0000000000536101
AUTHOR
Aarón Escrig-doménech
Capillary Electrophoresis of Free Fatty Acids by Indirect Ultraviolet Detection: Application to the Classification of Vegetable Oils According to Their Botanical Origin
A method for the determination of fatty acids in vegetable oils by capillary electrophoresis with indirect UV–vis detection has been developed. The separation of fatty acids was optimized in terms of Brij surfactant nature and concentration and organic modifier (2-propanol) percentage. The optimal background electrolyte consisted of 10 mM p-hydroxybenzoate, 5 mM Tris at pH 8.8, 80 mM Brij 98, 40% acetonitrile, and 10% 2-propanol. Under these conditions, vegetable oils from five botanical origins (avocado, corn, extra virgin olive, hazelnut, and soybean) were analyzed and the fatty acid contents established. Linear discriminant analysis (LDA) models were constructed using fatty acid peak are…
Determination of the four major surfactant classes in cleaning products by reversed-phase liquid chromatography using serially connected UV and evaporative light-scattering detection.
Abstract A method for the simultaneous determination of the most frequently used surfactant families –linear alkyl benzenesulphonates (LAS), alkyl ether sulphates (AES), fatty alcohol ethoxylates (FAE) and oleins (soaps, fatty acid salts) – in cleaning products, has been developed. The common reversed phase octyl (C8), pentafluorophenyl and biphenyl columns were not capable of separating the anionic LAS and AES classes; however, since only LAS absorbs in the UV, these two classes were independently quantified using a C8 column and serially connected UV and ELSD detection. The best compromise to resolve the four surfactant classes and the oligomers within the classes was achieved with a C8 c…
Single-pump heart-cutting two-dimensional liquid chromatography applied to the determination of fatty alcohol ethoxylates.
Abstract A setup for heart-cutting bi-dimensional liquid chromatography (LC–LC), constructed with a chromatograph provided with a single pump, an auxiliary 6-port 2-position valve (V 6/2 ) and a column selector valve (V CS ), is described. The possible ways of connecting the two valves for LC–LC, namely with V 6/2 first followed by V CS and vice versa, are compared. The possibility of using the setups for preconcentration followed by the backwards transfer of the preconcentrated solutes to the detector or to a second column is also shown. The V 6/2 -first configuration for LC–LC was applied to the characterization of industrial fatty alcohol ethoxylates (FAEs) using UV–vis detection. For th…
Preparation and characterization of octadecyl acrylate monoliths for capillary electrochromatography by photochemical, thermal, and chemical initiation†
Monolithic stationary phases based on octadecyl acrylate for CEC using different initiating systems (UV irradiation, thermal, and chemical initiation) in the presence of lauroyl peroxide as initiator were synthesized. For each initiation mode, the influence of the porogenic solvent composition on both the morphological and electrochromatographic properties of the resulting monoliths was investigated. Under optimal conditions, excellent efficiencies for the photochemically and chemically polymerized monoliths (minimum plate heights of 6.9–10.7 and 6.5–12.6 μm, respectively) were achieved. Thermally initiated columns gave lower efficiency values, permeabilities, and longer analysis times comp…
Derivatization of hydroxyl functional groups for liquid chromatography and capillary electroseparation
The derivatization reactions commonly used to enhance the analytical signal in the HPLC and CE determination of compounds with hydroxyl functional groups are revised. Focus is placed on the determination of compounds having aliphatic alcohols and phenols while lacking other reactive functional groups. The derivatization with acyl chlorides, organic anhydrides, isocyanates and a variety of other approaches, including oxidation of primary and secondary alcohols, sulfonation, esterification with carboxylic acids, and the use of azides, sulfonyl chlorides and other reagents having miscellaneous leaving groups, is covered. Reactions mainly addressed to introduce a chromophore or a fluorophore in…