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贵金属已知的显色反应中,除萃取浮选的以外,摩尔吸光系数(ε)达到或超过2×10~5I·mol~(-1)·cm~(-1)者为数甚少。就金来说,目前以乙基硫代米嗤酮的灵敏度最高(ε=1.95×10~5l·mol~(-1)·cm~(-1)),甲基硫代米嗤酮次之(ε=1.6×10~5l·mol~(-1)·cm~(-1))。碱性染料如罗丹明B与AuCl_4~-缔合萃取显色反应ε=9.7×10~4l·mol~(-1)·cm~(-1)。有关金(Ⅲ)-碘化钾-碱性染料体系显色反应仍未见报道。我们发现在明胶、TritonX-100和抗坏血酸存在下Au(Ⅲ)与KI、罗丹明B特别是丁基罗丹明B的显色反应具有很高的灵敏度,有色络合物的摩尔吸光系数分别为2.3×10~5l.mol~(-1)·cm~(-1)(罗丹明B)和1.2×10~6l·mol~(-1)·cm~(-1)(丁基罗丹明B),特别是后者,ε值之高实属罕见,故我们称之为超高灵敏显色反应。
In the known color reaction of precious metals, except for the extraction flotation, the molar extinction coefficient (ε) reaches or exceeds 2 × 10 ~ 5I · mol -1 cm -1. In the case of gold, the sensitivity of ethylthiomolysed ketone is the highest at present (ε = 1.95 × 10 -5 l · mol -1 cm -1) (ε = 1.6 × 10 ~ 5l · mol -1 cm -1). The basic chromogenic reaction such as rhodamine B and AuCl_4 ~ + was characterized by color reaction ε = 9.7 × 10 ~ 4l · mol ~ (-1) · cm ~ (-1). There is no report about the color reaction of gold (Ⅲ) -potassium iodide-basic dye system. We found that the color reaction of Au (Ⅲ) with KI, rhodamine B, especially butyl rhodamine B in the presence of gelatin, TritonX-100 and ascorbic acid has high sensitivity. The molar absorptivities of the colored complexes are 2.3 × 10 ~ 5l.mol -1 cm -1 and Rhodamine B 1.2 × 10 ~ 6l · mol -1 · cm -1 (butyl rhodamine B) , Especially the latter, the high ε value is rare, so we call it ultra-sensitive color reaction.