Search results for " Analytical"
showing 10 items of 1453 documents
Scopolamine analysis in beverages: Bicolorimetric device vs portable nano liquid chromatography
2021
Abstract Scopolamine (SCP) is often involved in sexual assaults and robberies, particularly in recreational environments. Therefore, analytical tools are required for the analysis of this compound amenable for the field. In this work, a sensor for SCP is described based on the entrapment of KMnO4 into polydimethylsiloxane (PDMS). The possibility of using KMnO4 in combination with the reagent 1,2-naphtoquinone-4-sulfonate (NQS) giving a double sensor acting as a bicolorimetric device is also demonstrated. In contact with the sample, the PDMS composite delivers MnO4−, which reacts rapidly with SCP under basic conditions causing a change of the color of the solution that can be related to the …
Date-rape evidence through fast determination of γ-butyrolactone in adulterated beverages.
2021
Abstract An infrared spectroscopy (IR) based methodology has been developed to determine γ-butyrolactone (GBL) in adulterated beverages. The proposed method permits the direct screening of GBL in beverages and involves a minimum sample treatment requiring less than 2 min for quantitative determination of GBL. Sensitivity of IR method was improved by using liquid-liquid extraction (LLE) providing detection limits of 0.023 mg g−1. Accuracy of the proposed methodology was evaluated through the analysis of soft beverages and alcoholic cocktails spiked with GBL at concentration levels ranging from 0.075 to 10 mg g−1 providing recovery values from 91 to 100%. GBL was determined in twelve blind-sp…
Application of finger span cross modality matching method (FSCM) by naive assessors for olfactometric discrimination of Gewürztraminer wines
2002
Abstract A gas-chromatography-olfactometric detection (GCO) using a direct estimation of odor intensities with the finger span (FSCM) was used to establish aroma profiles of three wines of gewurztraminer from different ‘terroirs’ of the Alsace region. The GCO-FSCM analyses of their hydroalcoholic wine extracts were performed using a group of untrained assessors. Forty-four olfactory signals were perceived by at least four assessors out of six and their intensities were scored in triplicate in each of the three wine extracts, amongst which ten of them were found discriminant between wines. The reliability of each assessor was studied on the basis of the finger span estimation repeatability, …
Application of high Power ultrasounds during red wine vinification
2017
[EN] Wine colour is one of the main organoleptic characteristics influencing its quality. It is of special interest in red vinifications due to the economic resources that wineries have to invest for the extraction of the phenolic compounds responsible for wine colour, compounds that are mainly located inside the skin cell vacuoles, where the volatile compounds are also found. The transfer of phenolic compounds from grapes to must during vinification is closely related to the type of grapes and the winemaking technique. During traditional winemaking, grapes are crushed and skin macerated for several days, with pumps overs to facilitate the colour extraction. To increase this extraction, som…
Optimal Conditions for the Formation of Sotolon from .alpha.-Ketobutyric Acid in the French "Vin Jaune"
1995
Sotolon (3-hydroxy-4,5-dimethyl-2(5H)-furanone) is a key flavor compound in the French flor-sherry Vin Jaune. Sotolon in Vin Jaune (120-268 microgram/L) is produced during the development of yeast film over a period of 6 years. In a synthetic medium resembling wine, the formation of sotolon was studied for different organic acids and acetaldehyde. Then, sotolon was quantified by HPLC on a Lichrospher 100 Diol column. Under the conditions of temperature, pH, and alcoholic content similar to the ageing of wine in barrels, sotolon was formed by a purely chemical mechanism from alpha-ketobutyric acid and acetaldehyde. The formation of sotolon increases by increasing temperature and decreasing p…
Perceptual interactions between fruity and woody notes of wine
2004
The quantitative olfactory interactions in three binary mixtures of wine aroma compounds were studied. For the first two mixtures, whisky lactone (woody note) was mixed separately with two esters (fruity note), ethyl butyrate and isoamyl acetate. For the third mixture, guaiacol (woody note) was mixed with ethyl butyrate (fruity note). Perceived odour intensity of 24 stimuli (four supra-threshold concentration levels of two compounds and the respective 16 mixtures) were evaluated in five replications, by a trained panel of 13 subjects. The results showed that for the three binary mixtures studied, quantitative perceptual interactions were non-level independent, non-symmetrical, and reached t…
Influence of bentonite fining on protein composition in wine
2017
Abstract Bentonite is the only fining agent which can stabilize wine and prevent protein haze formation after bottling. Currently many approaches are used to find an alternative because of bentonite's negative influence on color and aroma compounds. Nevertheless, the interaction of bentonite with wine proteins is not fully understood. Therefore, we analyzed the influence of a NaCa-combined bentonite on the protein content and composition of different wines showing a partial selectivity on protein adsorption. For example, glycosylated proteins were not removed by bentonite in notable amounts. Performing mass spectrometry we were able to demonstrate that 96% of class IV chitinase was adsorbed…
Searching the most appropriate sample pretreatment for the elemental analysis of wines by inductively coupled plasma-based techniques.
2008
Different sample preparation methods were evaluated for the simultaneous multielement analysis of wine samples by inductively coupled plasma optical emission spectrometry (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS). Microwave-assisted digestion in closed vessel, thermal digestion in open reactor, and direct sample dilution were considered for the determination of Li, Be, Na, Mg, Al, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Sr, Y, Mo, Cd, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Tl, Pb, and Bi in 12 samples of red wine from Valencia and Utiel-Requena protected designation of origin. ICP-MS allows the determination of 17 elements in most…
The use of core-shell high-performance liquid chromatography column technology to improve biogenic amine quantification in wine
2015
BACKGROUND HPLC column technology has been improved, providing better resolution of closely eluting compounds, better analyte sensitivity, and shorter analysis times. The core-shell technology columns offer a faster analysis through the use of shorter columns without compromising resolution. The aim of this work was to improve the methods for determination of biogenic amines (BAs) in wine using the new HPLC PFP core-shell column technology. RESULTS Two different elution programs were designed to quantify BAs with the core-shell PFP column. Program I flow rate was 2 mL min−1. The total elution time was 10 min. In elution program II, the flow rate was 0.8 mL min−1 and the total elution time w…
Multi-scale optimisation vs. genetic algorithms in the gradient separation of diuretics by reversed-phase liquid chromatography
2019
Abstract Multi-linear gradients are a convenient solution to get separation of complex samples by modulating carefully the gradient slope, in order to accomplish the local selectivity needs for each particular solute cluster. These gradients can be designed by trial-and-error according to the chromatographer experience, but this strategy becomes quickly inappropriate for complex separations. More evolved solutions imply the sequential construction of multi-segmented gradients. However, this strategy discards part of the search space in each step of the construction and, again, cannot deal properly with very complex samples. When the complexity is too large, the only valid alternative for fi…