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钒的光度测定方法颇多。目前用于矿石及冶炼试样中微量钒的测定有 PAR 法、磷钨钒酸比色法和钽试剂法等。但对含有大量铝、镁、钙的试样需预先分离。本试验提出在 pH0.8～1.2盐酸介质中,利用1-(2-吡啶偶氮)-2-萘酚(PAN)与钒(Ⅴ)和过氧化氢生成三元络合物的颜色反应,以光度法测定铝土矿和电解质(渣)中痕量钒。Ⅴ(Ⅴ)-PAN-H_2O_2三元络合物组成为1:1:1,摩尔吸光系数ε_(580)=1.50×10~4,最大吸收峰为580纳米,在水溶液中 V_2O_5浓度从0.2～1微克/毫升符合比耳定律。在测定条件下,大量钙、镁、铝、锰、硅、钾、钠不干扰测定,钛、铁、铜、镓干扰测定,但当有柠檬酸铵和氟化铵存在时可掩蔽4毫克铁(Ⅲ)和1毫克钛(Ⅳ),因样品中镓和铜的含量较少故勿需分离。经试验回收率为96～105%,相对标准偏差为2.0%。以本法分析了全国十个不同地区铝土矿样和两个标样中的五氧化二钒。测得值与钽试剂法的测定值相吻合。本法不需复杂的化学分离,具有简便、快速,选择性和稳定性好等优
Vanadium photometric method quite a lot. Currently used for the determination of trace amounts of vanadium in ore and smelting samples are PAR method, phosphovanadotungstic acid colorimetric method and tantalum reagent method. However, the sample containing a large amount of aluminum, magnesium and calcium needs to be separated in advance. In this paper, the color reaction of ternary complex formed by 1- (2-pyridylazo) -2-naphthol (PAN) with vanadium (Ⅴ) and hydrogen peroxide in hydrochloric acid medium of pH 0.8 ~ Spectrophotometric Determination of Trace Vanadium in Bauxite and Electrolytes (Slag). The composition of Ⅴ (Ⅴ) -PAN-H_2O_2 ternary complex is 1: 1: 1, the molar extinction coefficient ε_ (580) = 1.50 × 10 ~ 4 and the maximum absorption peak is 580 nm. The concentration of V_2O_5 in aqueous solution ranges from 0.2 ~ 1 μg / ml is Beer’s Law. Under the conditions of the assay, a large amount of calcium, magnesium, aluminum, manganese, silicon, potassium and sodium do not interfere with the determination of titanium, iron, copper and gallium interfere with the determination, but in the presence of ammonium citrate and ammonium fluoride can mask 4 mg of iron (Ⅲ) and 1 mg of titanium (Ⅳ), so there is no need to separate because of the small content of gallium and copper in the sample. The test recovery was 96 ~ 105%, the relative standard deviation of 2.0%. This law analyzes bauxite samples from ten different regions of the country and vanadium pentoxide from two standards. The measured value is consistent with the tantalum reagent method. This method does not require complex chemical separation, with simple, fast, good selectivity and stability