A Method for the Determination of Small Quantities of Ascorbic Acid and Dehydroascorbic Acid in Turbid and Colored Solutions in the Presence of Other Reducing Substances

Techniques of Histo- and Cytochemistry: A Manual of Morphological and Quantitative Micromethods for Inorganic, Organic and Enzyme Constituents in Biological Materials

“…Ascorbic acid can be titrated with the dye, and dehydroascorbic acid cannot be measured unless it is reduced to ascorbic acid by an agent such as hydrogen sulfide. This reduction is made preferably in a 3% metaphosphoric acid extract buffered to pH 3.5 to 3.7 with citrate (Bessey, 1938) . In macro work the hydrogen sulfide is passed through the solution for about 15 min., and after standing at room temperature for 2 hr., the sulfide is removed by passing wet nitrogen through the liquid for 45-60 min. An application of the procedure to micro work would require the experimental determination of the proper time interval for each of these Standardize the dye soln.…”

Photometric Determination of Reduced and Total Ascorbic Acid

“…To avoid the complications arising from the fact that the reaction between dye and ascorbic acid is not instantaneous, two procedures were adopted by previous investigators for the measurement of the vitamin in biological extracts. One technique (2,15) involves taking readings at 15 and 30 seconds, neglecting the course of the reaction up to the first 15-second reading. However, results presented below indicate that many nonspecific reducing substances react to a considerable extent in 15 seconds, so that extrapolation of the 15-and 30second readings obtained with extracts containing such substances yields erroneously high "ascorbic acid" values.…”

“…The manipulations required 2 hours, but at all times the temperature was maintained at less than 0°C. Photometric analysis for c In preparation of potato chips a 3.5-fold concentration of solids occurred.…”

Συγκριτικός Προσδιορισμός Του Ασκορβικού Και Δεϋδροασκορβικού Οξέος Στο Πλάσμα Και Τα Λευκά Αιμοσφαίρια Με Τη Μέθοδο Της Υγρής Χρωματογραφίας Υψηλής Απόδοσης

“…Κατά την ανάλυση με 2,6-διχλωροινδοφαινόλη, το AA ανάγει την χρωμοφόρο ουσία, προκαλώντας μείωση της απορρόφησης στα 520 nm (Omaye et al, 1979, Bessey, 1938, Henry et al, 1974. Σε pH=3-4,5 παρουσία Ν 2 το χρώμα δεν επηρεάζεται από οξειδωμένους μεταβολίτες του AA (Tangney, 1988).…”

“…Υπάρχουν πολλά μειονεκτήματα της μεθόδου με την 2,6-διχλωροινδοφαινόλη. Η τεχνική δεν είναι ευαίσθητη, με ένα αναφερόμενο όριο ανίχνευσης 34nmol/δείγμα (Bessey, 1938). Η έλλειψη εξειδίκευσης είναι ένα άλλο πρόβλημα.…”