Acidity changes analysis

Borroto-Esoda K, Miller MD, Arterburn S (2007) Pooled analysis of amino acid changes in the HBV polymerase in patients from four major adefovir dipivoxil chnical trials, J Hepatol 47 492 98... 

The ability of purified PemB to demethylate pectin was confirmed using different techniques. Addition of PemB to a pectin solution (98% methylated) caused an acidification of the reaction medium tested by NaOH titration and by pH indicator colour change. Analysis of the reaction end products by gas chromotography indicated that methanol was formed. These results showed that PemB is able to demethylate pectin, liberating acidic groups and methanol. 

JY Chang. Analysis of phospho-amino acids and amino acid amides at the picomole level using 4 -dimethylaminoazobenzene-4-sulphonyl chloride. J Chromatogr 295 193-200, 1984. 

The ease of oxidation of reduced ascorbic acid is the basis for a simple method of analysis by dye titration (58j. Ascorbic acid as it occurs in citrus juice is in the reduced form. When subjected to oxidation, ascorbic acid changes to the dehydro form. Dehydroascorbic acid has nearly the same physiological activity as the reduced form and is easily converted to the latter. Further oxidation of the dehydroascorbic acid converts it to 2,3-diketo-gulonic acid. This reaction is irreversible, and the oxidized product is devoid of biological activity. These reactions are shown in Figure 2. Nearly 90 percent or more of the vitamin C found in citrus juice and citrus products is in the reduced form (Table X) (59). 

Morse, P.F., Horrobin, D.F., Manku, M.S. etal., Meta-analysis of placebo-controlled studies of the efficacy of Epogam in the treatment of atopic eczema. Relationship between plasma essential fatty acid changes and clinical response, Br. J. Dermatol., 121, 75, 1989. 

More complicated procedures, involving more extensive chemical changes of the acids under analysis, have been developed for special purposes. As an example, the determination of 3-methoxy-4-hydroxymandellic acid in urine, described by Dekirmenjian and... 

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