98 research outputs found
SIMS data for publication "Mechanisms of lipid preservation in archaeological clay ceramics revealed by mass spectrometry imaging" (2020)
No full textThis dataset provides the raw SIMS data for the publication "Mechanisms of lipid preservation in archaeological clay ceramics revealed by mass spectrometry imaging" by Simon Hammann, David J. Scurr, Morgan R. Alexander and Lucy J. E. Cramp. In this paper we used ToF-SIMS and Orbi-SIMS to analyse the lipid distributions in modern and archaeological ceramics to gain better understanding about the mechanisms and modes of lipid preservation in archaeological pottery. Using SIMS we were able for the first direct to map the distributions of lipids in archaeological samples with sub-micrometer spatial resolution and show how they are concentrated in distinct zones. Further data suggested the reaction of calcium carbonate with fatty acids to form the calcium salts as an additional mechanism in lipid preservation
Direct submicron patterning of titanium for bone implants
No full textRecent research evidences the strong modulatory role of controlled submicron and nanoscale topographies on stem cells fate. To harness these physical surface cues for clinical applications, fabrication of nano- and submicron patterns on clinically relevant biomaterials is greatly needed. In this study, an electron beam lithography method for direct patterning (i.e., no use of masters/imprinting steps) of titanium in the submicron range was developed. The process required the use of an etch mask consisting of a double layer of SiO2 and Al, and the positive AR P-6200.04 electron beam resist. An optimum electron beam dose of 288 μC/cm2 was established for writing the desired patterns. The transfer of the patterns into the titanium substrates was achieved by three different steps: inductively coupled plasma etching of the mask in BCl3/Cl2 followed by reactive ion etching of titanium in SF6/CHF3/O2 and a final wet etch of mask residue. Highly ordered arrays of titanium pits with submicron diameters were produced with high reproducibility. This method provides great versatility in pattern design, direct transfer into titanium and increased control of titanium pattern features at submicron to nanoscale enabling clinically relevant and systematic studies on pattern-induced cellular responses.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.ImPhys/Charged Particle OpticsBiomaterials & Tissue Biomechanic
Authentizitätsbewertung einiger unkonventioneller Öle aus der marokkanischen Wüste
No full textInvestigating new sources of vegetable oils is particularly relevant for countries like Morocco, where drought and heat limit the production of traditional oilseed crops, meeting only 20% of national demand. This dissertation characterizes balanites (Balanites aegyptiaca), cactus (Opuntia ficus-indica), and date palm (Phoenix dactylifera) as unconventional sources of vegetable oil in the Moroccan desert focusing on their chemical composition and authenticity assessment.
The first objective was to define the chemical identity of these oils by analysing their main lipid groups: fatty acids (FA), triacylglycerols (TAGs), tocochromanols, and phytosterols. In Balanites kernel oil (BKO) and cactus seed oil (CO), linoleic acid was the dominant fatty acid, followed by oleic, palmitic, and stearic acids. A distinctive feature of CO was its relatively high content (~5%) of vaccenic acid, an isomer of oleic acid. Date seed oil (DSO), by contrast, exhibited a more diverse FA profile, including oleic, lauric, myristic, palmitic, linoleic, and stearic acids which partly explains the high oxidative stability of DSO. TAG analysis supported the FA results, with DSO showing the most diverse profile (34 TAGs). Regarding tocochromanols, BKO was rich in α-tocopherol, CO in γ-tocopherol, while DSO was characterized by high tocotrienol content, especially α-tocotrienol. All three oils shared a similar phytosterol composition, dominated by β sitosterol, campesterol, and Δ5 avenasterol, with CO showing the highest total content.
To explore the effect of geographical origin, it was hypothesized that oil composition varies by collection area and that some variation could be linked to climate conditions such as water deficit and/or temperature. Despite limitations in regional sample size, multivariate statistical analysis was used to identify origin-related trends. The degree and nature of these variations depended on the region and the oil type. For instance, Moroccan BKO samples differed clearly from those collected in Sudan and Mauritania, mainly due to major compounds from all four chemical classes (FA, TAGs, tocochromanol, and phytosterol). In contrast, for DSO at a smaller geographical scale (three Moroccan palm groves), especially minor TAGs were key to distinguishing origin. These findings were discussed in relation to known biosynthetic pathways and stress-related enzymatic responses.
Still within the scope of geographical origin, an untargeted metabolomic approach was applied to DSO as a case study, to determine whether the polar metabolite profile could reflect geographical variation, by revealing clustering trends and potential origin-specific markers not captured by classical lipid analysis. Samples from three Moroccan palm groves were analysed by UHPLC-ESI-QTOF-MS in both positive and negative ionisation modes. PCA results showed a similar clustering trend as observed with lipid composition, with samples from Allougoum forming a distinct group compared to Alnif and Errachidia. Based on these results, an OPLS-DA model was used to identify the discriminative features. Among the top 50 discriminative features, 25 metabolites from various chemical classes were tentatively identified and hydroxy fatty acids were the most represented class. These compounds, reported for the first time in DSO, expand the current understanding of its chemical profile. The data processing workflow used was based entirely on open-source tools and can be readily applied to other oils such as BKO and CO.
For the second aspect of authenticity, adulteration detection, the study aimed to build a machine learning-based model that does not rely on large sets of physical mixtures. Instead, simulation methods were used to generate synthetic data for model training and testing. The hypothesis was that integrating analytical data with simulation and machine learning could enable reliable adulteration detection. CO was used as a test case, with refined sunflower oil (SO) as adulterant. After analysing FA, TAG, and tocochromanol profiles of pure CO and SO, two simulation methods were tested: Monte Carlo (MC) and Conditional Tabular Generative Adversarial Network (CTGAN). MC performed consistently well, even with small datasets, whereas CTGAN was less effective. Using a weighted sum formula, the simulated oils were used to create multiple levels of adulteration. These simulated mixtures were used to train Random Forest (RF) and Neural Network (NN) models. RF outperformed NN, achieving 94% accuracy on simulated data and 90% on real test samples, with better interpretability and lower computational demand. Thus, combining MC simulation with RF is proposed as a robust approach for oil adulteration detection. The methodology, implemented in Python and shared as open-source code, can be easily adapted to other oils with minimal retraining.
Overall, this dissertation presents a multi-approach framework for assessing Moroccan oils authenticity, integrating lipid profiling, untargeted metabolomics, and machine learning. It advances understanding of chemical composition, demonstrates traceability of origin, and offers a robust strategy for detecting adulteration.Die Erschließung neuer Quellen für pflanzliche Öle ist hat besonders relevant für Länder wie Marokko eine große Bedeutung. Hier ist der , wo Dürre und Hitze den Anbau traditioneller Ölpflanzen durch Hitze und Trockenheit stark eingesschränkent und kann derzeit nur etwa 20 % des nationalen Bedarfs gedeckt deckenwerden können. In Ddiese Dissertation werden charakterisiert Balanites (Balanites aegyptiaca), Kaktusfeige (Opuntia ficus-indica) und Dattelpalme (Phoenix dactylifera) als unkonventionelle Ölquellen mit Anbaumöglichkeiten in der marokkanischen Wüste charakterisiert. Der, mit Fokus liegt dabei auf deren Untersuchung der chemischenr Zusammensetzung der Öle und den Möglichkeiten, diese für die Bewertung der Authentizität zu nutzensbewertung.
Das erste Ziel der Arbeit war die chemische Identifizierung Charakterisierung dieser Öle durch die Analysehinsichtlich ihrer wichtigsten LipidbestandteileHauptlipidgruppen: Fettsäuren (FA), Triacylglycerine Triacylglyceride (TAGs), Tocochromanole und Phytosterole. In Balaniteskernöl (BKO) und Kaktussamenöl (CO) dominierte Linolsäure, gefolgt von Ölsäure, Palmitinsäure und Stearinsäure. Charakteristisch für CO war der vergleichsweise hohe Gehalt an Vaccensäure (~5 %), einem seltenen Isomer der Ölsäure. Dattelöl (DSO) zeigte ein deutlich vielfältigeres FA-Profil, einschließlich Ölsäure, Laurinsäure, Myristinsäure, Palmitinsäure, Linolsäure und Stearinsäure. Der hohe Anteil an einfach ungesättigten und gesättigten Fettsäuren kann teilweise , was teilweise die hohe oxidative Stabilität dieses Öls erklärenerklärt. Die Analyse der TAG Zusammensetzung-Analyse bestätigte die FA-Ergebnisse, wobei DSO aufgrund seiner verschiedenen Fettsäuren ein breites Spektrum an TAGdas diverseste Profil (34 TAGs) aufwies. Bezüglich der Tocochromanole war BKO reich an α-Tocopherol, CO an γ-Tocopherol, während DSO durch einen hohen Tocotrienolgehalt, insbesondere an α-Tocotrienol, charakterisiert war. Alle drei Öle wiesen eine ähnliche Phytosterolzusammensetzung auf, dominiert von β-Sitosterol, Campesterol und Δ5-Avenasterol, wobei CO den höchsten Gesamtgehalt zeigte.
In einem zweiten Ansatz wurde die Hypothese aufgestellt, dass die Ölzusammensetzung durch dieHinsichtlich der geographischen Herkunft der Ölsamen beeinflusst wirdwurde die Hypothese aufgestellt, dass sich die Ölzusammensetzung je nach geographischer Herkunft unterscheidet und Unterschiede in der Zusammensetzung auf klimatische Bedingungen wie Wasserdefizit und/oder Temperatur zurückzuführen sein könnten. Trotz der begrenzter begrenzten Probenanzahl pro Region konnten durch multivariate statistische Analysen herkunftsbezogeneein Einfluss der geographischen HerkunftTrends auf die Zusammensetzung der Öle identifiziert werden. Der Grad und die Art der Variation hingen von Region und Öltyp ab. Beispielsweise unterschieden sich marokkanische BKO-Proben deutlich von jenen aus dem Sudan und Mauretanien, hauptsächlich aufgrund der Hauptverbindungen aller vier chemischen Klassen (FA, TAGs, Tocochromanole und Phytosterole). Im Fall von DSO, bBei Betrachtung kleinerer geographischer Maßstäbe Entfernungen (drei marokkanische Palmenhaine), spielten im Fall von DSO, insbesondere minore TAGs eine entscheidende Rolle bei der Unterscheidung der Herkunftsunterscheidung. Diese Ergebnisse wurden im Zusammenhang mit bekannten biosynthetischen Pfaden der Biosynthese dieser Verbindungen und dem Auftreten von stressbedingten Enzymreaktionen diskutiert.
Immer noch im Rahmen der Herkunftsuntersuchung Untersuchungen zum Herkunftsnachweis wurde für DSO ein ungezielter ungerichteter metabolomischer Ansatz angewandt, um zu prüfen, ob das polare Profil der Metabolitenprofil durch die Aufdeckung von Clusterbildungen und die Identifizierung herkunftsspezifischen herkunftsspezifischer Markern geographische Unterschiede widerspiegeln kann, die durch klassische Lipidanalyse nicht erfasst werden. Proben aus drei marokkanischen Palmenhainen wurden mittels UHPLC-ESI-QTOF-MS in positiver positivem und negativem er Ionisationsmodeus analysiert. Eine PCA zeigte eine ähnliche Clusterbildung wie bei der Lipidzusammensetzung, wobei sich der Standort Allougoum deutlich von den Standorten Alnif und Errachidia unterschied. Basierend auf diesen Ergebnissen wurde ein OPLS-DA-Modell verwendet, um diskriminierende Merkmale zu identifizieren. Unter den Top 50 wurden 25 Metaboliten aus verschiedenen chemischen Klassen tentativ identifiziert, wobei Hydroxyfettsäuren am häufigsten vertreten waren. Diese in DSO erstmals beschriebenen Verbindungen erweitern das Verständnis seines chemischen Profils. Der verwendete Workflow für die Datenverarbeitungsworkflow basierte vollständig auf Open-Source-Tools und kann ohne Weiteresauch auf andere Öle wie BKO und CO angewendet werden.
Für den zweiten Aspekt dieser Arbeit, der Authentizität, die Erkennung von Verfälschungen, wurde ein mittels maschinellems Lernen ein Mmodell entwickelt. , Statt der üblichen Verwendung einer großen Zahl von Ölmischungen für die Erstellung des Modellsumfangreicher physikalischer Mischungen wurden Simulationsmethoden eingesetzt, um ausgehend von einer geringen Zahl von Daten zur Zusammensetzung der Öle, synthetisch Daten für das Training und den Test der Modelle zu generieren. Die Hypothese war, dass die Kombination analytischer Daten mit Simulation und maschinellem Lernen eine zuverlässige Erkennung von Verfälschungen ermöglicht. CO wurde als Fallstudie verwendet, wobei raffiniertes Sonnenblumenöl (SO) aufgrund seiner ähnlichen Fettsäurenzusammensetzung als zur Verfälschungsmittel diente. Nach Analyse der FA-, TAG- und Tocochromanol-Profile von reinem CO und SO wurden zwei Simulationsmethoden getestet: Monte Carlo (MC) und Conditional Tabular Generative Adversarial Network (CTGAN). MC lieferte auch bei kleinen Datensätzen konsistent gute Ergebnisse, während CTGAN weniger effektiv war. Auf Basis der MC-Simulation wurden mit einer gewichteten Summenformel unterschiedliche Verfälschungsgrade generiert. Diese simulierten Mischungen dienten zum Training von Random Forest (RF) und Neural Network (NN)-Modellen. RF zeigte die beste Leistung bei der Zuordnung der mit 94 % Genauigkeit bei simulierten und 90 % bei realen Proben. Zudem war RF interpretierbarer und rechenökonomischer als NN. Die Kombination aus MC-Simulation und RF wird daher als robuste Methode zur Ölverfälschungserkennung vorgeschlagen. Die gesamte Methodik wurde in Python implementiert und als Open-Source-Code veröffentlicht, wodurch sie leicht auf andere Öle übertragbar ist.
Insgesamt präsentiert diese Dissertation einen Multi-Ansatz-Rahmen zur Bewertung der Authentizität marokkanischer Öle, der Lipidprofiling, untargeted einen ungerichteten Ansatz des polaren Metabolomics und sowie maschinelles Lernen integriert. Sie erweitert das Verständnis der zur chemischen Zusammensetzung dieser Öle, demonstriert die Möglichkeiten zur Rückverfolgbarkeit des Ursprungs und liefert eine robuste Strategie zur Detektion von Verfälschungen mit preiswerteren Ölen
Method Development for the Determination of Free and Esterified Sterols in Button Mushrooms (<i>Agaricus bisporus</i>)
No full textErgosterol
is the major sterol in button mushrooms (Agaricus
bisporus) and can occur as free alcohol or esterified with
fatty acids (ergosteryl esters). In this study, gas chromatography
with mass spectrometry in the selected ion monitoring mode (GC/MS-SIM)
was used to determine ergosterol and ergosteryl esters as well as
other sterols and steryl esters in button mushrooms. Different quality
control measures were established and sample preparation procedures
were compared to prevent the formation of artifacts and the degradation
of ergosteryl esters. The final method was then used for the determination
of ergosterol (443 ± 44 mg/100 g dry matter (d.m.)) and esterified
ergosterol (12 ± 6 mg/100 g d.m.) in button mushroom samples (n = 4). While the free sterol fraction was vastly dominated by ergosterol
(∼90% of five sterols in total), the steryl ester fraction
was more diversified (nine sterols in total, ergosterol ∼55%)
and consisted primarily of linoleic acid esters
Towards the detection of dietary cereal processing through absorbed lipid biomarkers in archaeological pottery
No full textThe uptake of cereal agriculture in the Neolithic is one of the most important processes in later human prehistory. However, in many parts of Europe, early evidence from pollen or macrofossils is scarce or inconclusive, and there are considerable ambiguities about timing, intensity and the mode of transition to agriculture in these regions. An alternative approach is organic residue analysis, a technique that targets lipids preserved in the walls of unglazed ceramic pots used for storage and processing of foodstuffs. By analysing the molecular and isotopic composition of absorbed lipid residues, many different food items and processing techniques can be detected and distinguished. However, this approach is by-and-large limited to animal-based food sources, and despite their importance, many plant-based food items including cereals are currently not accessible with this approach. For a better understanding of the behaviour of cereal lipids, cooking experiments were conducted and the uptake of cereal-specific compounds such as alkylresorcinols and plant sterols into the ceramic matrix was investigated using a new sensitive method based on GC-Q-ToF-MS. Furthermore, changes in the lipid composition through post-burial degradation was assessed by incubation of potsherds dosed with cereal lipids at 35 °C in compost. The cooking experiments showed that only small quantities of cereal lipids are liberated, but additional lipid sources (meat) can increase the transfer of cereal biomarkers into the ceramic matrix. Anoxic degradation conditions allowed for twentyfold higher levels of alkylresorcinols and twofold higher levels of plant sterols after 20 weeks compared to oxic conditions. Therefore, samples from anoxic burial environments should be targeted and high sensitivity methods are a necessity to detect the trace amounts of cereal-specific biomarkers. To test the applicability of these biomarkers for archaeological pottery, organic residues from ten coarse ware vessels from an anoxic burial context at Vindolanda were analysed. Plant sterols and stanols were detected in three sherds, and two of the sherds also contained traces of alkylresorcinols.</p
Gas chromatographic separation of fatty acid esters of cholesterol and phytosterols on an ionic liquid capillary column
No full textSteryl esters are high molecular weight compounds (600-700. g/mol) regularly present as a minor lipid class in animal and plant lipids. Different sterol backbones (e.g., cholesterol, β-sitosterol and brassicasterol) which can be esterified with various fatty acids can result in highly complex steryl ester patterns in food samples. The gas chromatographic (GC) analysis of intact steryl esters is challenging, since high elution temperatures are required for their elution. On nonpolar GC phases, steryl esters with fatty acids with differing degree of unsaturation (e.g., oleate and linoleate) cannot be separated and there are only few polar columns available with sufficient temperature stability. In this study, we used gas chromatography with mass spectrometry (GC/MS) and analyzed intact steryl esters on a commercial room temperature ionic liquid (RTIL) column which was shortened to a length of 12. m. The column separated the steryl esters both by total carbon number and by degree of unsaturation of the fatty acid. For instance, cholesteryl esters with stearic acid (18:0), oleic acid (18:1. n-9), linoleic acid (18:2. n-6) and α-linolenic acid (18:3. n-3) could be resolved (R≥. 1.3) from each other. By analysis of synthesized standard substances, the elution orders for different steryl backbones and different fatty acids on a given sterol backbone could be determined. Analysis of spreads and plant oils allowed to determine retention times for 37 steryl esters, although a few co-elutions were observed. The ionic liquid column proved to be well-suited for the analysis of intact steryl esters.</p
Déplaire à son public pour un auteur du XVIIIe siècle : le cas de Rousseau
No full textTo displease: this is not a concept, neither a matter of research, but rather a claim--the claim of several writers and artists from the French 18th century, who where reluctant to meet their public’s expectations. The accession of public opinion, whose authority is contested, confirms their desire for autonomy. Among the most eloquent of them is Rousseau. After his Discourse about the origins of inequality among men [1751] inspired his own personal “reformation”, the Genevan citizen unexpectedly proclaims the need to be rid of the long-standing “art to please,” which, up until this point, had ordered social and literary life since the 17th century. However, he is quickly confronted by the dangers of autonomy and a quest for independence that could easily be mistaken as a deceptive form of seduction. In light of this, at the end of the 1750’s, Rousseau decides to renounce his stance as an insolent, forbidding author, and he re-establishes the aim to please, although this time in a different way. The language that is characteristic of the seductive style this author inaugurates is found in his novel La Nouvelle Heloise. But is the novelist able to trump his position, stated in the Lettre à d’Alembert, where he attacks literary pleasure? He would say so; but ironically, it is Rousseau’very own means of seduction that the is attacking when he suggests, indiscreetly, through the lines of his work, that he has been poisoning the public mind.Déplaire : ni une notion constituée, ni un champ de recherche. Mais une revendication : celle de plusieurs écrivains et artistes français au XVIIIe siècle, rechignant à répondre aux attentes du public. L’avènement d’une « opinion publique », dont l’autorité est contestée, renforce leur désir d’autonomie. Parmi les plus éloquents d’entre eux : Rousseau. À partir du Discours sur l’origine de l'inégalité [1751] et à l’occasion d’une éclatante « réforme » personnelle, le Citoyen de Genève établit la nécessité de rompre avec les arts de plaire qui ordonnaient la vie sociale et l’écriture littéraire depuis le XVIIe siècle. Mais il est bientôt confronté aux écueils de la tentation autarcique et d’une revendication d’indépendance immédiatement susceptible de se transformer en stratégie de séduction. Ainsi l’écrivain dénonce, au tournant des années 1760, sa posture d’auteur « rébarbatif ». Ce faisant, il s’essaie à fonder un nouveau plaire, libre et dégagé des obligations courtisanes… La poétique qui accompagne cette réhabilitation d’une forme de séduction se déploie notamment dans La Nouvelle Héloïse. Parvient-elle pour autant à surmonter l’interdit du plaisir littéraire posé par la Lettre à d’Alembert ? Cela n’est pas certain ; car c’est sa propre entreprise de persuasion qu’en dernière instance l’écrivain dénonce, et c’est en empoisonneur public qu’il se présente, secrètement, entre les lignes de son roman
Ancient Foodomics: Analytical Strategies for Reconstruction of Palaeodiets and Implications for Human Health
No full textWhen authors decide to displease their audience : Rousseau in his century
No full textDéplaire : ni une notion constituée, ni un champ de recherche. Mais une revendication : celle de plusieurs écrivains et artistes français au XVIIIe siècle, rechignant à répondre aux attentes du public. L’avènement d’une « opinion publique », dont l’autorité est contestée, renforce leur désir d’autonomie. Parmi les plus éloquents d’entre eux : Rousseau. À partir du Discours sur l’origine de l'inégalité [1751] et à l’occasion d’une éclatante « réforme » personnelle, le Citoyen de Genève établit la nécessité de rompre avec les arts de plaire qui ordonnaient la vie sociale et l’écriture littéraire depuis le XVIIe siècle. Mais il est bientôt confronté aux écueils de la tentation autarcique et d’une revendication d’indépendance immédiatement susceptible de se transformer en stratégie de séduction. Ainsi l’écrivain dénonce, au tournant des années 1760, sa posture d’auteur « rébarbatif ». Ce faisant, il s’essaie à fonder un nouveau plaire, libre et dégagé des obligations courtisanes… La poétique qui accompagne cette réhabilitation d’une forme de séduction se déploie notamment dans La Nouvelle Héloïse. Parvient-elle pour autant à surmonter l’interdit du plaisir littéraire posé par la Lettre à d’Alembert ? Cela n’est pas certain ; car c’est sa propre entreprise de persuasion qu’en dernière instance l’écrivain dénonce, et c’est en empoisonneur public qu’il se présente, secrètement, entre les lignes de son roman.To displease: this is not a concept, neither a matter of research, but rather a claim--the claim of several writers and artists from the French 18th century, who where reluctant to meet their public’s expectations. The accession of public opinion, whose authority is contested, confirms their desire for autonomy. Among the most eloquent of them is Rousseau. After his Discourse about the origins of inequality among men [1751] inspired his own personal “reformation”, the Genevan citizen unexpectedly proclaims the need to be rid of the long-standing “art to please,” which, up until this point, had ordered social and literary life since the 17th century. However, he is quickly confronted by the dangers of autonomy and a quest for independence that could easily be mistaken as a deceptive form of seduction. In light of this, at the end of the 1750’s, Rousseau decides to renounce his stance as an insolent, forbidding author, and he re-establishes the aim to please, although this time in a different way. The language that is characteristic of the seductive style this author inaugurates is found in his novel La Nouvelle Heloise. But is the novelist able to trump his position, stated in the Lettre à d’Alembert, where he attacks literary pleasure? He would say so; but ironically, it is Rousseau’very own means of seduction that the is attacking when he suggests, indiscreetly, through the lines of his work, that he has been poisoning the public mind
Analysis of Intact Cholesteryl Esters of Furan Fatty Acids in Cod Liver
No full textFuran fatty acids (F-acids) are a class of natural antioxidants with a furan moiety in the acyl chain. These minor fatty acids have been reported to occur with high proportions in the cholesteryl ester fraction of fish livers. Here we present a method for the direct analysis of intact cholesteryl esters with F-acids and other fatty acids in cod liver lipids. For this purpose, the cholesteryl ester fraction was isolated by solid phase extraction (SPE) and subsequently analyzed by gas chromatography with mass spectrometry (GC/MS) using a cool-on-column inlet. Pentadecanoic acid esterified with cholesterol was used as an internal standard. GC/MS spectra of F-acid cholesteryl esters featured the molecular ion along with characteristic fragment ions for both the cholesterol and the F-acid moiety. All investigated cod liver samples (n = 8) showed cholesteryl esters of F-acids and, to a lower degree, of conventional fatty acids. By means of GC/MS-SIM up to ten F-acid cholesteryl esters could be determined in the samples. The concentrations of cholesteryl esters with conventional fatty acids amounted to 78-140 mg/100 g lipids (mean 97 mg/100 g lipids), while F-acid cholesteryl esters were present at 47-270 mg/100 g lipids (mean 130 mg/100 g lipids).</p
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