Titrimetric determination of certain mercaptans with mercuric chloride

A procedure is described for the semimicro determination of certain mercaptans, by means of their reaction with mercuric chloride. The acid liberated during the reaction is titrated with standard alkali after addition of sufficient potassium iodide to convert the surplus mercuric chloride into a stable soluble complex. The procedure has been applied to determine 0.12-1 mmole of these compounds; the results are accurate to within 0.5%.     

Titrimetric determination of thallium

Summary Titrimetric determination of thallium(I) is carried out by treating the sulfate with reducing sugars in alkaline medium either at room temperature or by boiling. The metal obtained is oxidised with an excess of ferric ammonium sulphate at room temperature. The ferrous ion formed, corresponding to the thallium metal oxidised, is titrated against a standard solution of ceric sulphate using N-phenyl anthranilic acid as indicator. Metallic thallium has been observed to exist in three varieties under different conditions. The presence of potassium chloride protects the metal from aerial effects. Li⁺, Ca²⁺, Sr²⁺, Ba²⁺, Mg²⁺, Cd²⁺, Zn²⁺, Be²⁺, Ni²⁺, Co²⁺, Al³⁺, and Zr⁴⁺ interfere with the determining but Pb²⁺ and Th⁴⁺ do not.

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Zusammenfassung Zur maßanalytischen Bestimmung von Thallium(I) behandelt man zunächst dessen Sulfat in alkalischem Medium mit reduzierenden Zuckern bei Raumtemperatur oder im Sieden. Das dabei entstandene elementare Metall wird mit überschüssigem Eisen(III)-ammoniumsulfat bei Raumtemperatur oxydiert und die äquivalente Menge Eisen(II) mit einer Standardlösung von Cersulfat gegen N-Phenylanthranilsäure als Indikator titriert. Metallisches Thallium liegt je nach den vorliegenden Bedingungen in drei verschiedenen Formen vor und wird durch Kaliumchlorid gegen Lufteinwirkung geschützt. Li⁺, Ca²⁺, Sr²⁺, Ba²⁺, Mg²⁺, Cd²⁺, Zn²⁺, Be²⁺, Ni²⁺, Co²⁺, A1³⁺ und Zr⁴⁺ stören die Bestimmung im Gegensatz zu Pb²⁺ und Th⁴⁺.

     

Titrimetric determination of aminobenzoic acids

A novel titrimetric method for determination of aminobenzoic acids is based on their reaction with excess of bromine to form N-bromo-2,4,6-tribromoaniline, which liberates an equivalent amount of iodine when treated with iodide. The method is applicable to the aminobenzoic acids in the range 0.1-5.0 mg, with a recovery ranging from 96 to 99.7% and a coefficient of variation of 0.2-2.0%, depending on the concentration level.     

Titrimetric determination of phenol resorcinol and phloroglucinol

A new and sensitive titrimetric method with an amplification procedure has been worked out for the determination of 10-1000 mug of phenol, resorcinol or phloroglucinol. The method is based on reaction of the phenols with an excess of bromine to form bromosubstituted aryl hypobromites. After removal of excess of bromine with formic acid, the hypobromites are treated with iodide to liberate an equivalent amount of iodine, which is extracted into chloroform, then reduced to iodide and determined by the Leipert procedure with 6-fold amplification. The coefficient of variation does not exceed 0.4% for amounts of determinand > 100 mug, but increases to 1.5% at the 10-mug level.     

Titrimetric determination of chloramphenicol in pharmaceuticals

The simple titrimetric procedure to be described is based on acid hydrolysis of chloramphenicol and quantitative oxidation of the product by potassium dichromate in one step.     

Titrimetric determination of chloramphenicol in pharmaceuticals

The simple titrimetric procedure to be described is based on acid hydrolysis of chloramphenicol and quantitative oxidation of the product by potassium dichromate in one step.     

Titrimetric determination of aluminium in steel

A titrinetric method has been worked out for the determination of aluminium in plain steels using dicniorodiethyl ether to separate off the iron and titrating with hydrochloric acid first in the absence and then in the presence of fluoride.     

Titrimetric determination of mercaptans with chloramine-T

Propyl mercaptan, allyl mercaptan, 2-mercaptoethanol, cysteamine hydrochloride, thio-p-cresol, 2-aminobenzenethiol, 2-mercaptopropionic acid and thioglycollic acid react with chloramine-T in 2:1 molar ratio in the presence of iodide, forming the corresponding disulphides. Mercaptans having a free beta-carbonyl group do not react quantitatively. The oxidation of the mercaptans is a function of time, and the corresponding sulphonic acids are formed on allowing them to stand with excess of chloramine-T. The oxidation to sulphonic acid is, however, instantaneous in the presence of iodine cyanide which acts as a catalyst and preoxidizer. This method is simple, accurate and rapid, and as little as 0.5 mg of the mercaptan can be determined with +/- 0.25% error.     

Titrimetric determination of hydrazines with sulfatoceric acid

Titrimetric methods for the determination of hydrazine and some simple alkyl and aryl derivatives are described. Iodine monochloride serves as pre-oxidant and indicator, and sulfatoceric acid as the titrant. Mercury(II) is added to ensure complete oxidation of some compounds.     

Titrimetric determination of sulfate in mineral waters

The interaction of [PdCl₄]^2-_aqwith ethylene-bis(thioglycolic) acid (EBTGA) and β-ethylthioethylene(thioglycolic) acid (β-ETETGA), has been interpreted and evaluated quantitatively. The successive constants of palladium(II) with EBTGA and/or β-ETETGA in acid medium have been determined spectrophotometrically.     

Titrimetric determination of selenium in anodic slimes

The determination of selenium in the presence of tellurium and copper has been studied, to allow analysis of anodic slimes from electrolytic copper refining. Three methods have been developed for the determination of selenium in these slimes. They are based on the extraction of selenium with sodium sulphite, reduction of selenite with sodium sulphite, and separation of selenium and tellurium by adjustment of pH. Selenium (10(-3)-10(-2)M) is determined in the presence of tellurium, copper, iron, silver and lead. The methods are fast and simple, do not need expensive reagents, and give satisfactory results.     

Titrimetric determination of aminobenzoic acids via lodination

A simple, rapid, and accurate titrimetric method for determination of 50–2000 μg of o-, m-, or p-aminobenzoic acid is developed. The method is based on iodination of these compounds. The resulting iodide, after removal of excess iodine, is oxidized with bromine to iodate which is determined by the Leipert amplification procedure. The recoveries range from 96.8–99.8% and the coefficients of variation do not exceed 0.9% for above 500 μg of aminobenzoic acid, but they increase to 1.5% at the 50 μg level.