Fluorescent sensing layer for the determination of L-malic acid in wine.

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Gallarta F, Sainz FJ, Saenz C

Fluorescent sensing layer for the determination of L-malic acid in wine.

Anal Bioanal Chem. 2007 Mar;387(6):2297-305. Epub 2007 Jan 4.

PubMed ID

17203264 [ View in PubMed

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Abstract

An enzymatic method for determining L-malic acid in wine based on an L-malate sensing layer with nicotinamide adenine dinucleotide (NAD+), L-malate dehydrogenase (L-MDH) and diaphorase (DI), immobilized by sol-gel technology, was constructed and evaluated. The sol-gel glass was prepared with tetramethoxysilane (TMOS), water and HCl. L-MDH catalyzes the reaction between L-malate and NAD+, producing NADH, whose fluorescence (lambdaexc=340 nm, lambdaem=430 nm) could be directly related to the amount of L-malate. NADH is converted to NAD+ by applying hexacyanoferrate(III) as oxidant in the presence of DI. Some parameters affecting sol-gel encapsulation and the pH of the enzymatic reaction were studied. The sensing layer has a dynamic range of 0.1-1.0 g/L of L-malate and a long-term storage stability of 25 days. It exhibits acceptable reproducibility [sr(%) approximately 10] and allows six regenerations. The content of L-malic acid was determined for different types of wine, and polyvinylpolypyrrolidone (PVPP) was used as a bleaching agent with red wine. The results obtained for the wine samples using the sensing layer are comparable to those obtained from a reference method based on UV-vis molecular absorption spectrometry, if the matrix effect is corrected for.

DrugBank Data that Cites this Article

Drug Targets

Drug	Target	Kind	Organism	Pharmacological Action	Actions
NADH	Malate dehydrogenase, mitochondrial	Protein	Humans	Unknown	Not Available	Details