Acid quantitation

Oxidation of a glycol can lead to a variety of products. Periodic acid quantitatively cleaves 1,2-glycols to aldehydes and is used as an analysis method for glycols (12,13). The oxidation of propylene glycol over Pd/C modified with Pb, Bi, or Te forms a mixture of lactic acid, hydroxyacetone, and pymvic acid (14). Air oxidation of propylene glycol using an electrolytic crystalline silver catalyst yields pymvic aldehyde. 

Procedure. Weigh an empty stoppered weighing bottle, add about 2 g of syrupy phosphoric(V) acid and re-weigh. Transfer the acid quantitatively to a 250 mL graduated flask, and then proceed as detailed for sulphuric acid, but using the phenolphthalein-1-naphtholphthalein mixed indicator. 

Weak acids are compounds that donate protons quantitatively to hydroxide ions but not to water. All acids are proton donors, but whereas a strong acid quantitatively donates protons to water, a weak acid does not. Aqueous solutions of weak acids contain small concentrations of hydronium ions, making the solutions acidic, but nearly all the weak acid molecules remain intact. Representative of strong acids, HCl generates H3 O and Cl" quantitatively when dissolved in water. Representative of weak acids, HF remains predominantly as HF molecules when dissolved in water. However, HF donates protons quantitatively to OH ions to give H2 O molecules and F ions, as shown in Figure 4-9. 

The name of a carboxylic acid always ends in -ic, and the name of the anion ends in -ate. Figure 17-9 shows three simple carboxylic acids formic acid ( K = 1.8 x 10 ), acetic acid ( K — 1.8 X 10 ), and benzoic acid ( Ta = 6.4 X 10 ). HCO2 is formate, CH3 CO2 is acetate, and Cg H5 CO2 is benzoate. Examples and treat benzoic acid quantitatively. 

The reference standards are used to quantitate the standards that are employed in the kits to generate the standard curves. The kit standards are recombinant single-stranded DNA molecules that are added to either negative serum or plasma at known concentrations. Because the standard curve is not constructed with reference standards, Chiron initially chose to use the term equivalent to describe the units of nucleic acid quantitation in clinical samples. An equivalent was defined as the amount of nucleic acid in a clinical sample that gave a signal equal to one molecule of the reference standard nucleic acid. The term copy rather than equivalent is used to describe the units of nucleic acid quantitation in the HIV-1 bDNA assay. The terms are now used interchangeably. 

Smith [117] discussed the determination of tin in water. In the determination of low concentrations of the order of 40 ng of trialkyltin chlorides in sea water it has been observed that these compounds are very volatile and are easily lost upon evaporation with acid. Quantitative recovery of tin is, however, obtained in the absence of chloride ion during evaporation with acid. Preliminary removal of chlorides from sea water by passage down a column of IRA 400 resin before digestion with acid completely overcame loss of tin on subsequent evaporation, with acid giving a tin recovery of 90%. 

Nucleic Acid Quantitation Using the Competitive Polymerase Chain Reaction... 

Nucleic acid quantitation using the competitive polymerase chain reaction... 

To demonstrate the applicability of this support in organic synthesis, the authors immobilized a (p-bromophenyl) acetic acid which was then transformed into the corresponding biaryl by means of the Suzuki cross-coupling reaction with p-methylphenylboronic acid. Quantitative NaOH cleavage of the ester linkage yielded the released biaryl, of which no purity was mentioned. 

Hexuronic acids are decarboxylated in the presence of refluxing, aqueous acid to form 5, reductic acid (2,3-dihydroxy-2-cyclopenten-l-one 47) and very small amounts of 48 (5-formyl-2-furoic acid). The yields of these products decrease when dilute acid solutions are used. Most of this work was performed with hydrochloric acid the use of phosphoric acid was not nearly so effective. For instance, D-galacturonic acid quantitatively lost CO2 within 4 h with 3.5 A/ HCl, whereas only 12 mole% of the CO2 was recovered after 4 h with 1.2 M H3PO4. The yields of CO2 from several hexuronic acids (including polygalacturonic acid) were comparatively determined. The acidic decarboxylation of hexuronic acids is bi-molecular and dependent on both the hexuronic acid and hydrochloric acid concentrations. Prior labeling work had established that C-6 of the hexuronic acid is the source of the CO2. 

In their second short communication (1979) 55b>, Marshall reported that the ( )[10.10] isomer 61b was immune to epoxidation with m-chloroperbenzoic acid (quantitatively recovered after 3 weeks), while the (Z)[10.10] isomer was completely converted to epoxide within 3 min reaction time under the same condition. 

Dietary purines are not an important source of uric acid. Quantitatively important amounts of purine are formed from amino acids, formate, and carbon dioxide in the body. Those purine ribonucleotides not incorporated into nucleic acids and derived from nucleic acid degradation are converted to xanthine or hypoxanthine and oxidized to uric acid (Figure 36-7). Allopurinol inhibits this last step, resulting in a fall in the plasma urate level and a decrease in the size of the urate pool. The more soluble xanthine and hypoxanthine are increased. 

Fatty acids can be determined easily by GC and HPLC. Hydrolysis of polysorbate 80 will release oleic acid. Thus, if a suitable hydrolysis procedure can be established to release oleic acid quantitatively, either a GC or an HPLC technique can be performed to determine the amount of polysorbate 80 in Nasonex. Approximately 9 g of Nasonex and an equivalent amount of polysorbate 80 standard were transferred into two separate flasks, followed by the addition of... 

Hypophosphorous acid in slightly alkaline solution reduces selenie acid quantitatively to the element, which can be separated, collected, dried and weighed. If the selenium is originally in a high stage of oxidation it should first be reduced by boiling with hydrochloric acid until no more chlorine is evolved.6... 

Tartaric Acid. Quantitative measures of total tartrate are useful in determining the amount of acid reduction required for high acid musts and in predicting the tartrate stability of finished wines. Three procedures may be used. Precipitation as calcium racemate is accurate (85), but the cost and unavailability of L-tartaric acid are prohibitive. Precipitation of tartaric acid as potassium bitartrate is the oldest procedure but is somewhat empirical because of the appreciable solubility of potassium bi-tartrate. Nevertheless, it is still an official AO AC method (3). The colorimetric metavanadate procedure is widely used (4, 6, 86, 87). Tanner and Sandoz (88) reported good correlation between their bitartrate procedure and Rebeleins rapid colorimetric method (87). Potentiometric titration in Me2CO after ion exchange was specific for tartaric acid (89). 

About half of the NPN of milk is accounted for by urea. Orotic acid is a particular hallmark of the milks of ruminants milks of other species contain little if any of it (Larson and Hegarty 1977). The free amino acids constituting the a-amino N fraction in Table 1.6 include those that are also found in proteins, as well as ornithine, citrulline, and cx-amino butyric acid. Quantitative analyses of the mixture of free amino acids have been published (Deutsch and Samuelsson 1958 Armstrong and Yates 1963 Rassin et al. 1978). 

Weigh out 6.81 g monobasic potassium phosphate and quantitatively transfer to a 1-liter beaker with water. Add additional water to 900 ml and stir. Adjust pH to 2.40 with concentrated phosphoric acid. Quantitatively transfer solution to a 1-liter volumetric flask and bring to volume with water. Filter through a 0.45- im filter. Store up to 1 month at room temperature (-23 °C). 

But die idea is clear The strength of an acid can be quantitated by knowing how well it transfers a proton to some standard base. Moreover die extent to which it transfers a proton to the standard base could be compared with die extent to which other acids transfer a proton to die same standard base. Thus, by using a single base, we could not only measure the strength of an acid but also compare acids quantitatively. 

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