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本文研究了在聚乙烯醇存在下,钼(Ⅵ)与溴邻苯三酚红和碱性染料-乙基紫产生的协同显色反应。探讨了利用协同显色反应进行分光光度测定痕量钼的可能性。在乙酸介质中,钼(Ⅵ)与溴邻苯三酚红和乙基紫形成[EV]_3[MoO_2(BPR)]离子缔合型配合物,其吸收峰位于535nm,相应试剂(BPR+EV)的吸收峰则位于640nm。摩尔吸光系数e_(536)=1.70×10~5L·mol~(-1)·cm~(-1)。双峰双波长法可使灵敏度倍增。Δε_(535～640)=3.20×10~5L·mol~(-1)。钼含量为0～0.16~μg/mL时,吸光度遵守比尔定律。桑德尔灵敏度(S)为0.00057μg/cm~2。反应具有较高的选择性,除锗、钛、钨、钒有较严重干扰以外,其它常见金属离子不干扰钼的显色。根据配合物的组成,推测了它的可能结构。
In this paper, the synergistic color reaction of molybdenum (Ⅵ) with bromopyrogallol red and basic dye ethyl violet was investigated in the presence of polyvinyl alcohol. The possibility of spectrophotometric determination of trace molybdenum by synergistic color reaction was discussed. In acetic acid medium, molybdenum (VI) forms [EV] _3 [MoO_2 (BPR)] ion association complex with bromopyrogallol red and ethyl violet. The absorption peak is at 535 nm. The corresponding reagent (BPR + EV ) Of the absorption peak is located at 640nm. The molar extinction coefficient e_ (536) = 1.70 × 10 ~ 5L · mol ~ (-1) · cm ~ (-1). Double-peak double-wavelength method can double the sensitivity. Δε 535 ~ 640 = 3.20 × 10 ~ 5L · mol -1. Beer’s law is obeyed when the molybdenum content is 0 ~ 0.16 ~ μg / mL. Sander sensitivity (S) was 0.00057 μg / cm ~ 2. The reaction has high selectivity, in addition to germanium, titanium, tungsten, vanadium have more serious interference, other common metal ions do not interfere with the color of molybdenum. According to the composition of the complex, it is speculated that its possible structure.