钴Ⅱ-甲基百里香酚蓝络合剂-亚硝酸根络合吸附波的研究及应用  

Complex Adsorptive Wave of CoⅡ-Methyl Thymol Blue-NO_2^- and Its Application[HT][ST]

作　　者：杨丽珠[1] 陈大茴[1] 刘传银[2] 刘炜[2] 陆光汉[2] 

机构地区：[1]温州医学院药学院,温州325027 [2]华中师范大学化学学院,武汉430079

出　　处：《分析化学》2005年第5期675-679,共5页Chinese Journal of Analytical Chemistry

摘　　要：在pH8.5、0.04mol/LNH3·H2ONH4Cl缓冲溶液中,钴甲基百里香酚蓝络合剂(MTB)在NaNO2存在下,于-1.23V(vs.SCE)产生一尖锐、灵敏的二次导数极谱波,峰电流与钴(Ⅱ)浓度在5.0×10-8～2.0×10-6mol/L范围内呈线性关系;检出限为1.0×10-8mol/L。研究了该波的性质及电极反应机理,证明该波为络合吸附波。峰电流由中心离子钴(Ⅱ)还原产生。络合物在汞电极上的饱和吸附量为5.18×10-9mol/cm2,符合Frumkin等温式。测得吸附系数β=6.86×105,自由能ΔGθ=33.30kJ/mol;电子转移数n=2。不可逆吸附的转移系数α=0.58,反应速率常数ks=2.26/s。方法用于VB12和模拟样中痕量钴的测定,结果满意。In 0.04 mol/L NH_3·H_2O-NH_4Cl buffer solution, at pH 8.5, a sensitive second derivative polarographic wave of the complex of Co-methyl thymol blue (MTB) appears at -1.23 V(vs.SCE) in presence of NO -_2. The peak current is proportional to cobalt concentration in the range of 5.0×10 -8 ～2.0×10 -6 mol/L , the detection limit is 1.0×10 -8 mol/L. Several electrochemical methods have been used to study the properties of the polarographic wave and the mechanism of electrode. It is proved that the wave is a complex adsorptive one. The peak current is produced by the reduction of Co. The saturated adsorption amount of the complex at Hg electrode is 5.18×10 -9 mol/cm 2 and the adsorption obeys Frumkin adsorption isotherm. The adsorption coefficient (β) is 6.86×10 5 and ΔG θ is 33.30 kJ/mol. The number of electrons transferred (n) is 2 and the transfer coefficient (α) of the irreversible adsorptive system is 0.58 and the rate constant of apparent electrode reaction (k_s) is 2.26 s -1 . This method has been successfully applied for the determination of trace cobalt in vitamin B_ 12 and artificial samples.

关 键 词：钴 甲基百里香酚蓝络合剂 亚硝酸根 络合吸附波 微量元素 人体 吸附系数 心血管疾病 中药 

分 类 号：O657.1[理学—分析化学]