Exploiting flow-based separation techniques for sample handling in wine analysis

Wine is a fermented product consumed in a large scale all over the world that therefore has a large impact both economic and food safety terms. The analytical control of the final product is thus of high importance; it is not a simple task given that the chemical composition of wine is very variable and complex. Consequently, there is always the need for some sample pre-treatment prior to analysis. Flow-based analyses are known for their efficiency in sample manipulation and can be easily coupled to other techniques, such as separation techniques, namely membrane-based or extraction procedures. This possibility is an important step when dealing with complex matrices, such as wine samples. This review presents the state of the art of the methodologies that were developed using flow-based systems coupled to separation devices applied to wine analysis, namely membrane-based, solid, and liquid phase extraction and low pressure chromatography separations.info:eu-repo/semantics/acceptedVersio

Sequential injection-LOV format for peak height and kinetic measurement modes in the spectrophotometric enzymatic determination of ethanol: Application to different alcoholic beverages

The objective of this work was to make a contribution to study the potential of the sequential injectionlab-on-valve (SI-LOV) format for the miniaturization of enzymatic assays, by using different measurement modes (peak height and initialrate-based measurement). A LOV system was developed for the enzymatic assay of ethanol in beverages, based on the conversion of ethanol to acetaldehyde by alcohol dehydrogenase, using spectrophotometric detection. The use of the kinetic-based approach permits the applicability of the enzymatic determination to samples with intrinsic absorption, with a higher determination throughput. A linear dynamic application range up to 0.040% (v/v)was achieved for both initial rate and for the peak height measurement, with good repeatability (R.S.D. < 5.0% and <1.0%, respectively). Enzyme, NAD+, buffer and sample consumption per assay were 0.12U, 0.066 mg, 150 and 15µL, respectively. The determination rate achieved was 37 and 27 determinations h−1 for the initial rate and for the peak height measurement, respectively. The results obtained for several alcoholic beverages, including a certified sample material, were not statistically different from those obtained by the reference procedures.info:eu-repo/semantics/acceptedVersio

Sequential injection lab-on-valve system for the on-line monitoring of hydrogen peroxide in lens care solutions

A sequential injection lab-on valve (SI-LOV) method for the enzymatic determination of hydrogen peroxide was developed. The spectrophotometric assay is based on the reaction between hydrogen peroxide and ABTS (2,2′-Azino-bis(3-Ethylbenzothiazoline 6-sulfonic acid)) in the presence of the enzyme HRP (horseradish peroxidase). The produced oxidized ABTS is measured at 410 nm. The sample consumption was 15 μL/assay and the consumption of HRP and ABTS was 34.6 mg L−1 and 0.06 g L−1, respectively with a determination rate of 45 h−1. Relative deviations lower than 9.0% were found when the results were compared to those obtained by the reference procedure in the analysis of bleaches and disinfection solutions for contact lenses. With the incorporation of an in-line dilution (dialysis) process,was possible to attain a response range up to 342 mg L−1 of hydrogen peroxide. The developed methodwas applied to monitor on-line of the disinfection–neutralization process of contact lenses. The study of two different one-step systems for cleaning contact lenses demonstrated that the neutralization of the hydrogen peroxide is completed within 6 h as recommended by the manufactures. The developed flow method was proved to be a useful tool for monitoring the dynamic process of disinfection–neutralization.info:eu-repo/semantics/acceptedVersio

Sequential injection lab-on-valve system for the determination of the activity of peroxidase in vegetables

Horseradish peroxidase (HRP) has been broadly used and investigated for many analytical purposes; it is an enzyme that catalyzes the reduction of hydrogen peroxide in the presence of a reducing compound. The objective of this work was to develop a methodology for the spectrophotometric determination of the activity of peroxidase in vegetable extracts using a flow method with a sequential injection lab-on-valve format. The developed system is based on the reaction between hydrogen peroxide (H2O2) and 2,2-azinobis(3-ethylbenzothiazoline-6)sulfonic acid (ABTS) catalyzed by the enzyme (HRP). The method presented a sample consumption of 15 μL per assay and a consumption of ABTS and H2O2 of 24 μg and 12 μg per assay, respectively. It was also possible to monitor online the thermal inactivation of peroxidase at different temperature ranges.info:eu-repo/semantics/publishedVersio

Exploiting the bead injection LOV approach to carry out spectrophotometric assays in wine: application to the determination of iron

A sequential injection lab-on-valve (SI-LOV) system was used to develop a new methodology for the determination of iron in wine samples exploiting the bead injection (BI) concept for solid phase extraction and spectrophotometric measurement. Nitrilotriacetic Acid (NTA) Superflow resin was used to build the bead column of the flow through sensor. The iron (III) ions were retained by the bead column and react with SCN- producing an intense red colour. The change in absorbance was monitored spectrophotometrically on the optosensor at 480 nm. It was possible to achieve a linear range of 0.09-5.0 mg L-1 of iron, with low sample and reagent consumption; 500 mu L of sample, 15 mu mol of SCN-, and 9 mu mol of H2O2, per assay. The proposed method was successfully applied to the determination of iron in wine, with no previous treatment other than dilution, and to other food samples.info:eu-repo/semantics/acceptedVersio

Merging zones approach in a flow-based platform for the determination of the total protein content in microbiological samples

info:eu-repo/semantics/publishedVersio

Protein-phenolic interaction as a strategy to reduce the precursors of volatile phenolics in wine

info:eu-repo/semantics/publishedVersio

Analytical microsystem for the spectrophotometric determination of titratable acidity in wines

info:eu-repo/semantics/publishedVersio