Linear Retention Indices Research Articles

Non-psychoactive cannabinoids identification by linear retention index approach applied to a hand-portable capillary liquid chromatography platform.

The aim of the present research was the application of the linear retention index (LRI) system for the identification of non-psychoactive cannabinoids using a portable LC instrument. The miniaturization, viz. the use of very low quantities of mobile phase, enabled the development of a compact mobile system to be used for in situ analysis, also according to a green and cost-saving approach. In particular, new capillary LC (cap-LC) methods coupled with UV detection were developed for the analysis of extracts of Cannabis sativa L. Two setups were explored to achieve the efficient separation of twenty-four cannabinoids: a single column setup which exploited a sub-2µm packing to increase the chromatographic resolution, and a dual-column setup based on the serial connection of two different stationary phases, each coupled to an UV detector. The latter allowed the determination of two LRI values for each analyte, thus increasing the identification power. Moreover, since two different wavelengths were used on the LED-based UV detectors, the ratio of the absorbances measured on each chromatographic trace represented a third identification criterion, thus fulfilling the recommendations of the Scientific Working Group for The Analysis of Seized Drugs (SWDRUG) about the categories of analytical techniques to be used and the minimum number of parameters required for the unambiguous identification of drugs. The obtained results could be used for the development of a novel analytical method for fast and automatic in situ forensic investigations and hemp breeding programs, also minimizing the consumption of both sample and solvent.

COMPONENT COMPOSITION OF PHENOLIC COMPOUNDS AND TERPENOIDS OF THE ANGIOPROTECTIVE HERBAL COMPOSITION

The study of the component composition of phenolic and terpenoid compounds of the angioprotective herbal composition was carried out. Alcohol extraction of the angioprotective herbal composition was studied by MC-HPLC-UV method. The analysis used solutions of commercial samples of reference substances manufactured by Sigma-Aldrich (USA), Chem-Fages, Extrasynthese, Lione (France), Beijing (China). Seven phenolic compounds have been identified: quercetin, isoramnetin, rutin, isoquercitrin, narcissin, isoramnetin-3-O-glucoside, phenolcarboxylic acid 5-O-caffeylquinic. The total content of flavonoids is 11.64 mg/g, phenolcarboxylic acid – 2.30 mg/g. Among the isolated flavonoids rutin (3.35±0.06 mg/g), isoquercitrin (3.14±0.06 mg/g), narcissin (4.15±0.09 mg/g), phenolcarboxylic acid – 5-O-caffeylquinic (2.30±0.05 mg/g) prevail. The essential oil was obtained by hydrodistillation; analysis was performed by gas chromatography-mass spectrometry on an Agilent Technologies (6890N) instrument with a quadrupole mass spectrometer. The identified components were performed by comparing the linear retention indices and total mass spectra of the compounds with the data from the Nist 11 library and commercial samples. In the herbal composition of the essential oil, 21 components have been identified, the main of which are salicylic aldehyde (in the total amount is 58.30%), methyl salicylate (16.17%). The triterpene saponins of the angioprotective herbal composition are represented by calendulosides A and B, escin. The amount of triterpene saponins is 1.08±0.05%. The results of the quantitative analysis were processed statistically, the data are presented as the mean and ± standard deviation, SD.

Gas chromatography-mass spectrometry of eight aminoindanes: 2-Aminoindane, N-methyl-2-, 5-methoxy-, 5-methoxy-6-methyl-, 4,5-methylenedioxy-, 5,6-methylenedioxy- and 5-iodo-2-aminoindane, and rasagiline.

Aminoindanes are one class of many new psychoactive substances that have emerged over the last decade. Analogues of 2-aminoindane (2-AI) are being encountered in crime laboratories and analytical data for most aminoindanes are limited. Interpretation and optimization of gas chromatography-mass spectrometry data will enhance reliability in characterizing aminoindanes. This study focuses on the electron ionization mass spectrometric fragmentation of eight aminoindane analogues and the gas chromatographic separation of these eight aminoindane analogues using four different column stationary phases, Rxi®-1Sil MS, Rxi®-5Sil MS, Rxi®-35Sil MS, and Rxi®-624Sil MS. Split injection (25:1) was utilized and each column had the same configuration (30 m × 25 mm × 0.25 μm), with the exception of the Rxi®-624Sil MS column (30 m × 25 mm ×1.4 μm). Mass spectra showed strong molecular ions for all aminoindanes, except for rasagiline that produced a uniquely abundant [M - 1] ion. Other characteristic fragmentation that was present for all the aminoindanes included indane and indene ions (m/z 115-117), the tropylium ion (m/z 91), and subsequent loss of diene to produce smaller ions that followed: phenyl (m/z 77), cyclopentadienyl (m/z 65), cyclobutadienyl (m/z 51), and cyclopropenyl (m/z 39). Separation of eight aminoindanes was optimized, and linear retention indices were determined for the compounds on four capillary columns. Based on the retention data, all eight aminoindanes were resolved on an Rxi®-624Sil MS column. Each aminoindane exhibited unique fragmentation ions in the mass spectra to distinguish between similar analogues. The results of this study will strengthen the analytical profiles of 2-AI and seven analogues, assisting forensic scientists in their analysis and identification of these substances.

Dietary Intake of Coumarins and Furocoumarins through Citrus Beverages: A Detailed Estimation by a HPLC-MS/MS Method Combined with the Linear Retention Index System.

Official regulations concerning the maximum number of substances in food are introduced as a consequence of possible adverse effects, after oral administration. In this regard, analytical methods are necessary in order to determine specific targets. Among oxygen heterocyclic compounds (OHCs, that are furocoumarins, coumarins and polymethoxyflavones), only coumarin is subject to restriction by the Regulation (EC) No 1334/2008 of the European Parliament. Furocoumarins are known for their phototoxicity and other side effects due to their dietary intake; however, an official limit about the maximum content of these compounds in food is still missing. The lack of information about the real amount of these compounds in food is responsible for the conflicting opinions about the introduction of an official limit. The HPLC-MS/MS method here proposed, in combination with the linear retention index system, represents an innovative analytical strategy for the characterization of OHCs in citrus beverages. Several types of drinks were analysed in order to quantify 35 OHCs in total. This method is suitable for the quality control of OHCs in food and the obtained results may be considered as informative data useful for the regulatory authorities in the emission of new opinions and for a potential new regulation in this field.

Linear retention index approach applied to liquid chromatography coupled to triple quadrupole mass spectrometry to determine oxygen heterocyclic compounds at trace level in finished cosmetics

In the European Union, cosmetic products are regulated by the Cosmetics Regulation (EC) No. 1223/2009. The Analytical Working Group of the International Fragrance Association (IFRA) suggested that a new sensitive analytical method is needed to determine psoralens in finished cosmetic products. This research provides an HPLC-MS/MS method for the quality control of 20 furocoumarins, 8 coumarins and 7 polymethoxyflavones in cosmetics. Thanks to the high sensitivity of the tandem mass spectrometry detection in Multiple Reaction Monitoring mode, psoralens contained in trace have been quantified in different products. The Limits of Quantifications were in the range 0.3-74 μg L−1. A reliable identification was achieved combining the Linear Retention Index (LRI) system with the MS and MS/MS libraries. In particular, the attribution was based on the spectra similarity filtered by the LRI parameter. The robustness and reproducibility of the LRI approach was demonstrated by the comparison of the HPLC-MS/MS results here reported with those obtained in our previous study, by using an HPLC-PDA system.This method could be taken into account for quality control of furocoumarins in cosmetics, and by the main associations, such as IFRA, for the purpose of issuing new opinions.

Development of a Novel Microwave Distillation Technique for the Isolation of Cannabis sativa L. Essential Oil and Gas Chromatography Analyses for the Comprehensive Characterization of Terpenes and Terpenoids, Including Their Enantio-Distribution.

A microwave distillation method was optimized for the extraction and isolation of cannabis essential oil from fresh and dried hemp inflorescences. The developed method enabled us to obtain a distilled product rich in terpenes and terpenoid compounds, responsible of the typical and unique smell of the cannabis plant. The distillate from different hemp cultivars, including Kompolti, Futura 75, Carmagnola, Felina 32 and Finola were characterized by using a gas chromatograph equipped with both mass spectrometer and flame ionization detectors. In a single chromatographic run, the identity and absolute amounts of distilled compounds were determined. Peak assignment was established using a reliable approach based on the usage of two identification parameters, named reverse match, and linear retention index filter. Absolute quantification (mg g−1) of the analytes was performed using an internal standard method applying the flame ionization detector (FID) response factors according to each chemical family. An enantio-GC-MS method was also developed in order to evaluate the enantiomeric distribution of chiral compounds, an analytical approach commonly utilized for establishing the authenticity of suspicious samples.

Influence of Citrus Flavor Addition in Brewing Process: Characterization of the Volatile and Non-Volatile Profile to Prevent Frauds and Adulterations

In the last few years, the flavored beer market has increased significantly. In particular, consumers showed a growing interest in citrus-flavored beers. Citrus fruits contain, among other class of compounds, terpenes and terpenoids and oxygenated heterocyclic compounds. The absence of a specific legislation concerning beer flavored production and ingredients reported on the labels makes these beers subject to possible adulterations. Solid phase micro extraction (SPME) followed by gas chromatographic–mass spectrometry (GC-MS) and gas chromatographic-flame ionization detector (GC-FID) analysis of the volatile profile together with the characterization of the oxygen heterocyclic compounds through high performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS) demonstrated to be a powerful analytical strategy for quality control. In this study, we combined the volatile and non-volatile profiles of “citrus flavored mainstream beers”, in order to evaluate the authenticity and determine markers to prevent food frauds. The changes in the aroma composition of the unflavored types after the addition of peel, or citrus essential oil were also evaluated. The linear retention index (LRI) system was used for both techniques; in particular, its application in liquid chromatography is still limited and represents a novelty. The coupling of the high sensitivity of the HPLC MS/MS method with the LRI system, it has made possible for the first time a reliable identification and an accurate quantification of furocoumarins in citrus-flavored beers.

The retention index approach in liquid chromatography: An historical review and recent advances

Historically, retention parameters were reliably used as identification criterion in chromatographic analytical systems. However, pure analytical standards are necessary to determine the retention behaviour of a given compound. In recent decades, mass spectrometer (MS) became the detector of choice to obtain structural information on unknown peaks, thanks to the elucidation of fragments, often arisen from the loss of specific functional groups. The cost and the level of experience of the operators is surely higher compared to the use of retention data. Therefore, the aim of the present review is to describe the efforts in the introduction of the Linear Retention Index (LRI) in routine, interlaboratory applicable identification procedures. The requirements and the main challenges will be discussed, even compared to gas chromatography methods, in which LRI is stably used for identification purposes, usually in combination with MS spectral libraries. The higher number of LC-amenable molecules and the wide range of LC mobile phase compositions make the building of universal LRI database a very challenging task. The limitations encountered in the past decades are reported, together with new proposals in order to overcome such issues.

A comparative study of volatile flavor components in four types of zaoyu using comprehensive two‐dimensional gas chromatography in combination with time‐of‐flight mass spectrometry

Volatiles of four zaoyu (Chinese traditional fermented fish) products prepared from different species of marine fish were analyzed by headspace solid-phase micro-extraction (HS-SPME) and comprehensive two-dimensional gas chromatography in combination with time-of-flight mass spectrometry (GC × GC/TOFMS). First, a 50/30 µm DVB/CAR/PDMS was used and the influence of several parameters on the efficiency of HS-SPME such as extraction temperature, time, salting-out effect, and stirring were optimized, odor activity values (OAVs) of volatile compounds were computed based on the threshold values of aroma constituents; the characteristic volatiles and their odor characteristics of the four zaoyu were investigated. The results demonstrated that the most effective extraction of the analytes was obtained with a 40 min extraction at 50°C with the addition of 20% NaCl and stirring at 300 r/min. Under these conditions, a total of 288 volatile components were tentatively identified based on mass spectra and comparison of linear retention indices in the four zaoyu products. Authenticated compounds included aldehydes, esters, alcohols, ketones, furans, lactones, nitrogen compounds, sulfur compounds, terpenes, phenols, etc. Among the identified types of volatile compounds, the number of esters is the largest, whereas the content of aldehydes is the highest. The results of OAVs comparisons proved that both aldehydes and esters provided the most significant contribution to the aromas of zaoyu, and each zaoyu product had its own unique active flavor components. Moreover, the OAVs of active flavor compounds common to the four examined zaoyu varied significantly. Our results substantiated that GC × GC/TOFMS could provide a robust technical means to understand the flavor characteristics of zaoyu and allow us to better evaluate and improve the flavor quality of the products with complex food matrix like zaoyu. Practical applications The method present in this research is suitable to characterize the volatile constituents of aquatic products, and could also be used for component characterization of similar complex samples such as fermented fish and foods. Understanding the key aroma compounds of fermented fish and its formation mechanism could provide a guide of process optimization and flavor regulation, contributing to further studies related to volatile compounds in the field of food flavor analysis.

Development and validation of analytical method for identification of new psychoactive substances using linear retention indexes and gas chromatography-mass spectrometry

New Psychoactive Substances (NPS) are quickly developing to evade legislation, posing unprecedented challenges to public health and law enforcement authorities around the world. The aim of this work was to develop and validate a simple and reliable non-target gas chromatography/mass spectrometry (GC/MS) analytical method based on linear retention indexes for the expeditious identification of NPS without the need of analytical standards. The method was optimized and validated for 22 different drugs covering ten categories: phenethylamines (amphetamine, MDMA, methamphetamine, 25CNBOMe, 2-FA, 5-MAPB), “classic” drugs (cocaine, ephedrine, THC, heroine), synthetic cannabinoids (JWH-081, AM-2201, JWH-210, MAM-2201), piperazines (o-CPP, p-CPP), tryptamines (5-MeO-MiPT), synthetic cathinones (N-ethylpentylone), synthetic opioids (U-47700), aminoindanes (5-IAI), plant-based substances (Salvinorin-A) and “other” (methiopropamine). Three figures of merit (Selectivity, Precision and Robustness) were evaluated with retention index confidence intervals ranging from 0.5 to 20.6 i.u. and relative standard deviations in the range of 0.003% to 0.027% (repeatability) and 0.02% to 0.29% (intermediate precision). A general equation for estimating linear retention index variation as a function of retention time tolerance has been derived. This result in combination with a 2III6−3 fractional factorial design allowed to conclude column polarity to be only statistically relevant factor as compared to gas flow, split ratio, injection temperature, temperature program offset and column brand.

Characterization of 9 Gas Chromatography Columns by Linear and Lee Retention Indices for Polychlorinated Biphenyls and Polychlorinated Naphthalenes

Polychlorinated biphenyls (PCBs) and naphthalenes (PCNs) are ubiquitous environmental contaminants with varying degrees of toxicity. There are hundreds of possible congeners with similar chemical characteristics, which make these compounds difficult to isolate in environmental samples. Historically, PCBs and PCNs were identified by using an Aroclor or Halowax mixture instead of the individual compounds, which was impractical because of limited numbers of individual standards. A retention index database was developed with all 209 PCBs and 36 PCNs to help identify these chemicals in environmental and biological matrixes. This study uses linear and Lee retention indices to identify all 209 PCBs and 36 PCNs on nine gas chromatography columns. The most toxic congeners, the 12 dioxin-like PCBs, were compared across all columns to determine which stationary phases gave the best selectivity for those compounds. Column selectivity was also examined to determine columns for confirmatory analyses and GC×GC separations. The Rxi-17SilMS demonstrated the most drastic difference in PCB selectivity and, to a lesser extent, PCNs when compared with the other eight columns and could work as a confirmatory column or as a 2nd dimension column for GC×GC separations.

Traceability of Volatile Organic Compounds from Hypericum perforatum in Fresh and Dried Form and in Essential Oil

Microextraction in solid phase from headspace and GC-MS analysis was the method of studying the flowers of Hypericum perforatum in fresh and dry form.The essential oil obtained by hydrodistillation was also analyzed by GC-MS. Identification of the substances was made by comparison of mass spectra with NIST library and standard alkanes were used for the calculation of the linear retention index. The identified compounds were grouped into classes of substances: monoterpene hydrocarbons, sesquiterpene hydrocarbons, oxygenated monoterpenes, oxygenated sesquiterpenes, non-terpene hydrocarbons. The main common constituents were as follows: caryophyllene, β-ocimene, α-pinene, β-pinene, octane-2-methyl. The abundance of the majority compounds, common to the three forms of the plant: essential oil,fresh, and dried plants, was compared.

Lipid profile of fish species by liquid chromatography coupled to mass spectrometry and a novel linear retention index database.

In a previous article, Rigano etal. established a new linear retention index system for the identification of triacylglycerols by liquid chromatography methods only on the basis of the retention behavior and independently from many experimental parameters. In that work, a database of 209 compounds was built, but only 54 of them, typical of vegetable oils, were confirmed by mass spectrometry. The aim of the present research is to extend the applicability of the novel approach to more complex samples, such as fish lipid extracts, and assess the complementarity between mass spectromtery and retention information to achieve univocal identification. With this purpose, a new software was implemented to make the identification process easy and automatic as in gas chromatography-mass spectrometry where the retention index filter is added in the spectral search to discriminate between compounds with similar mass spectrometry spectra. A total of 69 species were identified and, thanks to their baseline separation obtained by an ultra high performance liquid chromatography method, a semiquantification was also performed. The species under investigation were Dicentrarchus labrax, coming from aquaculture and the wild. Some differences in their native lipid composition were observed, probably related to a different diet. A major number of samples would be necessary to confirm such a preliminary finding.

Conversion method for linear retention indices in gas chromatography acquired using n-alkanes and n-fatty acid methyl esters

Retention index (RI) is a powerful tool for gas chromatography-based structure elucidation of various compounds. In this study, linear RIs based on n-alkanes and n-fatty acid methyl esters in different temperature programs were fitted. Nearly identical first-order linearities were acquired with different temperature programs. The linear equations were y=1.0051x+318.51 (r2=1) and y=1.0362x+562.519 (r2=1) for polar (packed with polyethylene glycol) and semi-standard non-polar (packed with 5% diphenyl/95% dimethylpolysiloxane) columns, respectively. The variables x and y in the equations stand for RIs based on n-fatty acid methyl esters and n-alkanes, respectively. The established linearity was then verified using the reference RIs collected in the NIST mass spectral library, Golm metabolite library, and Fiehnmetabolite library. The RI values converted using both the acquired equations finely matched those in the references. The established relationship between the two kinds of RIs can be used to expand the RI references and decrease the number of RI acquisition experiments.

Quality assessment and differentiation of Aucklandiae Radix and Vladimiriae Radix based on GC-MS fingerprint and chemometrics analysis: basis for clinical application.

Vladimiriae Radix, a geo-authentic medicinal herb found in Sichuan Province in China, is highly similar in chemical composition and pharmacological activity to Aucklandiae Radix. It is often used in local practice and as a substitute for Aucklandiae Radix in the treatment of gastrointestinal tract diseases. However, Vladimiriae Radix is preferred to Aucklandiae Radix in traditional Chinese medicine in Sichuan. In order to compare the difference in quality between the two species and differentiate them according to their chemical profiles, and further to explain the rationality of using Vladimiriae Radix as a substitute and explore the reason for the medication preference in Sichuan, similarity was evaluated using gas chromatography-mass spectrometry (GC-MS) fingerprinting and chemometric analysis. Volatile compounds were identified by comparing mass spectra with spectral data from the National Institute of Standards and Technology library 14.L (NIST 14.L) and the linear retention indices (RI) with those previously reported. The results showed that the similarity between the samples from Aucklandiae Radix (>96%) was greater than that of Vladimiriae Radix (>80%). In addition, 41 and 38 compounds were identified in 10 batches of Vladimiriae Radix and Aucklandiae Radix, respectively, and 21 compounds were common to both species, of which dehydrocostus lactone and aplotaxene were abundant in both. However, γ-patchoulene, longicyclene, β-gurjunene, humulene1,2-epoxide, and β-patchoulene were unique to Vladimiriae Radix, while 4-terpineol, α-ionone, trans-α-bergamotene, γ-selinene, and camphene were characteristic compounds of Aucklandiae Radix. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) suggested that the two species were well differentiated with regard to the level of essential oils. Orthogonal partial least squares discriminant analysis (OPLS-DA) further showed that compounds including costol, aplotaxene, caryophyllene, humulene, and β-eudesmol, together with the characteristic compounds of the two species, could be regarded as potential markers for differentiation, among which β-eudesmol, which is richer in Vladimiriae Radix, and β-patchoulene, which is unique to Vladimiriae Radix, have potential therapeutic effects on gastrointestinal diseases. The results obtained in this study distinguished Vladimiriae Radix and Aucklandiae Radix on a chemical level, and the similarity in chemical constituents may provide a basis for the rationality of Vladimiriae Radix as a substitute, while β-patchoulene and β-eudesmol existing in Vladimiriae Radix provide a theoretical basis for its preferential use in Sichuan. The analysis method established here has important implications for the quality control and differentiation of Vladimiriae Radix and Aucklandiae Radix, which can also serve as a reference for the identification of similar species. Graphical abstract.

Experience with the application of gas chromatography-mass spectrometry in combination with solid-phase microextraction for the study of the composition of volatile organic compounds in matrices with the high fat content

Current article presents a methodological approach for a comparative study of the composition of volatile organic compounds ( VOCs ) in a natural product and a nature-identical flavoring substance. The identification of VOCs was performed by gas chromatography-mass spectrometry without reference compounds. The identification was made based on coincidence of the experimental and reference mass spectra and linear retention indices. During the first step, the closest match factor substance was selected based on the library search. During the second step, the result was verified by the means of experimental and reference retention indices data proximity. The reference retention indices were selected considering the identity of the experimental conditions (chromatographic stationary phase, temperature programming mode). The impossibility of identification of aroma components in acetonitrile extract of fragrance was shown due to the overlapping of their peaks with peaks of di- and tri- glycerides of fatty acids. The extraction and concentration of VOCs from vapor were carried out using the head space solid-phase microextraction. The fragrance content investigation revealed 39 volatile organic compounds including propylene glycol and triacetin as the markers of synthetic fragrances. In natural cocoa butter, also 39 volatile organic compounds were identified. All of them were common for the fermented cocoa beans. Pyrazines derivatives, characteristic of cocoa aroma, were presented with the following 7 components: 2,3-dimethylpyrazine; 2,5-dimethylpyrazine; ethylpyrazine; 2-methyl-6-ethylpyrazine; 2,3,5-trimethylpyrazine, 2,5-dimethyl-3-ethylpyrazine; tetramethylpyrazine. In quantitative terms, the isomeric 2,3-butandiols predominate in the head space of natural cocoa butter accounting for 37 percent of total VOC content. The analytical technique used allows investigation of multicomponent objects including the heterogeneous ones. Key words: gas chromatography-mass spectrometry, head space solid-phase microextraction, mass spectra, retention indices, fragrance DOI: http://dx.doi.org/10.15826/analitika.2020.24.1.003 E. Savelieva E. Kessenikh and L. Gustyleva Research Institute of Hygiene, Occupational Pathology and Human Ecology, g/p Kiz’molovskii, Vsevolozhskii raion, Leningradskaia oblast’, 188663, Russian Federation

In-Depth Qualitative Analysis of Lime Essential Oils Using the Off-Line Combination of Normal Phase High Performance Liquid Chromatography and Comprehensive Two-Dimensional Gas Chromatography-Quadrupole Mass Spectrometry.

The present research is focused on the in-depth qualitative analysis of three types of lime essential oil (EO), viz., Key (A and B) and Persian, using the off-line combination of normal phase high performance liquid chromatography (NP-HPLC) and comprehensive two-dimensional gas chromatography–quadrupole mass spectrometry (GC × GC-QMS). The first analytical dimension (NP-HPLC) was exploited for the isolation of the hydrocarbon constituents from the oxygenated ones. Each fraction was then reduced in volume and analyzed using (cryogenic modulation) GC × GC-QMS. Peak assignment was carried out through the combined use of mass spectral database and linear retention index matching processes. The powerful four-dimensional technology enabled the separation and identification of a very high number (153) of lime essential oil volatile compounds.

Characterization of monoacylglycerols and diacylglycerols rich in polyunsaturated fatty acids produced by hydrolysis of Musteleus mustelus liver oil catalyzed by an immobilized bacterial lipase

The use of an immobilized Serratia. sp W3 lipase as a replacement for the standard pancreatic lipases in the hydrolysis of liver oil from the Musteleus mustelus was studied. Monoacylglycerols (MAGs) and diacylglycerols (DAGs) containing ω-3 polyunsaturated fatty acids, namely eicosapentaenoic and docosahexaenoic acids were produced in hexane solvent at reaction temperatures reaching 55 °C with a molar triacylglycerol conversion over than 75 ± 5% in 24 h showing excellent hydrolysis characteristics. The favorable conditions for the hydrolysis reaction allowed fats with higher melting points to be analyzed facilitating the coupling of the hydrolysis reaction to the later steps in the analytical protocol.The lipid composition was elucidated for the first time by employing a highly efficient UHPLC-MS method with a novel embedded linear retention index approach. MAGs and DAGs obtained during the enzymatic hydrolysis could be used for the production of glycerol based emulsifiers of nutritional interest.

Combining linear retention index and electron ionization mass spectrometry for a reliable identification in nano liquid chromatography

The present research is focused on the object to improve identification capability in liquid chromatography (LC), by creating a system as similar as possible to gas chromatography (GC), where the combination/complementarity of Linear Retention Index (LRI) and Electron Ionization Mass Spectrometry (EI-MS) data makes the identification process easy, automatic and reliable. Conversely, in LC the untargeted characterization of real-world samples is still a challenge, due to the not repeatable and poorly informative nature of typical atmospheric pressure ionization mass spectrometry, normally hyphenated to LC. In the last decades the miniaturization of LC instrumentation together with the considerable progresses in MS vacuum pump capability has made the LC-EI-MS hyphenation more feasible. In the present work, a prototypal nanoLC-EI-MS system was used for the determination of typically LC-amenable compunds, such as coumarins, furocoumarins and polymethoxyflavones in citrus essential oils. All the compounds provided high quality EI-MS spectra, evaluated by the comparison with thousands of spectra present in commercial EI-MS libraries. Spectral similarities major than 80% were achieved.Furthermore, an LRI system, based on the use of an alkyl aryl ketone homologue reference series, was proposed as additional filter to achieve a univocal identification. Then, a novel dual-filter LRI/EI-MS library was built and resulted very helpful in the case of isomeric compounds characterized by identical EI-MS spectrum, but different retention behaviour. The very low inter-day variability attained for each LRI value, together with the satisfactory chromatographic resolution of the developed method, led to a 100% reliability of the identification process based on LRI.

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.