar column (DB5-MS 30 m × 0.25 mm × 0,25 μm), and identified by comparing the mass spectra of the compounds of the samples with NIST (National Institute of Standards & Technology) and by comparison of the linear retention index (LRI). A total of 47 volatile compounds were identified with SPME technique, including 26 esters, 9 terpenes, 4 aldehydes, 1 alcohol, 2 aromatic hydrocarbons, 2 alkanes and 3 unidentified. Among the tested fiber which extracted more number of compounds was PDMS/DVB with a total of 39 compounds, and compounds with greater total area were the methyl hexanoate (39.19%), trans-2-methylhexanoate (25.23%), methyl butanoate (15.35%), trans-2-methyl-butenoate (4.41%) and trans-2-methyl octenoate (2.54%).

Proposal of a Linear Retention Index System for Improving Identification Reliability of Triacylglycerol Profiles in Lipid Samples by Liquid Chromatography Methods.

The retention index system was proposed in 1958 by Kováts. It is based on the correlation between the retention time of the analytes and the ones of a series of reference standards, making retention data dependent on the chromatographic phenomenon only, viz., on the three-term interaction analyte-stationary phase-mobile phase. Particularly in GC, because the mobile phase has a negligible influence, the retention of the analytes depends almost entirely on the stationary phase and it is as independent as possible from operating conditions. This makes retention index databases usable in samples identification at both the intra- and interlaboratory levels. The scope of this research was to create a similar identification system in LC, where the identification of unknowns is still a challenge because of the unavailability of spectral databases related to the low reproducibility of mass spectra generated by means of the atmospheric pressure ionization technique normally interfaced to LC. Lipid compounds, specifically triacylglycerols, were selected as target analytes mainly due to their regular chromatographic LC profile under reversed phase conditions. The odd carbon chain number triacylglycerol series from trinonain to trinonadecanoin was chosen as the basis of the retention index scale and a database of 209 triacylglycerols was built. For this purpose an ultra high-performance LC method, able to maximize the baseline separation of triacylglycerols in different real-world samples (vegetable oils, fish, and milk samples) was developed.

Use of solid phase microextraction to identify volatile organic compounds in brazilian wines from different grape varieties

Abstract The Brazilian wine industry has shown significant growth in recent years and the insertion of new concepts, such as geographical indications as signs of quality, has placed Brazil in tune with the tendencies of world wine production. The aim of this work was to apply the Solid Phase Microextraction technique in combination with Gas Chromatography-Mass Spectrometry to study Brazilian wines made from different grape varieties, in order to separate and identify their volatile organic compounds. These substances were identified by comparisons between the spectra obtained with those presented in the NIST library database, and by comparisons with linear retention indices and literature data. The amounts of the compounds were calculated based on the total peak areas of the chromatograms. Forty-seven volatile compounds were identified and grouped into alcohols, aldehydes, fatty acids, esters, hydrocarbons, ketones and terpenes. Most of them belonged to the ester function, conferring a fruity aroma on the wines. The alcohols may have originated from the yeast metabolism, contributing to the alcoholic and floral aromas. Ethyl lactate, 1-hexanol and diethyl maleate were identified in all the varieties, except Merlot. Decanal, methyl citronellate, (E)-2-hexenyl-3-methylbutyrate were only found in Merlot, while 2,3-butanediol was only present in the Tannat wines. 2-Phenylethanol was present in all varieties and is recognized as giving pleasant rose and honey attributes to wines. This study showed that the volatile profile of red wines is mainly characterized by esters and higher alcohols. The statistical analysis of the comparison of averages showed a greater amount of averages significantly different in the relative areas of Merlot wine. The Principal Component Analysis showed one grouping composed only of the Merlot wine samples, and this was probably related to the existence of the volatile organic compounds that were specifically identified in these wines.

Valorization of coffee silverskin industrial waste by pyrolysis: From optimization of bio-oil production to chemical characterization by GC × GC/qMS

Coffee bean tegument (silverskin) is a by-product derived from the coffee roasting process. This residue has been discarded, which constitutes a serious environmental problem. The depletion of oil reserves and environmental issues promoted by the combustion of fossil fuels has generated interest in the use of biomass to obtain fuel and chemicals products. The liquid product obtained by biomass pyrolysis is commonly called bio-oil. Bio-oil is a complex mixture of compounds, and its detailed chemical characterization is necessary to prospect its potential uses. Therefore, this study optimized the final temperature of pyrolysis and N2 flow rate parameters for the pyrolysis of silverskin in a fixed bed reactor, by using a central composite design and response surface. The bio-oil chemical composition was evaluated by comprehensive two-dimensional gas chromatography coupled to rapid-scanning quadrupole mass spectrometry (GC × GC/qMS), combined with the use of standards and linear temperature-programmed retention indices (LTPRI). The optimal values ​​calculated were 560 °C for the final pyrolysis temperature and 49 mL min−1 for the N2 flow rate. The organic phase yield was 15.2% under these conditions. At the optimal conditions, 228 compounds were identified (90.1% of the sample chromatographic volume) in the organic phase. The major chemical class, in terms of volume percentage, were the phenols (26.70%), followed by nitrogen compounds (18.51%). In addition, it is worth mentioning the high representability of the saturated hydrocarbons (8.28%), unsaturated aliphatic (6.69%), and aromatics (7.77%), which together account for 22.74% of the sample chromatographic volume. These results showed that the silverskin bio-oil may have the potential use as a source of chemical inputs.

STUDY OF CHEMICAL COMPOSITION OF TAMARIX RAMOSISSIMA ESSENTIAL OIL

Samples of essential oil from Tamarix ramosissima plant growing in the Astrakhan region were obtained by steam distillation and the dependence of its yield on the vegetative period of the plant was studied. The duration of the process of steam distillation was established experimentally on the basis of a study of the dynamics of the change in the yield of essential oil in time. The yield of essential oil was determined in % by weight of absolutely dry raw material. The largest yield of essential oil was obtained from plants in the flowering phase (0,23–0,3%). By method of gas-liquid chromatography carried out a quantitative analysis of the main components of essential oil Tamarix ramosissima. The quantitative content of essential oil components was calculated from the areas of gas chromatography peaks without the use of correction factors. Qualitative analysis was carried out by comparing the linear retention indices. It was found that the composition of the essential oil of Tamarix is very specific. It includes hydrocarbons (9,51%), alcohols (3,46%), aldehydes (2,55%), monoterpene hydrocarbons (5,4%), oxygenated terpenes (23,06%), sesquiterpene hydrocarbons (1,48%), oxygenated diterpenoids (3,37%), and a significant amount of fatty acids and their esters (45,43%). The main components of the essential oil are tetrahydrogeranilacetone (21,35%), nonane (12,63%), decanoic (9,82%) acids and dihydroactin diolide (5,40%).