Volumetric determination

Gravimetric and volumetric methods are practicable for the quantitative determination of the a-sulfo fatty acid esters. Using gravimetric methods the surfactant is precipitated with p-toluidine or barium chloride [105]. The volumetric determination method is two-phase titration. In this technique different titrants and indicators are used. For the analysis of a-sulfo fatty acid esters the quaternary ammonium surfactant hyamine 1622 (p,f-octylphenoxyethyldimethyl-ammonium chloride) is used as the titrant [106]. The indicator depends on the pH value of the titration solution. Titration with a phenol red indicator is carried out at a pH of 9, methylene blue is used in acid medium [106], and a mixed indicator of a cationic (dimidium bromide) and an anionic (disulfine blue VN150) dye can be used in an acid and basic medium [105]. 

Volumetric Determination op Iodine by the Method op Leipert and Munster1... 

The student should be able to carry out at once, at any time, the usual volumetric determinations. As a rule the readiness to carry out titrations in the organic laboratory is not so great as is urgently desirable. 

Thus, most calculations in volumetric determinations (titrimetry) are enormously facilitated by using titer values, which may be seen in the following chapters related to various categories of volumetric titrations. 

In general, titrations governed by precipitation reactions do not really constitute an appreciable number in volumetric determinations in comparison to either redox or acid-base reactions. The interaction between silver-nitrate and sodium chloride in solutions result into the precipitation of silver chloride as shown below ... 

Elliot, W. E. Volumetric determination of calcium in blood serum. J. Biol. 

The direct volumetric determination of divalent manganese with EDTA... 

Spiers, C. II. Note on the volumetric determination of magnesium sulphate... 

Oximes, hydroxamic acids and related species are often used as reagents in inorganic analytical chemistry for precipitation, gravimetric and volumetric determinations as well as for preconcentration, extraction, derivatizations and subsequent determination of analyte using instrumental techniques. A brief review of analytical chemistry in general and of these species in particular follows. 

This highly sensitive calorimeter needs to be connected to a sensitive volumetric system in order to determine accurately the amounts of gas or vapor adsorbed. A schematic representation of the whole assembly is shown in Figure 13.4 [147]. The volumetric determination of the adsorbed amount of gas is performed in a constant-volume vessel linked to a vacuum pump. The apparatus consists of two parts the measuring section equipped with a capacitance manometer, and the vessels section that includes the cells placed in the calorimeter (a sample cell in which the adsorbent solid is set, and an empty reference cell). 

In the direct calorimetric determination (-AH = f(njj), the amount adsorbed (nj is calculated either from the variations of the gas pressure in a known volume (volumetric determination) or from variations of the weight of the catalyst sample in a static or continuous-flow apparatus (gravimetric determination), or from variations of the intensity of a mass spectrometer signal [151]. 

Other reagents which may be applied to the volumetric determination of sulphuric acid and sulphates are barium chromate and benzidine. In the case of the former, the solution of sulphate is precipitated by a solution of barium chromate in hydrochloric acid on subsequent neutralisation of the filtrate, a quantity of chromic acid, equivalent to the barium sulphate which has been precipitated, remains in solution and may be estimated iodometrically.6 Benzidine, on the other hand, is an organic base which forms a very sparingly soluble sulphate the solution of mineral sulphate is treated with a solution of benzidine hydrochloride and the precipitated benzidine sulphate removed by filtration when subsequently suspended in pure water the benzidine sulphate undergoes hydrolysis to a sufficient extent to permit titration of the sulphuric acid with standard alkali.7 Lead nitrate may also be... 

An alternative principle for the volumetric determination is to apply an acidimetric process. The thiosulphate may be oxidised with hydrogen peroxide in the presence of a known quantity of an alkali in excess and the excess of alkali measured by titration with standard add,8 or the oxidation may be effected with hydrogen peroxide alone and the resulting acidity directly titrated with a standard alkali 9... 

Instead of making a direct volumetric determination of the hydrosulphite it is possible to modify the process by estimating volumetrically the product of a primary reaction. For example the hydrosulphite solution may be submitted to atmospheric oxidation and the resulting acidity determined with standard alkali,2 or a mercuric salt may be reduced, the mercury produced being estimated subsequently by the addition of standard iodine solution and titration of the excess of iodine one molecule of hydrosulphite is equivalent to an atom of mercury and therefore to two atoms of iodine.4 Similarly, instead of the gravimetric estimation of silver as described above, the latter may be redissolved in nitric acid and determined volumetrically.5... 

Noth. — Regarding the volumetric determination of barium carbonate, see Mohr s Lehrb. CUcm.-anul. Tit.riermeth., 7 ed., p. 133 (1896) Sutton, Volumet. Anal., 9 ed., p. 70 (1904). 

Volumetric Determinations can of course be made with other solutions than the potassium hydroxide and hydrochloric acid solutions generally selected, provided they be equivalent. In such substitution, however, due regard must be given to the suitableness of the indicator. 

Quadrivalent cerium salts may be volumetrically determined by arsenious acid in aqueous sulphuric acid solution using a manganese salt as catalyst, with potassium iodate present as a promoter.2 Excess of arsenious acid is used and back-titrated with permanganate. If nitric acid is present in place of sulphuric acid, an alkali chloride and a trace of iodine are used to promote the action of the manganese salt. Direct potentiometric titration with arsenious acid may also be employed. 

Volumetric Determination of Sugars with Fehling s Solution.1—... 

Two separate portions of 50 c.c. of the filtrate are placed in 100 c.c. flasks, one being made up to volume with distilled water and the other inverted in the ordinary way, neutralised and made up to volume both solutions are then polarised and the saccharose calculated by Clerget s formula. The results may be checked by volumetric determinations with Fehling s solution, the saccharose and the pre-existing reducing sugars being then calculated. 

Titrations of TC-HC1 in non-aqueous medium are known. TC-HC1 is dissolved in glacial acetic acid, 6% mercuric acetate solution added and then titrated potentiometrically with 0.1 N perchloric acid in dioxane (96, 97, 98). Indirect volumetric determination of TC-HC1 after formation of a tetracycline -thiocyano-chrom (III)-complex through oxidation with KMn04, KBrC>3 and KIO3 has also been reported (99). 

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