title: Food analyses: a new calorimetric method for ascorbic acid (vitamin C) determination.
abstract: The analysis of the ascorbic acid (vitamin C; A.A.) contained in some foodstuff and pharmaceutical samples was performed by a new microcalorimetric method. It uses the oxidation of the vitamin C catalysed by the enzyme ascorbate oxidase (A.O.), which gets the specificity of the reaction. The calibration curve was built under the following operative conditions: 25.00 degrees C, pH 5.6, [A.O.]=11 IU ml(-1), the linearity range is: 3</=A.A.</=270 mg l(-1). The method has been applied to many samples to determine the vitamin C quantity. Each analysis takes about 20 min (the assay time is instead about 5 min, the slow step is due to the time necessary for the calorimeter to return to the operative temperature after washing). No pre-treatments of the samples are requested, unless their solubilisation in buffer. The variations of vitamin C concentration were studied in function of storage time and light exposition. Using a known HPLC assay to compare its reliability on a drug analysis has validated the proposed method.
authors.affiliation: Dipartimento di Chimica, Università degli Studi di Roma 'La Sapienza', P.le Aldo Moro 5, 1-00185 Rome, Italy.
authors.forename: M L
authors.initials: ML
authors.lastname: Antonelli
authors.forename: G
authors.initials: G
authors.lastname: D'Ascenzo
authors.forename: A
authors.initials: A
authors.lastname: Laganà
authors.forename: P
authors.initials: P
authors.lastname: Pusceddu