摘要
合成了新显色剂2(2咪唑偶氮)苯甲酸(简称IABA),分子式C10H8N4O2,分子量216.20,熔点213℃,各级酸离解常数pKa1为3.2,pKa2为9.8,研究了它的性质及其与钴显色反应的条件。在pH7的NH4Ac介质中,试剂与钴形成紫红色络合物,λmax为546nm,试剂的λmax为462nm,Δλ为84nm,Co2+与试剂络合比为1∶2,摩尔吸光系数1.61×104L·mol-1·cm-1,Co2+在0~0.8mg/L遵守比尔定律。所拟方法直接测定了工业废水及VB12中痕量钴,结果与原子吸收法相符,加标回收率为101.3%~102.2%,RSD(n=6)在2.0%~2.7%。
The synthesis of a new reagent 2 (2 imidazolylazo) benzoic acid (IABA) and the condition of color reaction with Co 2+ are reported in this paper. The results from UV spectrometric, IR spectroscopic and 1HNMR spectroscopic analysis show that its structure formula is COOH NN[LJ(H,S(1)W(3,4,5)] N NH [JJ3,LX,X,2;5,Z,1*3/7;1,Z] with molecular formula C 10 H 8N 4O 2, molecular weight 216.20, m.p. 213℃, dissociation constants pKa 1 3.2, pKa 2 9.8. It is a red brown crystalline powder and easy to be dissolved in polar solvent. The new reagent reacts with cobalt to form a stable red complex (1∶2) in pH 7.0 NH 4Ac buffer solution with λ max =546 nm. The apparent molar absorptivity is 1.61×10 4 L·mol -1 ·cm -1 . Beer's law is obeyed in the range of 0~0.8 mg/L for Co 2+ . The interferences from numerous cations and anions on the determination of Co 2+ were examined. The results show that the maximum tolerance for foreign irons on determination of 20 μg of Co are K +, Na +, NH + 4,Cl -, Br -, I -, SO 2- 4, NO - 3, PO 3- 4, CO 2- 3, Ca 2+ , Mg 2+ 10 mg; Sr 2+ , Ba 2+ 4 mg; Cr 3+ 2 mg; As(Ⅲ) 1 mg; Mn 2+ , Zn 2+ , Sb 3+ , Pb 2+ , Hg 2+ , Ag + 0.5 mg; UO 2+ 2 0.2 mg, Sn(Ⅳ), Ni 2+ 0.5 mg; Fe 3+ , Cu 2+ 1.5 mg; V(Ⅴ) 0.01 mg; Bi 3+ 0.3 mg; Cd 2+ 0.005 mg; NH 4F, thiourea 500 mg, citric acid 2 mg; tartaric acid 100 mg. The method has been applied to the direct determination of trace Co 2+ in VB 12 , waste water samples with satisfactory results. The recovery of standard addition is 101.3%~102.2% with precision of 2.0%~2.7% RSD( n =6).
出处
《岩矿测试》
CAS
CSCD
北大核心
1998年第4期271-274,共4页
Rock and Mineral Analysis
基金
浙江省自然科学基金
关键词
咪唑偶氮
苯甲酸
分光光度法
钴
显色剂
imidazolylazo) benzoic acid (IABA), synthesis, spectrophotometry, cobalt