Marczenko Z, Lobiński R
Department of Analytical Chemistry, Technical University, Warsaw, Poland.
Talanta. 1988 Dec;35(12):1001-4. doi: 10.1016/0039-9140(88)80236-4.
The formation and extraction of the ion-associates of the vanadium(V)-3,5-dinitrocatechol (DNC) anionic chelate complex with various basic dyes have been studied and a new sensitive extraction-spectrophotometric method for the determination of vanadium based on the system V(V)-DNC-Brilliant Green has been developed. Beer's law is obeyed up to a vanadium concentration of 0.3 mug/ml and the molar absorptivity is 1.7 x 1O(5) l.mole(-1). cm(-1) at 630 nm. The molar ratios of the components and the form of the vanadium(V) cation in the extracted compound have been determined, and the formula [VO(OH)(DNC)(2-)(2)]BG(+) is proposed. Titanium, molybdenum, tungsten, EDTA and thiocyanate interfere seriously. The method becomes specific after a preliminary separation of vanadium by its extraction as the BPHA complex from H(2)SO(4)-HF medium, and is 40 times more sensitive than the spectrophotometric BPHA method. The proposed method has been applied to determination of traces of vanadium (about 10(-5)%) in alums.
研究了钒（V）-3,5-二硝基邻苯二酚（DNC）阴离子螯合物与各种碱性染料形成离子缔合物及其萃取情况，并基于V（V）-DNC-亮绿体系开发了一种测定钒的新型灵敏萃取分光光度法。在钒浓度达0.3μg/ml时符合比尔定律，在630nm处摩尔吸光系数为1.7×10⁵ l·mol⁻¹·cm⁻¹。已确定了萃取化合物中各组分的摩尔比及钒（V）阳离子的形式，并提出了化学式[VO(OH)(DNC)(2⁻)₂][BG⁺]₂。钛、钼、钨、EDTA和硫氰酸盐有严重干扰。通过从H₂SO₄-HF介质中萃取钒形成BPHA络合物进行初步分离后，该方法具有特异性，且比分光光度法BPHA法灵敏40倍。所提出的方法已应用于测定明矾中痕量钒（约10⁻⁵%）。
