A method using (1)H NMR spectroscopy has been developed to quantify simultaneously thirteen analytes in honeys without previous separation or pre-concentration steps. The method has been successfully applied to determine carboxylic acids (acetic, formic, lactic, malic and succinic acids), amino acids (alanine, phenylalanine, proline and tyrosine), carbohydrates (α- and β-glucose and fructose), ethanol and hydroxymethylfurfural in eucalyptus, heather, lavender, orange blossom, thyme and rosemary honeys. Quantification was performed by using the area of the signal of each analyte in the honey spectra, together with external standards.
View Article and Find Full Text PDFA quantitative method for the determination of caffeine, formic acid, trigonelline and 5-(hydroxymethyl)furfural (5-HMF) in soluble coffees by applying the proton nuclear magnetic resonance technique ((1)H NMR) is proposed. Each of these compounds records a singlet signal at the 7.6-9.
View Article and Find Full Text PDFA study has been performed of the conditions for the reaction of histamine with o-phthaldehyde in a flow injection analysis system employing three channels, using an anion-exchange column to eliminate sample matrix interferences. Factorial design was used to determine which operational parameters should be included in the optimization and their optimal values were found. The method developed shows good selectivity for histamine determination in alcoholic beverages.
View Article and Find Full Text PDFThis paper reports a quantitative determination method of (-)-epicatechin in apple juices by measuring of its signal at 7.05 ppm in the (1)H NMR spectrum. It is a direct method that does not need any previous derivatization.
View Article and Find Full Text PDFThis work reports the influence of the high acidity and high phenolic content in apple musts on the development of alcoholic and malolactic fermentations and on the final chemical and microbiological composition of the ciders. Four different musts were obtained by pressing several varieties and proportions of cider apples from the Basque Country (Northern Spain). Specially acidic and phenolic varieties were selected.
View Article and Find Full Text PDFA quantitative determination method of formic acid in apple juices is proposed by means of the proton nuclear magnetic resonance ((1)H NMR) technique. Formic acid gives a singlet signal at the 8.2-8.
View Article and Find Full Text PDFThe low field region (5.8-9.0 ppm) corresponding to aromatic protons and the region 1.
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