Sulfate gravimetric determination

The alkah metals are commonly separated from all other elements except chlorine before gravimetric determination. In the absence of other alkaUes, sodium maybe weighed as the chloride or converted to the sulfate and weighed. WeU-known gravimetric procedures employ precipitation as the uranyl acetate of sodium—2inc or sodium—magnesium. Quantitative determination of sodium without separation is frequently possible by emission or atomic-absorption spectrometric techniques. 

Brenner et al. [ 169] applied inductively coupled plasma atomic emission spectrometry to the determination of calcium (and sulfate) in brines. The principal advantage of the technique was that it avoided tedious matrix matching of calibration standards when sulfate was determined indirectly by flame techniques. It also avoided time-consuming sample handling when the samples were processed by the gravimetric method. The detection limit was 70 ig/l and a linear dynamic range of 1 g/1 was obtained for sulfate. 

Experiment 6 The Gravimetric Determination of Sulfate in a Commercial Unknown... 

The gravimetric determination of sulfate can be and is most often used to finish the Eschka and bomb washing methods. The most serious concern is that the barium sulfate precipitated may be extremely fine and difficult to filter. This can be overcome by adding the barium chloride (BaCE) rapidly to the hot solution and stirring the mixture vigorously to obtain a barium sulfate (BaS04) precipitate,... 

In the present work, twenty-seven of these oils were separately analyzed for sulfur content and sulfur isotope ratio (Parr Instrument Company bomb. Sulfate in washings from the bomb were precipitated with Ba2+. The BaSOA precipitate served for gravimetric determination of the S-content conversion to S02 for mass spectrometry (4). The 3AS/32S abundance ratios are presented in the usual 63AS notation. 

Thiopyrylium salts can find application in analytical chemistry. Thus, 2,4,6-triphenylthiopyrylium chloride can be used as a precipitant for the quantitative gravimetric determination of anions (CIO4", 103 , NOj , BF4 ) (87MI3). Thiopyrylium salts can be also used in the spectrophoto-metric determination of bismuth (75URP482648), tellurium (77URP-558856), palladium (77URP558865), and alkyl sulfates (91URP1675746). 

Chlorides were determined by potentiometric titrations performed on distilled water dilutions. Carbonates and bicarbonates were either determined by titration or by calculation from pH measurements. Sulfates were determined by the gravimetric method utilizing BaS04 precipitation. 

There are many sources of potential error in the gravimetric determination of sulfate as barium sulfate. The greatest source of error concerns the tendency of barium sulfate to carry down and retain the constituents of solvent and precipitant. The most significant source is caused by the adsorption of extraneous (mainly chloride) ions by barium sulfate. 

Sulfate can be determined by titrating with barium ion, to precipitate BaS04. As in the gravimetric determination of sulfate by precipitation of barium sulfate, this titration is subject to errors by coprecipitation. Cations such as K", Na", and NHU" " (especially the first) coprecipitate as sulfates ... 

If the glass contains lead and/or barium oxide, the glass should be treated with a mixture of hydrofluoric and sulfuric acids and the insoluble lead and barium sulfates filtered off before the titration. Lead may also be precipitated with hydrogen sulfide. Small amounts of aluminum and iron may be masked with triethanolamine. Greater amounts of aluminum and iron must be preseparated by precipitation as their hydrated oxides in the procedure for gravimetric determination of alumina. If the content of iron oxide, alumina, and titania is large, they can be separated using a 25% solution of urotropin. 

The identity of the brown catalytic component, XXI, was established by gravimetric determination of the sulfate formed from reaction with SO2, equation (116), a reaction characteristic of transition metal peroxo complexes. 

The phosphates and the NaOH produced by hydrolysis reactions were determined by titration with acid. The determination of phosphates was done gravimetrically as 2 2 7 Sulfates were determined gravimetrically as BaSO after removing the phosphates as iron phosphate. The composition of the solid phases was determined from the composition of the phase complex and that of the corresponding saturated solution. Corrections were made for water of evaporation. 

Sampling and analysis of alkyl sulfates is the subject of ASTM standard D1570 (7). It recommends determination of water by azeotropic distillation, pH on a 0.1% aqueous solution, alkalinity by sequential titration, ethanol-insolubles, unsulfated material by liquid-liquid extraction, combined alcohol by saponification and extraction, and ester SO3 by saponification and titration or gravimetric determination of sulfate. Methods for free chloride and sulfate are also specified. 

Although gravimetric methods have been used traditionally for the determination of large amounts of tellurium, more accurate and convenient volumetric methods are favored. The oxidation of teUurium(IV) by ceric sulfate in hot sulfuric acid solution in the presence of chromic ion as catalyst affords a convenient volumetric method for the determination of tellurium (32). Selenium(IV) does not interfere if the sulfuric acid is less than 2 N in concentration. Excess ceric sulfate is added, the excess being titrated with ferrous ammonium sulfate using o-phenanthroline ferrous—sulfate as indicator. The ceric sulfate method is best appHed in tellurium-rich materials such as refined tellurium or tellurium compounds. 

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