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本文拟定了用溶剂浮选吸光光度法测定水相中痕量 NO_2~-离子的方案.以正戊醇为有机溶剂,CPB(溴化十六烷基吡啶)为捕收剂,浮选 NO_2~-与对氨基苯磺酸及α-萘胺所形成的偶氨染料,在534mm 波长处以试剂空白为参比测定吸光度,其表现摩尔吸光系数为6.6×10~6Lmol~(-1)cm~(-1),检测下限为0.3ppb.用于实际样品中痕量 NO_2~-离子的测定,五次测定的相对标准偏差为1.6％.1000倍于 NO_2~-离子的 Fe(Ⅲ)、Al(Ⅲ)、Cu(Ⅲ),Pb(Ⅱ)、Zn(Ⅱ)、Mg(Ⅱ)、Ca(Ⅱ)、SO_4~(2-)、NO_3~-、Cl~-、Br~-、PO_4~(3-)等共存物不干扰测定.
In this paper, a scheme of solvent flotation spectrophotometry for the determination of trace amount of NO_2 ~ - ions in aqueous solution was developed.Using n-amyl alcohol as organic solvent and CPB (cetyl pyridinium bromide) as collector, - with ammonia sulfonamide and α-naphthylamine formed by the ammonia dye, at a wavelength of 534mm reagent blank as a reference to determine the absorbance, which showed a molar absorptivity of 6.6 × 10 ~ 6Lmol ~ (-1) cm ~ ( -1), and the detection limit is 0.3ppb. The relative standard deviation of the determination of trace amount of NO_2 ~ - ions in real samples was 1.6% .1000 times that of NO_2 ~ - ions, (Ⅱ), Mg (Ⅱ), Ca (Ⅱ), SO 4 2-, NO 3 -, Cl ~ -, Br ~ -, PO 4 ~ 3-) and other co-deposit does not interfere with the determination.