Spectrophotometric determination of tellurium in trace quantities by use of an ion-association complex.
The formation of an ion-association complex by the interaction of iodotellurate(IV) with cetyltrimethylammonium bromide is used as the basis of an extractive procedure to determine tellurium in the range 2.5-12.5 mug in a final aqueous phase volume of 20 ml. The method is simple, reliable and sensitive. Selectivity is achieved by separation of tellurium on aluminium hydroxide as collector.
Chemical Amplification Method by Spectrophotometry for the Determination of Trace Amounts of Selenium
A rapid and sensitive spectrophotometric method has been developed based on the extraction of the ion-association complex formed between ICl2− and Rhodamine 6G+ into benzene. The ICI2− is formed through iodine which is liberated during the oxidation of iodide by the selenium(IV) present in sulfuric acid medium. The method is sensitive and down to 0.1 μg selenium could be determined in an aqueous phase volume of 10 ml. The extracted Rhodamine 6G+–ICl2− complex has a molar absorptivity of 4.8 × 105 dm3 mol−1 cm−1 at 535 nm. Beer’s law is obeyed over the range 0.1 to 0.9 μg of selenium. The relative standard deviation is 2.4%. The method is made more sensitive and selective by adopting the aluminium hydroxide collection procedure. The interference of few ions such as Fe3+, VO3−, TeO32− and Sb5+ which were collected along with selenium on aluminium hydroxide, were overcome by adding proper masking agents. The method was applied to the determination of selenium in environmental ash sample, copper ore, bark sam...
Rapid colorimetric determination of tellurium with diethyldithiocarbamate in acetone-water medium
アセトン-水単一相中でのテルル-ジエチルジチオカルバミン酸錯塩の呈色を利用するテルルの迅速光度定量法について検討した.この錯塩はアセトン60%(v/v)溶液中で424mμ付近に吸収極大を示し,pH6.3～9.0の間では一定の吸光度を示した.呈色は光に対して不安定であるが,着色ガラス器を使用し,紫外線をさけて呈色後ただちに測定することにより,簡便にしかも再現性よくテルルを定量することができる.1～20ppmのテルル量について,420mμのフィルターを用いて吸光度を測定して得られた検量線は良好な直線性を示した.この波長での分子吸光係数は約3,200であり,感度は0.04γTe/cm2である.本法では鉄(III),銅(II)およびビスマスの存在は妨害となる.しかし,EDTAが共存するとき,8PPmのテルルに対して40PPmのコバルト,水銀(II),ニッケル,タングステン(VI),200PPmのアルミニウム,バリウムおよび400～1200PPmのヒ素(III),カルシウム,カドミウム,マグネシウム,マンガン(II),モリブデン(VI),鉛,セレン(IV),亜鉛の共存は影響がなかった.