The Volumetric Determination of Tellurium by the Dichromate Method

Volumetric Determination of Tellurium in Organic Compounds

“…Lenher and Wakefield (9) claim the degree of acidity is important to this method, and 2% hydrochloric acid solution is desirable during the titration. The acidity provided by the digestion mixture appears to be quite satisfactory in the above method.…”

“…Volumetric methods using potassium dichromate (9,14), potassium permanganate (7), and ceric sulfate (IS) for the oxidation of tellurium from an oxidation state of IV to VI have been reported, as well as iodometric (4, B), instrumental (1,6), and gravimetric (9, 9, 10) methods employing elemental tellurium. Only the gravimetric methods by Drew (S) and by Tsao (IS) have been specifically developed for organotellurium compounds, although solution of the elemental tellurium and titration of the solution have been suggested by the work of others.…”

“…The sample is initially digested xvith concentrated nitric acid and then further decomposed xvith perchloric acid. After dilution, the sample is titrated xvith standard potassium dichromate solution according to the method of Lenher and Wakefield (9), using sodium diphenylamine sulfonate indicator (14)• 3TeOz + K2Cr20, + 8HC1 -> 3H2Te04 + 2KC1 + 2CrCl3 + H20 0 Low result due to the sample having been evaporated to dryness. 6 High result due to the sample not being digested to a water white solu-® = S/y/ n "Student" deviation S 1 part, are not too restrictive, and a number of samples may be analyzed rapidly and conveniently using no special equipment or chemicals.…”

Determination of Tellurium in Tellurium-Containing Organic Compounds by Microwave Plasma-Atomic Emission Spectrometry

“…The increased interest in this field is due to widely use of these substances as catalysts in organic reactions (e.g., rubber vulcanization), inhibitors of metal corrosion, insecticides, fungicides, components of special photographic materials, pharmaceuticals etc [1][2][3][4][5]. In view of great practical importance of these compounds for science and technology, a large number of analytical methods for the determination of tellurium in various objects were developed: gravimetric methods based on the precipitation of elemental tellurium by treating with inorganic and organic reducing agents, [6][7][8]; titrimetric methods based on redox reactions using iodide-anion, salts of iron(II), chromium(II) or titanium(III) as reducing agents, as well as potassium permanganate or dichromate as oxidizing agents for Te (IV), [9][10][11]; electrochemical methods, which allow one to determine the tellurium and selenium at simultaneous presence with a sensitivity being 10 -5 M, [12][13][14]; spectrophotometric methods based on the formation of complexes with sulfur-containing organic reagents (diethyldithiocarbamate, thiurea, and their derivatives, bismuthiol II, and so on [15,16] or on the formation of ion pairs of tellurium acido complexes with organic bases-pyrazolone derivatives and rhodamine dyes [17][18][19]. Three spectrophotometric methods were used to determine small tellurium content in the environment (water, plant material, soil), and thin telluride films [20].…”

Rapid Determination of Tellurium in Tellurium-Containing Organic Compounds by Microwave Plasma – Atomic Emission Spectrometry

“…In view of great practical importance of these compounds for science and technology, a large number of analytical methods for the determination of tellurium in various objects were developed: gravimetric methods based on the precipitation of elemental tellurium by treating with inorganic and organic reducing agents [6][7][8] ; titrimetric methods based on redox reactions using iodideanion, salts of iron(II), chromium(III) or titanium(III) as reducing agents, as well as potassium permanganate or dichromate as oxidizing agents for Te(IV) [9][10][11] ; electrochemical methods, which allow one to determine the tellurium and selenium at simultaneous presence with a sensitivity being 10 -5 M 12,13 ; spectrophotometric methods based on the formation of complexes with sulfur-containing organic reagents (diethyldithiocarbamate, thiurea and their derivatives, bismuthiol II, and so on) 14,15 or on the formation of ion pairs of tellurium acido complexes with organic bases-pyrazolone derivatives and rhodamine dyes 16,17 .…”