Ascorbic acid with sulfites

Reports continue in the 1970s on the ascorbic acid treatment of beer (658-669). Use of ascorbic acid with sulfites shows favorable results on beer quality as described by Scriban and Stienne (662) and Master et al. (669). Analyses of imported beer indicate addition of ascorbates even if not so labeled (665). Kormomicka (667) reported 3 g/hL addition of ascorbic acid extended beer quality 89 days 5 g/hL, 108 days. Baetsle (666), on an industrial scale, found 2 g/hL preserved color and flavor of beer during storage for 66 days. 

H. R. Wagner, and M. J. McGarrity, The use of pulsed amperomctry combined with ion-exclusion chromatography for the simultaneous analysis of ascorbic acid and sulfite, J. Chromatogr., 546. 119, 1991. 

Miura, Y. Hatakeyama, M. Hosino, T. Haddad, P.R. Rapid ion chromatography of L-ascorbic acid, nitrite, sulfite, oxalate, iodide and thiosulfate by isocratic elution utilizing a postcolunm reaction with cerium(IV) and fluorescence detection. J. Chromatogr. A, 2002, 956,11-8A. 

Chromate(VI) Reduction with arsenate(III), ascorbic acid, hydrazine, hydroxylamine, sulfite, or thiosul-... 

Because of the time and expense involved, biological assays are used primarily for research purposes. The first chemical method for assaying L-ascorbic acid was the titration with 2,6-dichlorophenolindophenol solution (76). This method is not appHcable in the presence of a variety of interfering substances, eg, reduced metal ions, sulfites, tannins, or colored dyes. This 2,6-dichlorophenolindophenol method and other chemical and physiochemical methods are based on the reducing character of L-ascorbic acid (77). Colorimetric reactions with metal ions as weU as other redox systems, eg, potassium hexacyanoferrate(III), methylene blue, chloramine, etc, have been used for the assay, but they are unspecific because of interferences from a large number of reducing substances contained in foods and natural products (78). These methods have been used extensively in fish research (79). A specific photometric method for the assay of vitamin C in biological samples is based on the oxidation of ascorbic acid to dehydroascorbic acid with 2,4-dinitrophenylhydrazine (80). In the microfluorometric method, ascorbic acid is oxidized to dehydroascorbic acid in the presence of charcoal. The oxidized form is reacted with o-phenylenediamine to produce a fluorescent compound that is detected with an excitation maximum of ca 350 nm and an emission maximum of ca 430 nm (81). 

CuCl, especially in a single crystal form, is extensively used as an optical material for its special optical properties. Orel et al. [2] first proposed a new method to obtain CuCl particles by the reduction of Cu with ascorbic acid. Several dispersants were used in the reduction and monodispersed CuCl particles can be obtained by selecting the proper dispersant and reduction conditions. In this work, the above method was used to modify the traditional process of CuCl preparation, namely, by reducing the Cu " with sodium sulfite to obtain the highly active CuCl catalyst to be used in the direct process of methylchlorosilane synthesis. 

Iron-free ferrioxamine B ( Desferal", Ciba Pharmaceutical Company, Sum-mitt, New Jersey) reacts rapidly with ferrous ion, especially at neutral pH, forming the ferric chelate. This transition is blocked by mercaptoacetic acid, hydrosulfite and thiosulfate but not by weaker reducing agents such as ascorbic acid, hydroxylam-ine and sulfite (Nature 205, 281, 1965). 

A coulometric titration method was introduced for sequential determination of sulfite, thiosulfate and ascorbic acid (1) in solutions containing sulfite-thiosulfate or sulfite-ascorbic acid couples. Formaldehyde or acetaldehyde can be used to mask the sulfite component. Two sequential measurements of coulometric time, one for both components in the mixture and one for the sample solution in which sulfite is masked, can be used to determine the concentrations of sutfite-thiosulfate and sulfite-ascorbic acid couples. The method is linear for 0.5-60 p,M 1 in the presence of 0.44-13 (xM sulfite, with RSD 0.1-4% and current efficiency of ca 98.0%. The method can be used for determination of the presence of sulfite and 1 in real sample matrices such as mineral waters and vitamin C tablets . 

When no dechlorination chemical was added, the dissolved oxygen concentration of the released water decreased from an initial concentration of 11 by less than 0.3 mg/L after traveling 450 ft in one test. When stoichiometric amounts of dechlorination chemicals were added, the DO decreased by 1.18,0.3,0.55, and 0.5 mg/L in the presence of sodium metabisulfite, sodium sulfite, sodium thiosulfate, and calcium thiosulfate, respectively. When twice the stoichiometric amounts of dechlorination chemicals were added, the dissolved oxygen concentration decreased hy 1, 0.9, 0.9, and 0.7 mg/L, respectively, in the presence of these chemicals. With the addition of stoichiometric concentrations of ascorbic acid and sodium ascorbate, the DO of the water increased by 0.3 mg/L, after a travel of 450 ft. When twice the stoichiometric concentrations of these chemicals were used, the DO decreased hy 0.2 mg/L. 

Ascorbic acid browning is also inhibited by the addition of sulfite (Wedzicha and McWeeny, 1974). The same holds for polyphenol oxidase-catalyzed oxidation of natural phenols in fruit. The mechanism of the inhibition is by reaction of oquinone intermediates with sulfite, which leads to nonreactive sulfocatechols (Wedzicha, 1995). 

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