Titratible acidity

The most common strong base for titrating acidic analytes in aqueous solutions is NaOH. Sodium hydroxide is available both as a solid and as an approximately 50% w/v solution. Solutions of NaOH may be standardized against any of the primary weak acid standards listed in Table 9.7. The standardization of NaOH, however, is complicated by potential contamination from the following reaction between CO2 and OH . 

Yogurt is manufactured by procedures similar to buttermilk. Milk with a fat content of 1—5% and soHds-not-fat (SNF) content of 11—14% is heated to ca 82°C and held for 30 minutes. After homogenization the milk is cooled to 43—46°C and inoculated with 2% culture. The product is incubated at 43°C for three hours in a vat or in the final container. The yogurt is cooled and held at <4.4° C. The cooled product should have a titratable acidity of not less than 0.9% and a pH of 4.3—4.4. The titratable acidity is expressed in terms of percentage of lactic acid [598-82-3] which is deterrnined by the amount of 0.1 AiNaOH/100 mL required to neutralize the substance. Thus 10 mL of 0.1 AiNaOH represents 0.10% acidity. Yogurts with less than 2% fat are popular. Fmit-flavored yogurts are also common in which 30—50 g of fmit are placed in the carton before or with the yogurt. 

The chemical analyses tabulated ia this article ideatify "alkalinity" as a property of the water rather than a simple constituent. Alkalinity has been more broadly defined as "capacity for acid neutralization" (12,13). Common practice ia water analysis is to report alkalinity ia terms of bicarboaate and carbonate concentrations, although other ionic species also may contribute by reacting with the titrating acid. 

The other analytical methods necessary to control the typical specification given in Table 5 are, for the most part, common quality-control procedures. When a chemical analysis for purity is desired, acetylation or phthalation procedures are commonly employed. In these cases, the alcohol reacts with a measured volume of either acetic or phthalic anhydride in pyridine solution. The loss in titratable acidity in the anhydride solution is a direct measure of the hydroxyl groups reacting in the sample. These procedures are generally free from interference by other functional groups, but both are affected adversely by the presence of excessive water, as this depletes the anhydride reagent strength to a level below that necessary to ensure complete reaction with the alcohol. Both procedures can be adapted to a semimicro- or even microscale deterrnination. 

Titrier-flasche,/. titration bottle (for feeding a buret), -fliissigkeit, /. titrating solution, standard solution, -gerate, n.pl. titrating apparatus, -methode, /. titration method, volumetric method, -saure, /. titrating acid, standard acid. 

The mixture is allowed to stand at room temperature overnight, the crystals filtered off and washed on a filter with acetone. The product Is obtained as colorless needles, which melt at 111° to 112.5°C. The methylsulfate is not stable indefinitely. For preparation of pure chloride salt it is desirable to use methylsulfate which gives no titratable acidity with sodium hydroxide using bromophenol blue as indicator. 

Mesoxalic dialdehyde can be reasonably expected (16,28,50) to undergo normal glycol cleavage and give one mole of formic acid and one mole of glyoxylic acid in fact, when a second molar equivalent of periodate was added to the above solution, two molar equivalents of titratable acid were formed. If an excess of periodate is now added, two molar equivalents of titratable acid remain, but in addition, one molar equivalent of carbon dioxide can be expelled from the solution. Thus, in the overall reaction, one mole of triose reductone is oxidized by three moles of periodate to give two moles of formic acid and one mole of carbon dioxide ... 

Fruit and vegetable juices packed with 21-26 in. of vacuum and stored in uncoated aluminum cans caused severe corrosion as shown in Table III. The corrosion rate brought about by the juices depends more on the nature of the organic acid present and the buffering capacity of the juice than on the total titratable acidity (11). The use of coated aluminum containers considerably minimized corrosion problems. Product control under extended storage conditions may be achieved by using specific chemical additives. However, more work is needed in this area before final conclusions can be reached. 

Acid value3 Phenolphthalein titration Acid-alkali neutralization... 

Acid value/H2S04a Potentiometric titration Acid amine neutralization in nonaqueous medium... 

Gur ev, I. A. Zinina, O. B., Improving conditions for titrating acids by using dual-phase systems, J. Anal. Chem. USSR 33, 1100-1102 (Engl.) (1978). 

When titrating acids with a strong base, the acids titrate in order of increasing pKa. A carboxylic acid titrates before a protonated amine when strong base is added. 

A possible reason for the inaccessibility of a part of the acid groups could be the crosslink density which depends on the composition of the microgels. However, because the number of titratable acid groups does not depend on the composition and, therefore, on the crosslink density of the microgels, it must be concluded that electrostatic forces prevent ions from entering the microgel particles. 

Fig. 32. Relation between the residual unsaturation ( ) IR-spectroscopy, (O) hydrolytic degradation resp. the titratable acid groups of microgels (a) and their EUP-content [132]. EUP(MA+HD),Mn 1640, c/t 67/33, EUP/S varied, W/M 20.

Recently a quantitative method for the determination of carbonyl groups in oxidized xylan has been developed.106 The method involves the reaction of the carbonyl group with O-methylhydroxylamine hydrochloride to form the corresponding oxime with the liberation of one mole of titratable acid. 

In the morning, after the subjects delivered the urine samples, pH, total titratable acidity (TTA), and their calcium and sulfate contents... 

The total titratable acidity (TTA) of the urine varied significantly between the two dietary periods, P<0.02. During the soy period, the TTA ranged from 10 to 50 mEq/d. Meat consumption was accompanied by an increase in the TTA values which ranged from 15 to 70 mEq/d, Figure 1. 

Compared with the TTA during the prediet period, the soy bean diet resulted in an increase by day 2, with the same value for TTA on day 5. Thereafter, there was a slight decrease on day 7. The TTA values for day 2 ranged from 12.7 to 44.6 mEq/d. Why there should be this 3.5-fold spread in the excretion of titratable acid for subjects consuming the same diet is unknown. 

Figure 1. Effect of soy bean and meat diets on average urinary total titratable acidity (TTA) and calcium. Upper two curves represent TTA lower two curves, urinary calcium. Bars indicate...

The similarity in sulfate excretion during the meat and soybean periods (Figure 2) indicates that the two diets were well matched for sulfur content. Despite this similarity, the titratable acidity of the urine during the soy bean period was far below that of the meat period and did not follow the sulfate excretion. This suggests that some other anion other than sulfate in the titratable acid may have decreased while sulfate rose, Figuies 1 and 2. 

The meat diet resulted in markedly greater titratable acid and calcium excretion compared with the soy diet (P<0.02). This occurred despite the fact that each diet contained the same amounts of protein, calcium, phosphorus, and sulfur. Increased urinary calcium excretion in subjects accompanied this increased output of TTA (P<0.02) ... 

Potentiometric titration is actually a form of the multiple known subtraction method. The main advantage of titration procedures, similar to multiple addition techniques in general, is the improved precision, especially at high determinand concentrations. ISEs are suitable for end-point indication in all combination titrations (acid-base, precipitation, complexometric), provided that either the titrand or the titrant is sensed by an ISE. If both the titrant and the titrand are electro-inactive, an electrometric indicator must be added (for example Fe ion can be titrated with EDTA using the fluoride ISE when a small amount of fluoride is added to the sample solution [126]). 

As the alkylation catalyst ages, its titratable acidity decreases because it becomes diluted with water from the feed stock and with water and complex hydrocarbon oils produced by side reactions. The catalyst is ordinarily discarded when its titratable acidity drops to 85 to 88%. If the catalyst is used further, the quality of the alkylate deteriorates rapidly, and the hydrocarbon-acid emulsion becomes so stable that separation difficulties are encountered in the acid settler. 

The catalyst acidity in the reactor can be maintained at any desired strength by regulation of the acid regeneration tower feed rate. For the production of aviation grade alkylate, the titratable acidity of the circulating acid is usually maintained in the range of 85 to 90% hydrofluoric acid. 

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