Nonaqueous acid-base titration titrant

Many pharmaceutical compounds are weak acids or bases that can be analyzed by an aqueous or nonaqueous acid-base titration examples include salicylic acid, phenobarbital, caffeine, and sulfanilamide. Amino acids and proteins can be analyzed in glacial acetic acid, using HCIO4 as the titrant. For example, a procedure for determining the amount of nutritionally available protein has been developed that is based on an acid-base titration of lysine residues. ... 

Potcntiomctric Titrations In Chapter 9 we noted that one method for determining the equivalence point of an acid-base titration is to follow the change in pH with a pH electrode. The potentiometric determination of equivalence points is feasible for acid-base, complexation, redox, and precipitation titrations, as well as for titrations in aqueous and nonaqueous solvents. Acid-base, complexation, and precipitation potentiometric titrations are usually monitored with an ion-selective electrode that is selective for the analyte, although an electrode that is selective for the titrant or a reaction product also can be used. A redox electrode, such as a Pt wire, and a reference electrode are used for potentiometric redox titrations. More details about potentiometric titrations are found in Chapter 9. 

The purpose of this chapter is to consider the preparation and standardization of acids and bases and to review some of the important applications of acid-base titrations in aqueous and nonaqueous systems. For end points to be detected most precisely, the pH in the vicinity of the equivalence point should change sharply. For this reason a solution of strong acid or base is chosen as titrant whenever possible. 

Controlled-current coulometry (coulometric titration) can be utilized to determine not-easily oxidizable (or reducible) analytes of different applications via acid-base, precipitation, com-plexation titrations, etc. Furthermore, it benefits short analysis time and small amount determination [2]. Dzudovic et al. [21] reviewed some studies employing acid-base titrations for the determinations of non-aqueous or water-insoluble compounds (organic and inorganic). Typically, acidimetric titrations were undertaken coulometrically based on the EF liberated by the oxidation of the introduced H2O. Coulometric titrations of bases in nonaqueous solvent were performed using anodic depolarizers (titrants) to generate as a source. On the other hand, coulometrically atkalimetric... 

V. E. Petrakovich, O. M. Podurovskaya, and I. Ya. Turyan, Russ. J. Anal. Chem., 20, 863 (1965). Comparison of oxidized Platinum and Glass Indicator Electrodes for Acid-base Titrations. The Effect of Nonaqueous Solvents, the Nature of the Titrant and of Different Additives. 

Many cationic surfactants can be determined by direct acid-base titration in nonaqueous solvents according to general methods for determination of amines. Usually, perchloric acid titrant is used in a solvent of glacial acetic acid. Since such titrations are in no way specific for surfactants, they can only be used for solutions in which there are no unknown components. Details may be found in standard texts on nonaqueous titration. 

I would now like to consider the titration of acidic compounds in nonaqueous solutions. If you wish to titrate an acid in nonaqueous solution, you should choose a solvent that is not acidic and a titrant that is as strong a base as possible. The paper that really aroused people s imagination and created a lot of interest was the one published by Moss, Elliot, and Hall in 1948, in which they introduced ethylenediamine as a solvent. This compound certainly doesn t have any acidic properties and these authors showed that you can titrate phenol, which is normally too weak to titrate as an acid. In recent years, however, the trend has been away from the use of strongly basic solvents because they have a leveling effect on many bases and they are somewhat unpleasant to handle. Solvents now in use are pyridine, which is an inert solvent and a very weak base, acetonitrile, and acetone. Acetone and certain other ketones are surprisingly good. Recently we have done some work with tertiary butyl alcohol, an excellent solvent for certain cases. Sodium or potassium hydroxide can be used as tltrants, but these are not particularly... 

The majority of titrations involving basic analytes, whether conducted in aqueous or nonaqueous solvents, use HCl, HCIO4, or H2SO4 as the titrant. Solutions of these titrants are usually prepared by diluting a commercially available concentrated stock solution and are stable for extended periods of time. Since the concentrations of concentrated acids are known only approximately,the titrant s concentration is determined by standardizing against one of the primary standard weak bases listed in Table 9.7. 

The NH3 is removed by distillation and titrated with HCl. Alternatively, N03 can be titrated as a weak base in an acidic nonaqueous solvent such as anhydrous acetic acid, using HCIO4 as a titrant. 

When titrating very weak acids, such as phenols, enols, or sulfonamides, in nonaqueous solvents, the endpoint detection is easier and more accurate when stronger bases are used as titrants. This is because both the potential jump in a potentiometric titration and the color change in a visual titration become more pronounced. 

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