在硫氰酸盐介质中用汞还原后用铁（III）测定钨。
Determination of tungsten with iron(III) after reduction with mercury in thiocyanate medium.
作者信息
Yatirajam V, Dhamija S
机构信息
Department of Chemistry, Kurukshetra University, Kurukshetra-132110, Haryana, India.
出版信息
Talanta. 1976 Jan;23(1):56-8. doi: 10.1016/0039-9140(76)80013-6.
Tungsten(V) is formed by shaking for 2 min sodium tungstate solution in 0.4 M potassium thiocyanate-4M hydrochloric acid medium, with mercury. It is titrated with standard iron(III) solution. The thiocyanate present stabilizes W(V) to aerial oxidation and also acts as indicator. The W(V) can also be titrated potentiometrically in 7M hydrochloric acid, a tungsten wire electrode being used. Fe, Ni, Cr, Zr, Bi, Sb, Ce, Al, Pb, Ca and U do not interfere. Cu, V and As can be tolerated up to 5 mg. Co, Mo, Re, Nb and Mn interfere, but not in the potentiometric determination. The method is direct, simple, rapid, accurate and reproducible.
在0.4M硫氰酸钾 - 4M盐酸介质中，将钨酸钠溶液与汞振荡2分钟可形成五价钨。用标准铁（III）溶液对其进行滴定。存在的硫氰酸盐可使五价钨稳定以防空气氧化，并且还用作指示剂。五价钨也可在7M盐酸中用钨丝电极进行电位滴定。铁、镍、铬、锆、铋、锑、铈、铝、铅、钙和铀不产生干扰。铜、钒和砷含量高达5毫克时可耐受。钴、钼、铼、铌和锰有干扰，但在电位测定中无干扰。该方法直接、简单、快速、准确且可重复。
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