Search results for "Saponification"
showing 10 items of 29 documents
Flow injection determination of free and total cholesterol in animal greases using enzymes in non-aqueous media
1998
A non-covalently coimmobilized bienzymic reactor of horseradish peroxidase (HRP) and cholesterol oxidase (COD), operating in a continuous organic flowing stream of 1 × 10–3 M p-anisidine in buffer-saturated (pH 7.0) toluene, has been employed for cholesterol determination in animal greases, such as pig, beef, and chicken fat, and codfish liver oil. The method provides a good linear relationship up to 1.8 × 10–3 M cholesterol and average recoveries of 99.5%, a high sensitivity, with a detection limit of 1 × 10–6 M of cholesterol and a good precision (an interday RSD of 1.8% for the determination of total cholesterol in a codfish oil sample). The method permits the direct spectrophotometric d…
Levels, fingerprint and daily intake of polycyclic aromatic hydrocarbons (PAHs) in bread baked using wood as fuel
2009
Concentrations, fingerprint and daily intake of 16 PAHs in 15 bread samples baked using wood as fuel are examined in this work. Analysis was performed by GC/MS after saponification of the samples and clean up of the extract. The total concentration of the 16 analytes varies from 6 to 230 microg/kg on dry weight (d.w.). The better extraction procedure was estimated by analyzing test-samples and using different extraction methods. Additionally, for every analyzed sample, the extraction yield has been determined by the use of surrogate standards. Extraction yields were never less than 77% and in most cases almost 100%. The profiles of PAHs (percentage) are similar for all the analyzed samples …
Untersuchungen zur friesschen verschiebung an hydroxybenzylphenol-derivaten
1974
An den Acetaten 2a–c, 3b, 4b und 4d von sechs Hydroxybenzylphenol-Derivaten wurde die Friessche Verschiebung mit AlCl3 als Katalysator in Nitrobenzol bei Temperaturen zwischen 40 und 70°C durchgefuhrt. Neben den zu erwartenden Hauptprodukten der Friesschen Verschiebung konnte durch Saulenchromatographie eine Reihe von Zwischen- und Nebenprodukten isoliert werden. Daraus ging hervor, das wahrscheinlich eine teilweise Verseifung der Acetate als Nebenreaktion stattfindet. Eine Wanderung der Acetylgruppe an den benachbarten Phenolbaustein des gleichen Molekuls konnte nicht beobachtet werden. Samtliche Verbindungen, einschlieslich der Ausgangsprodukte, wurden durch ihre IR- und 1H-NMR-Spektren c…
Application of accelerated solvent extraction followed by gel performance chromatography and high-performance liquid chromatography for the determina…
2005
Accelerated solvent extraction (ASE) has been evaluated as a fast alternative to methanolic saponification for the extraction of 12 polycyclic aromatic hydrocarbons (PAHs) from mussel tissue. Several solvent systems and different operating conditions were investigated. The mixture dichloromethane-acetone (1:1, v/v) gave the best recoveries at 125 degrees C and 1500 psi, in a total time of 10 min. No yield difference was found between freeze-drying (Fd) or drying the wet mussel with diatomaceous earth (Ded) prior to extraction. The ASE method was validated using the standard reference material SRM 2977, a freeze-dried mussel tissue with naturally present organic contaminants. The performance…
Isomerisierung von 2‐Alkoxycyclopropancarbonsäuren – Eine effektive Synthese von 4‐Oxocarbonsäuren
1983
(Z/E)-2-Alkoxycyclopropansaureester 2/3 werden aus Enolethern 1 und Diazoessigester hergestellt. Durch Verseifen entstehen die (Z/E)-2-Alkoxycyclopropancarbonsauren 4/5, welche in Wasser/Methanol Stereomutation zeigen. Diese Isomerisierung wird an (E)-2-Methoxy-2-phenyl-cyclopropancarbonsaure (5a) in deuterierten Losungsmitteln untersucht und mechanistisch interpretiert. Beim Erwarmen in Wasser/Methanol offnen sich die Verbindungen 4/5 quantitativ zu den entsprechenden 4-Oxocarbonsauren 6. Isomerisation of 2-Alkoxycyclopropanecarboxylic Acids – An Effective Synthesis of 4-Oxo Carboxylic Acids (Z/E)-2-2-Alkoxycyclopropanecarboxylic esters 2/3 were prepared from enol ethers 1 and ethyl diazoa…
Analyse von Copolymeren aus Vinylestern und Acrylestern
1978
Die Copolymeren aus Vinyl- und Acrylestern werden in abgeschmolzenen Ampullen durch 2 M NaOH verseift. Die aus den Vinylester-Grundbausteinen gebildeten Sauren werden durch potentiometrische Titration bestimmt; liegen verschiedene Vinylester nebeneinander vor, so wird das Mengenverhaltnis der Sauren gaschromatographisch ermittelt. Die bei der Verseifung aus den Acrylester-Grundbausteinen entstehenden Alkohole werden gaschromatographisch identifiziert und gegen tert-Butanol als internen Standard quantitativ bestimmt. Ein besonderer Vorteil der Methode besteht darin, das auch wasrige Dispersionen ohne vorherige Abtrennung des Copolymeren eingesetzt werden konnen. The copolymers from vinyl est…
Synthesis of optically pure alkynols
1993
Abstract (R,S)-1-alkylprop-2-yn-1-ols have been separated by a 2-step procedure, esterification with N-p-tosyl-(L)-phenylalanine (or valine), recrystallisation of the diastereomeric esters from ethanol/hexane and saponification of the optically pure esters.
Characterization of the alcoholic fraction of vegetable oils by derivatization with diphenic anhydride followed by high-performance liquid chromatogr…
2008
Abstract Aliphatic and triterpene alcohols present in vegetable oils have been identified and determined by HPLC using UV–vis and MS detection after previous derivatization with diphenic anhydride. The alcoholic fraction was obtained by saponification, extraction and TLC (according to the European Union official procedure). Derivatization was performed in tetrahydrofuran in the presence of suspended grinded urea, which increases the reaction rate and yield. Derivatized extracts were chromatographed on a C8 column using gradient elution with acetonitrile/water mixtures containing 0.1% acetic acid, with UV–vis followed by negative-ion mode MS detection. Using linear discriminant analysis of t…
Determination of liposoluble vitamins in cooked meals, milk and milk products by liquid chromatography
2002
A method for the simultaneous determination of liposoluble vitamins in cooked meals was established. Saponification was performed with 50% (w/v) KOH at 80 degrees C, and ascorbic acid was added as antioxidant. The subsequent extraction was carried out with diethyl ether. This was followed by a liquid chromatographic separation on a reversed-phase C18 column with methanol-water (94:6, v/v as the mobile phase. Retinyl acetate was used as the internal standard. The analytical parameters linearity, detection limit (0.19 and 8.33 microg/100 g for retinol and alpha-tocopherol, respectively), precision of the method (RSD=5.24 and 6.99% for retinol and alpha-tocopherol, respectively) and recovery a…
Chemical properties and oxidative stability of Arjan ( Amygdalus reuteri ) kernel oil as emerging edible oil
2017
The oxidative stability, as well as the chemical composition of Amygdalus reuteri kernel oil (ARKO), were evaluated and compared to those of Amygdalus scoparia kernel oil (ASKO) and extra virgin olive oil (EVOO) during and after holding in the oven (170 °C for 8 h). The oxidative stability analysis was carried out by measuring the changes in conjugated dienes, carbonyl and acid values as well as oil/oxidative stability index and their correlation with the antioxidant compounds (tocopherol, polyphenols, and sterol compounds). The oleic acid was determined as the predominant fatty acid of ARKO (65.5%). Calculated oxidizability value and an iodine value of ARKO, ASKO and EVOO were reported as …