Salt titration method

The salt titration method [666] is a modification of the salt addition method. A portion of salt is added to a dispersion, and the ApH is recorded. When ApH > 0, base is added to shift the pH to an even higher value. When ApH < 0, acid is added to shift the pH to an even lower value. Once a constant pH has been established, a new portion of salt is added, and ApH is recorded again. The series of salt additions followed by acid or base additions is continued until ApH = 0. The advantage of the salt titration method as compared with the classical salt addition method is that only one portion of dispersion is used. Thus, PZC determination requires a smaller amount of solid and only one reaction vessel. Moreover, a series of measurements (e.g., at different temperatures or at different concentrations of a nonaqueous co-solvent) can be carried out with the same portion of solid, and effects due to a difference in surface properties between different portions of solid are avoided. The number of consecutive salt additions in the salt titration method is limited, because the sensitivity of ApH to an addition of the same amount of salt decreases as the initial salt concentration increases. 

Tan, W.F. et al., Determination of point of zero charge of manganase oxides using an improved salt titration method, in 18th World Congress of Soil Science, 2006, cited after [2906]. 

The fermentation-derived food-grade product is sold in 50, 80, and 88% concentrations the other grades are available in 50 and 88% concentrations. The food-grade product meets the Vood Chemicals Codex III and the pharmaceutical grade meets the FCC and the United States Pharmacopoeia XK specifications (7). Other lactic acid derivatives such as salts and esters are also available in weU-estabhshed product specifications. Standard analytical methods such as titration and Hquid chromatography can be used to determine lactic acid, and other gravimetric and specific tests are used to detect impurities for the product specifications. A standard titration method neutralizes the acid with sodium hydroxide and then back-titrates the acid. An older standard quantitative method for determination of lactic acid was based on oxidation by potassium permanganate to acetaldehyde, which is absorbed in sodium bisulfite and titrated iodometricaHy. 

Specifications, Analysis, and Toxicity. Dicyandiamide is identified quaHtatively by paper chromatography and quantitatively by ultraviolet spectrometry of the chromatogram. More commonly, total nitrogen analysis is used as a purity control or the dicyandiamide is converted by hydrolysis to guanylurea, which is determined gravimetrically as the nickel salt (50). Methods based on the precipitation of silver dicyandiamide picrate are sometimes used (51). Dicyandiamide can also be titrated with tetrabutylammonium hydroxide ia pyridine solution. Table 4 gives a typical analysis of a commercial sample. Dicyandiamide is essentially nontoxic. It may, however, cause dermatitis. 

Metal Content. Two common analytical methods for determining metal content are by titration and by atomic absorption spectrophotometry (aas). The titration method is a complexiometric procedure utilizing the disodium salts of ethylenediaminetetraacetic acid (EDTA). The solvent, indicator. 

For the estimation of ephedrine in its salts or simple solutions, titration methods and a Kjeldahl estimation have been described by various authors. The formation of iodoform from ephedrine has been proposed as a method of estimation by Sanchez, and biological methods have been used by several authors. ... 

Wang and Pek [185] have described a simple titration method applicable to the analysis of cationic surfactants in sea water. Methyl orange and azure A were used as primary dye and secondary dye, respectively. The method is free from interference by high levels of inorganic salts in sea water. 

In contrast to aspirin itself, the U.S.P. monograph for aspirin tablets has undergone considerable changes. For some reason, U.S.P. does not use the ferric salt test for free salicylic acid, as does the British Pharmacopeia of 1973. Apparently, certain excipients such as citric and tartaric acid interfere with this reaction.77 Already in 1913, a double titration method was developed78 which was made an official method in 1926.79 This method was used as the assay method when the aspirin tablets monograph was introduced into U.S.P. XII in 1942. 

Anions may be measured best by ion chromatography, using appropriate anion exchange resin columns that are available commercially. Salts may be diluted for such measurements. Ion-selective electrode methods also yield satisfactory results at trace concentrations. Numerous colorimetric methods are reported in literature. They are susceptible to erroneous results when impurities are present. Many titration methods are available in analytical chemistry. They may be applied successfully to measure certain anions, oxidizing and reducing substances, acids, and bases. 

Non-aqueous titration methods have been described for the rapid determination of chlorpromazine and its hydrochloride salt by titration with perchloric acid [54]. The titration is performed after the proscribed extraction from suppository, tablet, and ampoule dosage forms is completed. 

The method of Koval chuk et al. was applied in the determination of procaine [84], These authors have also developed another alkalimetric two-phase titration method for determination of the salts of organic bases, including procaine hydrochloride [85]. A solution of the base salt was mixed with 2 mL chloroform and 2 drops of 0.15% methylene blue solution, and the mixture titrated with 0.02 to 0.1 M sodium hydroxide with shaking. At the endpoint, the chloroform layer becomes pink-violet. 

Chen and Gao studied the use of oscillopolarographic titration, and reported a direct titration of the salts of weak organic bases (or acids) in aqueous solution [61]. In their work, they included the determination of procaine by an oscillopolarographic titration method. 

Several crops of crystals are now taken by evaporating the aqueous solution to the saturation point on a hot plate with stirring, then cooling. Each crop is dried for 2 hours at 100° and analyzed for unsaturation by the bromate-bromide titration method (Note 10). The first two crops usually total about 380 g. (based on 300 g. of sulfur trioxide), 49% yield, and are about 95% pure by titration. They may be further purified by one recrystallization from water, with about 80% recovery of 99+% pure salt. 

The preferred method for analyzing chlorinated isocyanuric acids and their salts is the iodometric titration (J) The main limitation of the iodometric titration method is sample size generally one would need a minimum of 100 milligrams for titrating either compound. For industrial hygiene samples, this is a problem because sample weights are usually smaller by a factor of 20,... 

Phenanthrene was analyzed directly by fluorescence with excitation at 365 nm and emission at 394 nm and quantified by comparison to a standard curve. 5-Chlorouracil was analyzed directly by absorbance at 270 nm. Attempts to determine 5-chlorouracil as the pyrolysis product of its tetramethylammonium salt (11) were unsuccessful. Hypochlorite was determined by the ferrous-N,N-diethyl-p-phenylenediamine titration method (12). 

Potassium permanganate oxidises arsenious acid rapidly and quantitatively in the presence of a trace of potassium iodide, which acts catalytically.7 The reaction takes place in the presence of mineral acid and the use of an indicator or of sodium bicarbonate is unnecessary. The titration may be carried out at any temperature up to 95° C. A slight correction is necessary for the oxidation of the iodide other iodides are less effective than the potassium salt. This method is comparable in accuracy with the iodometric method. 

Salt (NaCl) AOAC 975.20 (2005) Quantab strip chloride titration method (based on Mohr s titration)... 

Indirect Titration (Method B). A weighed sample of salt was added to a flask containing methanol and a known excess of aqueous sodium hydroxide solution. The mixture was stirred and warmed on a hot plate for 1 h. After cooling, the amount of excess hydroxide present was determined by titration with standard aqueous hydrochloric acid. The titration was monitored using a pH electrode and meter, and the end point was determined from the resulting titration curve. 

The results with Cu - and Cu -TSMs (27) are also shown in Table III. Cu -TSM was obtained similarly to Cu -TSM using the Cu(I) ammine complex salt in the ion-exchange reaction. Cu -TSM, copper supported on TSM, was prepared by calcination and subsequent hydrogen reduction of an oligomeric cupric hydroxide intercalate, which had been obtained by precipitating the hydroxide into the interlayer spaces of TSM after the titration method developed by Yamanaka and Brindley (8). The catalytic activity of Cu -TSM is so poor as to be less than one-tenth of that of Cu -TSM, although the molar content of Cu is about twice as high. Because a weak sig-... 

The European and British Pharmacopoeias [2] use the mercurimetric titration assay described in Section 6.2.2 for assay of both the trihydrate and sodium salt. The method is also specified for determination of degradation products in the sodium salt monograph. 

The USP XXI (3) describes a non-aqueous titration method for the assay of hyoscyamine and its salts (the hydrobromide and the sulfate) ... 

Argentometric titration method has been applied to the determination of sulfonamide mixtures. The sulfonamides are quantitatively precipitated by the addition of excess standard silver nitrate solution, the precipitated silver salts removed by filtration, and the excess silver nitrate titrated with standard ammonium thiocyanate using ferric alum as indicator (32). 

Salts are the products of the acid-base neutralisation reaction. The salts used most in textile wet processes are common salt (NaCl, sodium chloride) and Glauber s salt (Na SO, sodium sulphate). The content analysis of salts is usually conducted by using a precipitation titration method which may be followed by fdtering and weighing procedures to obtain the final results. 

Since many compounds are weak acids or bases, their solubility will then be a function of pH. Figure 6.10 shows the pH-solubilty curve for a hydrochloride salt with pKas at 6.58 and 8.16. When the acid-base titration method (Serrajudden and Mufson 1985) was used, the solubility curve showed a minimum between pH 6 and 8. Below this pH region, the solubility... 

A simple method for estimating the pH-solubility relationship of bile acids and salts is to carry out aqueous acidometric titration of a bile salt in water with a stronger mineral acid [5,35], Once the molarities of bile salt and mineral acid are known, the titration curves provide a direct measurement of equivalence, equilibrium and metastable pH values, the pH at which precipitation of the HA species occurs (pHpp,), an estimate of the solubilities of the HA species in water (if the system is < CMC) or in water plus micelles (if the system is > CMC) and a calculation of the apparent pK (pATg). The methods, results and interpretation of such titration curves for the common bile salts, titrated with HCl, have been described in detail elsewhere [5,6]. 

Heux et al. (2000) found that after partial deacetylation (<50%), the product of chitin becomes soluble in acidified water. Therefore, chitosan is characterized by its DA, which is the average mole fraction/percentage of A-acetyl-D-glucosaminc units within the macromolecular chain (Desbrieres, 2002). Alternatively, Heux et al. (2000) calculated DA by measuring all carbonyl or methyl groups divided by the integral of all the carbon atoms in the backbones. The DD may be determined by a titration method in which chitosan is dissolved in 0.1% acetic acid to form a 0.01% solution. This is followed by titration with 0.0025 N poly (vinyl sulfate) potassium salt (PVSK) with 1% toluidine blue (TBO) as an indicator. The acetyl content of... 

Ethanol This is determined by oxidation with K2Cr207, followed by titration with Fe (NH4)2(S04)2 6H20-Mohr salt [13] and using a Waters high performance liquid chromatography (HPLC), an ion exchange Shodex column, at 80°C, refraction index detection, at 34°C, elution with Milli-Q water, flow rate of 1.0 ml/min. All samples were analyzed using the titration method. HPLC was used to confirm the results obtained with the titration method. The two methods led to very similar results. 

Sakurai, K., Ohdate, Y., Kyuma, K., 1988. Comparison of salt titration and potentiometric titration methods for the determination of zero point of charge. Soil Sci. Plant Nutr. 34, 171-182. 

Badoz-Lambling and Bardin ° have reported the stability constants of several silver-salts in nitromethane at 20 C. The results, obtained by the potentiometric titration method, are given in Table 2.7.24. From this table it is seen that most AgA g species are stable. No soluble complexes were found for the BrOg and (CeH5)4B anions. 

The mentioned method seems to have no wide usage for studying behavior of oxides in molten salts, solubility studies by isothermal saturation and potentiometric titration methods are more precise and informative. 

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